1. Bases Conversion Factors:

Ref: ASTM D3180 / ISO 1170 - Conversion to different moisture basesa. Dry factor (converts AD to Dry) (100-ADM)/100    Dry = AD / ((100-ADM)/100)  b. AR factor (converts Dry to AR (100-TM)/100    AR = Dry x ((100-TM))/100)  c. DAF factor (converts Dry to DAF) (100-Dry Ash)/100      DAF = Dry / ((100-Dry Ash)/100)  

Where:TM is Total MoistureADM is Air Dried Moisture (Moisture in the Analysis Sample)AR is As Received BasisAD is As Determined (Air Dried) BasisDry is Dry BasisDAF is Dry Ash Free Basis

 2. Two Stage Total Moisture Formula (Refer to ASTM / ISO)

Two stage total moisture determination is used when the coal sample is too wet to divide or crush without the potential of loosing significate amounts of moisture amounts of moisture.

TMar, % = [RMad, % x (100 - FMad, %) / 100] + FMad %M = Total moisture; FM = Free Moisture; RM = Residual moisture

3. Calorific Value Conversion Factors:

MJ/kg = kcals/kg / 238.846MJ/kg = Btu/lb / 429.923kcal/kg = MJ/kg x 238.846kcal/kg = Btu/lb / 1.8Btu/lb = MJ/kg x 429.923Btu/lb = kcals x 1.8

4. CO2 Emission Factor:

t/CO2/TJ = As Received Carbon x 3.667 x [10,000/NCV(p)] in kJ/kg= As Received Carbon x 3.667 x [2388.46/NCV(p)] in kcal/kg

5. Fuel Ratio

= Fixed Carbon / Volatile Matter

6. Hydrogen in Coal: Refer to ASTM 3180 / ISO 1170

In-as-much as hydrogen values may be reported on the basis of containing or not containing the hydrogen in water (moisture)associated with the sample, alternative conversion procedures are defined below:

Use following conversions to report H including or excluding H in moisture:

Total Hydrogen as-determined (ad): includes H in the analysis moisture

  1. Hydrogen (excluding H in moisture)H(dry base) = [Total Hydrogen(ad)-(AMx0.1119)] x (100/(100-AM))

2. Hydrogen (including H in moisture)H(ar) = [Total Hydrogen(db) x ((100-TM)/100)]+(0.1119*TM)

3. ISO 1170 reports H air-dried basis excluding H in the as analysed moisture.H(air-dried) = Total Hydrogen(as-determined) - (Analysis Moisture x 0.1119)

Hydrogen and Oxygen Factors based on the atomic weight of H20Hydrogen = Moisture X 0.1119Oxygen    = Moisture X 0.8881

7. Net Calorific Value (NCV) Conversion Factors:

Ref: Net Calorific Value (ASTM D5865-03)

The heat produced by combustion of a substance at a constant pressure of 0.1 Mpa (1 Atm), with any water formed remaining as vapour.

ISO 1928-1995  at constant volumeQv, net,m,J/g =( Q gr,v,d - 206.0 [ wHd ] ) x (1-0.01xMT) - (23.05x MT)Qv, net,m,kcal/kg = ( Q gr,v,d - 49.20 [ wHd ] ) x (1-0.01xMT) - (5.51x MT)

ISO 1928-1995  at constant pressureQp, net,m,J/g = { Q gr,v,d - 212.2 [ wHd ] - 0.8 x [wOd + wNd] } x (1- 0.01MT) - 24.43 x MT

Qp, net,m,kcal/kg = { Q gr,v,d - 50.68 [ wHd ] - 0.191 x [wOd + wNd] } x (1- 0.01MT) - 5.84 x MT

[ wHd ] = H content of the sample less Hydrogen present in the moisturew(H)d = w(H) x 100/100-MTMT= Total Moisture

ASTM 5865/3180 at constant pressureQp(net)ar,J/g = Qvar(gross) - (215.5 x Har)Qp(net)ar,Btu/lb = Qvar(gross) - (92.67 x Har)Qp(net)ar,kcal/kg = Qvar(gross) - (51.47 x Har) Har = total hydrogen where hydrogen includes hydrogen in Sample MoistureHar = [(Had-0.1119xMad) x (100-Mar)/(100-Mad)] + 0.1119 x Mar

8. Seyler’s Formula:

Various parameters of Coal can be estimated from the Ultimate Analysis and Calorific Value determinations, using Seyler's formula, and other similar calculations (e.g. Dulong's formula).

Reference:* COAL -Typology -Physics -Chemistry -ConstitutionD.W. Van Krevelen (third edition 1993) Page 47VMdaf = 10.61Hdaf - 1.24Cdaf + 84.15Hdaf = 0.069 (Qdaf/100+VMdaf) - 2.86Cdaf = [0.59 (Q,daf/100 - 0.367VMdaf) + 43.4]

 ** ISO 1928-1995 Part E.3.3Estimate of the hydrogen content, calculated using Seyler's FormulawH = 0.07 x w(V) + 0.000165 x qv,gr,m - 0.0285 x [ 100 - MT - w(A)w(H) - is the H content of sample less H contained in moisture, as % massw(V) - is the VM content of sample with moisture content MT, as % massw(A) - is the ash content of sample with moisture content MT, as% massqv,gr,m - is the gross CV of sample with moisture content MT, in joules/g

  Note.1** Only valid when the calculated Hdb is greater than 3%Note.2* Only valid when the Odaf content is less than 15%Note.3 Can give erroneous results if coal shipments are a blend of low and high                     rank coals

9. Dulong's FormulaGCV(db) = 333xC(db) + 1442(H(db) - O(db) / 8) + 93xS(db)GCV is in (kJouls/kg dry basis). C, H, O, S as percent on a dry basis

A draft survey is a means of determining the weight of material loaded onto or discharged from a vessel. This measures the displacement in water prior and after loading or discharge. By recording the initial displacement of the vessel, prior to loading (or prior to discharge) and then after, the weight of the cargo can be determined.

Experienced and highly qualified SGS surveyors can produce accurate draft survey weights. During the draft readings, several other key factors are taken into account and measured before the weight of the cargo loaded or discharged can be determined. These include:

The density of sea or river water Changes in quantity of ballast between initial and final draft readings Changes in consumables on the vessel between initial and final draft readings (fuel oil,

potable water, etc.) Allowance for trim and deformation corrections (SGS uses data from the vessel’s draft

tables)

The accuracy of a weight determined by draft survey depends upon sea conditions at the time of loading or discharge (pitch and swell) and the weight of the cargo loaded when compared to the total capacity of the vessel.

SGS has trained draft surveyors who work to a defined draft survey protocol. Raw data are fed into a spreadsheet format, which then calculates the weight loaded or discharged. This result is reviewed before being released to you and the raw data is retained for further review.

Draft Survey: Procedures and Calculation

Aug 25

SurveyorsSurveyors draft survey, marine surveyor 79 Comments

Draft Surveyor; Reading the Draftmark

Finally, I have comfort time to complete this post after having busy with some surveys that I should fulfil. Any terms on this post should be referred to previous post Draft Survey: Terms of Conduct.

 

The Draft Survey procedures and calculation ascertained as the following series :

 

1. Reading the draftmark of the ship, which consist of six (6) points of draftmarks, i.e.; Fore, Midship, and After at both sides of the ship,

2. Sampling and testing the sea water or dock water density at the place where the vessel floats,

3. Determining of deductible weights by measuring and sounding of ballast tanks, fuel oil, fresh water that existing onboard at the time of survey,

4. Using Hydrostatic Table provided onboard to calculation.

Reading the Draftmark of the ship

Commonly, all ship are designed with draftmark for working with Draft Survey to determined their actual weight. The draftmark could be find at six (6) points on the below places:

Forward Port Side (FP), Forward Starboard Side (FS), Midship Port Side (MP), Midship Starboard Side (MS), Aftward Port Side (AP), Aftward Starboard Side (AS),

View the Draftmark:

Draftmark illustration

Use the small boat to go around the ship and get as near as possible to the draft mark for best viewing. The surveyor should be read all above marks clearly, because reading the draftmark is the first and most essential process. I am not saying that other processses is not essensial, but this process is hard to do and involves many rules of conduct to gain the correctness and accuracy of Draft Survey itself (I will post it later). The draftmark read is recorded on the surveyor notebook, do not try to remember it or write down in your palm hand. Its useless and un-professional.

Sampling and testing the sea water or dock water density

After reading the draftmark, directly engage with the sampling of sea water or river water around the ship’s dock.  Why? Because the ship draft will not be the same at different water densities (at the lower density means the ship more sink and at the higher density means the ship more float).  Where as the water density is subject to changes which follow with water tide that carrying different water salinity and temperature on to the ship dock. The sea water density is indeed at density 1.025 and the fresh water at density 1.000. To determine the density of water, we need the instrument named Hydrometer or Density Meter. Inserted the Hygrometer on to the water sample on the Sampling Can or Tube, then we could check the scale pointed on the surface of the sampling water. Records the water dock density as survey data.

Determining of deductible weights by measuring and sounding

Deductible Weight could measure by sounding  the tanks which used the Sounding Tape or gauging the tank level by visual inspection. Any deductible weight such as Ballast Water, Fresh Water, Fuel and Diesel Oil, and Bilges is notify to check. Records all in the survey book includes with the density for Ballast and Bilges, and for Oil complete it with density and temperature . The Fresh Water was at density 1.000.

View the Sounding Pipe:

Sounding Pipe

Using Hydrostatic Table provided onboard to begin calculation,

I think all necessary data was completed, so we could do calculation. The calculation is uses Displacement Table or usually called Hydrostatic Table. This table is included all data that we need to complete the calculation.

Raw Draft Calculation; Fore Mean or Fm = (FP+FS)/2, Mid Mean or Mm = (MP+MS)/2, and Fore Mean or Am = (AP+AS)/2. while Apparent Trim  or AT = Am – Fm. the Apparent Trim is the Trim that visually find.

Draftmark posision and correction to perpendicular. As the ship draftmark is not placed at the perpendicular, the Fore and After draft should be corrected with distance from the draftmark to perpendicular. The correction rules is: if the Trim by Stern, the Fore correction should be minus and After correction plus, and if the Trim by Head (stem), the Fore correction should be plus and After correction minus. The Midship correction is parallel with the fore correction with the same pattern. Some Hydrostatic table provided with these correction result. But if not the reference pattern is  for Fore Correction or Fc = (Fd x AT) : LBM and After Correction or Ac = (Ad x AT) / LBM. Where Fd = Fore distance to perpendicular, Ad = After distance to perpendicular, and LBM = Length Between Mark or Length between Fore and After draftmarks  or LBM = LBP – (Fd + Ad).

True Draft Calculation / Draft Corrected; Fore draft corrected or Fcd = Fm + Fc, Mid draft corrected or Mcd = Mm + Mc, and After draft corrected or Acd = Am + Ac.

True Trim or TT : Actual  Ship Trim after draft corrected or  TT = Acd – Fcd.

Fore and After Mean Draft or FAm = (Fcd + Acd)/2, Mean of Mean Draft or MM = (FAm + Mcd)/2, and Mean of Mean of Mean Draft  or MMM or Quarter Mean = (MM + Mcd)/2.

The above calculation is similar with : MMM = {(Fcd x 1) + (Acd x 1) + (Mcd x 6)}/8. Coresponding to the MMM or Quarter Mean result, the surveyor could check the value of

needed parameters on Hysdrostatic table like; Displacement, TPC, LCF, and MTC. Records them accurately.

Get the Displacement or Disp. First Trim Correction or FTc = (TT x LCF x TPC x 100) / LBP. Could be plus or minus

depend on LCF. Second Trim Correction STc = (TT x TT x MTC x 50) / LBP. The result always plus (+). Displacement corrected by Trim or DispT = D – (FTc + STc). Density Correction or Denc = DispT x {(Aden – 1.025) / 1.025}. where the Aden is

Actual Density that surveyor has taken sampling and testing previously. The density correction commonly in minus (-), due to the Actual Density is usually lower than 1.025 (fresh sea water). In case of at some port where the water salinity is high, the density correction could be plus (+).

And we have got the Displacement corrected by Density or DispDenc = DispT + Denc. (after corrected by density we will get the actual ship weight as per shown by Draft Survey)

Deductible Calculation. The same as draft, the deductible also need to corresponding to the table that named Tank Table / Tank Capacity Table. Refer to the sounding records that done before, the surveyor could be calculate the total deductbile existing onboard. Total Deductible or Deduct =  Ballast Water + Fresh Water + Bilges + Fuel Oil + Diesel Oil,  this total should be minus to the Displacement corected by Density.

The Net Displacement or NDisp = DispDenc – Deduct. The Net Displacement is the actual ship weight after minus with deductible weight. For

Unloading, to estimate the quantity of cargo onboard, the Net displacement should be minus with Light Ship and Constant.

I think difficult for the amateur writer like me to describe the complex narration of draft survey calculation, but to make it clear, the sample of Draft Survey Calculation will be post sooner or later.. :)

Draft Survey: Terms of Conduct Draft Survey: Specimen of Calculation

79 Comments (+add yours?)

1. SurveyorsFeb 17, 2011 @ 09:25:08

Hi Rahul,

Please make it specific, what is the formula you mean? what calculation do you wanna do?

Regards,Surveyors

2. SurveyorsFeb 16, 2011 @ 16:13:45

Dear Ferdhy,

First way:- You have to read 12 (twelve) times when the swell showing the high and the low levels.- From the above reading you have to eliminate 2 readings (1 of the highest level and 1 of the lowest level)- Take 10 readings which you have to then make an average by divided to 10.- The result gained is the best draft that near to the actual draft.

Second wayIt is recommended to use the Draft Measuring Equipment. A measuring device may to be use to improve the accuracy of draft measurement. Such device are based on the principle that the turbulence on the surface of the water does not extend down to any great depth. they use a long, flexible, open ended, weighted hose projecting downwards to below the turbulence.

Regards,Surveyors

3. Rahul RaiFeb 09, 2011 @ 22:58:48

what is the formula for cargo calculation

4. ferdhyJan 26, 2011 @ 20:47:24

Dear mr. surveyor

how to read actual draft mark at water swell condition,thanks

5. SurveyorsJan 22, 2011 @ 12:55:02

Dear Anatoly,

I have no formula that you meant.

The trim factor is made for trim correction at Forward, Mid, and Aft. These correction applied at the mean draft to obtain the corrected mean draft.

Regards,Surveyors

6. SurveyorsJan 22, 2011 @ 12:55:01

Dear Anatoly,

I have no formula that you meant.

The trim factor is made for trim correction at Forward, Mid, and Aft. These correction applied at the mean draft to obtain the corrected mean draft.

Regards,Surveyors

7. SurveyorsJan 22, 2011 @ 12:48:47

Captaouf,

Yes you could do it. The Draft Survey is possible for any conditions you meant.

Regards,Surveyors

8. SurveyorsJan 22, 2011 @ 12:46:25

Hi George,

Thanks for your questions. As long as I know, the ship tank table is made calibrate with the trim (apparent trim). So, we have to refer to these trim.In the other hand, if you find any information from the ship that the table is made refer to actual trim, you should use the actual one.

Please remind me if any issues regards this.

Regards,Surveyors

9. AnatolyJan 05, 2011 @ 21:43:00

Good Day,Sometimes there is no LCF mentioned in ship’s hydrostatic tables, but there are “trim factor fwd” and “trim factor aft”. There is a formula to get LCF using both trim factors and LBP. Mr. Surveyor, do you have the formula?

Thanks for help.Anatoly.

10. captaoufDec 15, 2010 @ 13:25:29

it possible the calculate the draft survey with negative trim or even keel

11. GeorgeDec 12, 2010 @ 23:20:17

Dear Surveyors!

Have one question.When we calculate the draft survey we use corrected trim (after correcting for distances of draft marks from perpendiculars) to enter the hydrostatic tables and ballast tables. So it used corrected trim to look at ballast tables with trim corrections.

However when everybody calculates the bunkers in fuel oil tanks or mdo tanks at time of bunker survey everybody use simply d.aft-d.frw so called apparent trim. I mean that all chief engineers and surveyors I have seen so far use apparent trim to enter the capacity tables with trim for bunker tanks.

Why it so and is it a correct way?Will be appreciated to hear any comments.

Bat rgdsGeorge

12. SurveyorsDec 08, 2010 @ 14:34:03

Dear Ipah,

Thanks for comment. You may check the following links :- http://www.riam.kyushu-u.ac.jp/ship/ittc/presentation/Proc-Propulsion.pdf- http://www.martv.com/TECHPAPERS/All%20Papers/NavalArch/AnalysisA.pdf

Hope the above can help you.

Regards,Surveyors

13. SurveyorsDec 08, 2010 @ 14:07:08

Dear Traore,

Ballast calculation is simple, you could obtain by the following steps:- sounding the tank,- taken the ballast water density,- check the cubic quantity on the ship ballast tank table,- and calculate the Metric Ton quantity.

For example :- Sounding of tank DBT 1 P : 5.35 M,- Ballast Water Density : 1.020,- Cubic quantity on table at 5.35 M = 368.120 Cubic Meters,- Metric Ton quantity = 368.120 x 1.020 = 375.482.

Best Regards,Surveyors

14. SurveyorsDec 08, 2010 @ 14:00:26

Dear Nitin,

You could refer to the Loading Manual Book that provided onboard the vessel.

Regards,Surveyors

15. CADET IPAH MIUKELOM BENDec 05, 2010 @ 17:21:45

dear captian, could you please send me the procedure and methods of surveying one unit of the propulsion plant of a ship. i am a cadet of maritime academy of Nigeria.

16. TRAORE ABOUBAKARNov 23, 2010 @ 22:56:54

thank you for draft survey explanation.can you explain us how to make calculation on ballast?best regards

17. Nitin PatelNov 22, 2010 @ 18:17:04

Dear Sir,For bulker vessels ,could you pls. indicate any thumb rule OREmpirical formulae,that based on draft,how can we ascertainthe cargo weight which can be loaded in the vessel.The range maybe taken from Cargo load of 7000 MT up to 15000 MT.

18. SurveyorsNov 05, 2010 @ 13:01:55

You are welcome Nguyenvanluu.

19. nguyenvanluuNov 04, 2010 @ 12:43:25

I see this brief very useful to me to figure out steps to calculate the draft survey.Thanks!

20. SurveyorsNov 02, 2010 @ 15:08:48

Dear Mcdudz,

The Draft Survey formula has considered to deflection correction, due to it was made up to the Quartermean (Mean of Mean of Mean – MMM), meanwhile the deflection correction is applied at the Mean Draft. The calculation result is the same for both methods.

Example (briefly, the calculation is directly to corrected draft):

Fcd = 2.232Acd = 2.851Mcd = 2.502FAm = 2.542

1. For Draft Survey Formula :- MM = (FAm + Mcd) / 2 = 2.522- MMM = (MM + Mcd) / 2 = 2.512 (use to check corresponding displacement at table)

2. For Deflection correction:- FAm = 2.542- Hogging = 2.502 – 2.542 = -0.040 (Deflection or D)- Equivalent Draft = FAm + 3/4 D = 2.542 + (3/4 x -0.040) = 2.542 + (-0.030) = 2.512

For any abbreviations, you could refer to my late posts. Please advice me whether any mistakes.

Regards,Surveyors

21. SurveyorsNov 02, 2010 @ 13:37:05

Dear Santoso,

Thanks, there no simple formula for Draft Survey. The Formula that I have inserted on my previous posts, as commonly use on the Ship’s Draft Survey.

Regards,Surveyors

22. SANTOSOOct 26, 2010 @ 09:02:09

Dear sir,

I have respect for you explain any proble darft survey.Can you give me a simple formula to calculate cargo on boat with draft survey?Thanks for your answer.

Regards.Practicips

23. mcdudzOct 12, 2010 @ 00:18:28

Good day, I have some queries also, pls advise if the deflection correction are still aplicable now a days? As I look some draft survey reports, programs, the deflection correction is not found or applied. As you know in big ship’s specially more than 80,000 dwt, the deflection correction is big. Pls advise also your calculation in deflection correction if you have.

24. SurveyorsOct 04, 2010 @ 11:47:12

Dear Khan,

You can drop your question, comment or feedback on this website, due to I am rarely check my mail. My mail address is faisal.yusuf(at)live.com.

Regards,Surveyors

25. KhanOct 02, 2010 @ 21:34:10

Dear Sir

What is your email address? I tried to post my questions 3 times but seem like it go no where. Thanks.

Regards

26. SurveyorsSep 10, 2010 @ 00:01:52

Hi Luis,

I have ever found the same case like yours. The best you can do is find the terms on Hydrostatic Table that you working with. Usually in the first page you will find it.

When the first time meeting with this case, I am very confusing. I try to guess the LCF, and reopen the Hydostactic Table many times but nil. Then.. I asked the Chief Officer about it. Unfortunately he did not know because he is the new Chief Officer and doing calculate with the Loading Manual on Ship’s Computer. Or he wanna test the surveyor at the time :)

In the end, I reopened the data page and rechecked the Terms :

LBP = Length between PerpendicularMTC = Moment to ChangeTrim at 1 cm.etc.. etc. then I foundLCA = LCF (Longitudinal Center of Floatation)That the answer.. So, I back to the table and checked the LCA and written down as LCF.In the case, you may also find LCB = LCF.

It is recommended for surveyor to check the terms and the calculation rules that provided on the Hydrostatic Table prior doing calculate. If you are in doubt, please asking for the Original Hydrostatic (in blue printing) from the ship to get the correct information and calculation.

Regards,Surveyors

27. Luis ZunigaAug 16, 2010 @ 02:29:53

Dear Sir.

In some vessels I have found that no information about LCF is vailable in the Hydrostatic tables, all the others are except LCF. Unfortunately no cross curves were available, no more ship’s info available also

There is some way to calculate the LCF value??

Appreciatte in advance your answer.

Luis

28. venu gopalJul 28, 2010 @ 19:38:31

Dear Surveyor can u pl mail me what is the procedure to calculate draft of Petroleum Tanker / vessel and oil tanker / vessel

29. surveyorsJul 07, 2010 @ 01:31:59

Hi Tamim,

Terimakasih untuk komentarnya..

Mungkin kamu belum begitu familiar dengan istilah perkapalan. Atau kalau bahasa yang menjadi kendala, kamu bisa kopi artikel nya dan terjemahkan di http://translate.google.com/#.

Ada juga Training Draft Survey yang diadakan oleh Asosiasi Independent Surveyor Indonesia (AISI) coba check di http://www.aisi-indonesia.org.

Salam,Surveyors

30. surveyorsJul 07, 2010 @ 01:19:29

Hi Feras,

Please clarify what does “the vessel is half loaded but yet above zero” means? So, I could try to find the answer. Thanks.

Best Regards,Surveyors

31. tamimJul 05, 2010 @ 15:11:13

dir pak surveyor,terima kasih atas artikel bapak ini, saya tertarik ingin mempelajari draught surveytapi, saya bingung untuk mempelajarinya, karena ada istilah yang tidak saya mengerti dan perhitungannyasaya harap bpk mw memberi penjelasan tentang draught survey, istilah yang sering d gunakan dan contoh perhitungannya

32. ferasJul 04, 2010 @ 08:54:26

dear sir,my question is: regarding the lcf sign as to be applied for the formula used to calculate the first trim correction. what sign does the LCF get if it is reducing.i.e the vessel is half loaded but yet above zero!? is it minus or plus???very urgent reply required

33. surveyorsMay 30, 2010 @ 14:24:21

Waalaikum Salam..

Me in my best, thanks.

Draft Mark reading is the essential part of Draft Survey, where the Draft Survey is begin from the reading part. There are some rules to get the best result. Actually it should be write down in one posting, but the basics are :- Read the Draft Marks as close as possible,- Use the small boat to read close the Draft Marks, do not see it from the ship’s maindeck,- Vessel is secured at the wharf properly,- No any ship’s gears movement allowed at the time, (such as crane, derrick etc),- No any ship’s liquids transfer activity allowed during reading, (ballast, fresh water, fuel and diesel oil),- Find the draft in meter first then continue with centimeter to prevent big error.- For the heavy swell sea condition it is recommended to read and record 12 times, taken out 1 biggest and 1 smallest of the reading results, and make avarage draft from the 10 results remained.

Trying to post this as complete version soon.

Second one, you could check my last post Draft Survey : Terms of Conduct for Light Ship and Constant Terms.

Regards,Surveyors

34. surveyorsMay 30, 2010 @ 13:57:54

Dear Joe,

Fisrt, the Density Correction is the correction for water mass weight. Commonly, the Ship Hydrostatic Table is makes at Sea Water Density (1.025). As the ship is floating on the sea water or river water that may have different densities, it shoud be applied density correction to gain the actual weight.

There is no relation between Density Correction to Ship Light Ship and Constant.

Regards,Surveyors

35. Joe TOVAMay 27, 2010 @ 11:39:47

Dir Sirs,

I’m new in this field of surveying and I was hoping if you could clarify the following;

Displ Corrected for trim – Actual Displ = Density correction.

Q: What’s the significance of ‘density correction’ and also is there a relation between Density Correction and the Ships lightship constant.Would greatly appreciate your expect advice and answers.

Kind RegardsJoe TOVA

36. Ejaz KhanMay 26, 2010 @ 13:19:56

AssalamoalykomDear Faiselhow r u, I read your data related to draft survey which is very helpful for me and i learn manay thinks which I not know abt. I am First time asking to you some questions my 1st question is that plz can you Expalan that which kind of Ruls are involved to Record Draft

Marks (You said abt that you will post later) and my 2nd question is What is light ship & Constent onboard. please if you can send me answer by mail i will very thankfull of you

Best Regard Ejaz Khan

37. johnMay 10, 2010 @ 22:40:09

Good day. I am a junior surveyor struggling to learn draft surveyI would like to know the formula to calculate especially

LBM: length between markFD “ Fore distance to perpendicular:AD : after distance to perpendicular:Thank you very much indeed

38. MannuMay 02, 2010 @ 19:55:40

Dear SirHow do i calculate approx. draft of a newly build vessel with all deadweight on board.What all parameters do i need for it from stability booklet.Can you explain with an example.

39. D.RATNAYAKEApr 02, 2010 @ 00:33:03

DEAR SIR,

HIGLY APPRECIATE IF YOU SEND ME BY RETURN MAIL THE ASTM TABLE 54 FOR VCF DENSITY& TEMP CORRECTION

TKS& RGDS

40. surveyorsMar 18, 2010 @ 10:08:51

Hi Mehdi,

Thanks for comment. Appreciated you as my Senior, as I have just completed 10% surveys of yours.

I think the data to be followed was written on the Hydrostatic Table. But if then we verify and will find that the both correction is applied trim to complete the calculation. The more trim you get the more correction will be.

FTc is more fluctuate than STc. Its happen due to point of LCF sometimes moving to the aft and fore of Ship Centre / Midship, where it will result the LCF in Minus and Plus. The value of LCF could be down below the 1.00 like 0.15 depends on the LCF’s distance from Midship. Mathematically, you have been times 0.15 with other numbers, but certainly you do devide it. This will be influent to reduce FTc total value when you do calculate it.

On the other hands, the MTC is not subject to minus. And the MTC value is typically the high number, means above 3.00, so it will advance for your calculation.

Anyone has any advice? waiting for your comment.

Regards,Faisal

41. surveyorsMar 18, 2010 @ 09:54:54

Nitin, when all the requirements in the calculation of survey based on the Draft UN / ECE Code 1990 followed, the accuracy could be expected in the limit:- For ship >10,000 DWT between 0.1 s / d 0.3%.- For ship <10,000 DWT between 0.3 s / d 0.6%.

In fact the practice of this ideal condition can rarely be achieved minimum range within the limits 0.5% of the total weight.When the technique is still less true implementation, the deviation can be achieved up to 1%.

Here the experience and skill of surveyor are involved.

Regards,Faisal

42. surveyorsMar 18, 2010 @ 09:13:50

Dear Nitin,

Thanks, the Specimen of Calculation on the post is made for initial survey, when the ship arrive at discharge port. In the next steps, the surveyor need to carry out the final draft survey in the same way when the ship has completed discharge her cargo.

The initial survey Net displacement that deducting / minus with the final survey Net Dispalcement will show you the total amount of cargo discharge from the mentioned ship.

Regards,Faisal

43. Nitin PatelMar 17, 2010 @ 19:10:00

Dear Sir,Could you throw some light on tolerance limits of Draft survey for differentvessel sizes.

44. Nitin PatelMar 17, 2010 @ 19:06:12

PLs. explain me the total draft survey of a dry bulk vessel with detailed calculations .Pls. use one illustrative example and make use of figures,

45. surveyorsMar 03, 2010 @ 14:03:49

Hi Nick,

Thanks, as known the correction is applied from the draft mark location. You could refer it to the Fore and Aft Distance on Hydrostatic Table that provided by the ship and compare with your draft reading place.

As my experience, the draft at the Aft on the flat of stern that usually found in the container ship is additional draft for reference only. You should check the port and starboard draft at stern for your draft survey.

Regards,Faisal

46. surveyorsMar 03, 2010 @ 13:40:23

Hi Herah..

Thanks for your questions.

Refer to your first question, I will post soon: how to calculate ship bunker.

The second: For SG 0.9900 is included on 0.8595 to 0.9245 with Correction Factor Per Degree Celcius at 0.00065.

Regards.Faisal

47. NickFeb 28, 2010 @ 18:24:26

Pls advise if the draft marks aft are on the flat of the stern and on the after end of the rudder need any correction or not. I see many containerships with the draft marks aft on the flat of the stern.

48. surveyorsFeb 26, 2010 @ 11:44:52

Hi Darussalam,

Thanks for your comment. Simplify the calculation for tank sounding were as follows :- Sounding resulting Quantity in Cubic Meter (see on Tank Quantity Table).- Quantity in Cubic Meter (x) Volume Correction Factor (from ASTM Table 54B) resulting Quantity in Kiloliter @15C.- Quantity in Kiloliter @15C (x) Weight Correction Factor (from ASTM Table 56) resulting Quantity in Metric Ton.- ASTM Table 54B for VCF is gained by Oils Density @15C and Temperature.- The complete calculation will be posting soon. Just check the blog later.

Regards..

49. student23Feb 25, 2010 @ 19:04:01

Sir,

what is the coefficient factor if you have 0.9900 Specific gravity @ 15 degree celcius?

50. student23Feb 25, 2010 @ 18:57:55

Sir, plz answer this problem for calculating bunker:

A vessel is to take a 1000 MT of IFO.Calculate correction made:SG at 15 degree celcius is 0.9900: TCF at 40 degree celcius is 0.9844:average combined SG+TCF is 0.9700.

Can you answer this problem ?

51. mehdi shamlouFeb 25, 2010 @ 17:16:36

Dear colleuges I have done almost 3000 attendances on vessels for draft survey..one thing which I still am thinking about and not found answer is in some cases the second trim correction was larger than FTC ..? Why

warm regradsmehdi

52. DarusFeb 25, 2010 @ 15:12:58

dear sir,thanks for the information… can you give me a simple calculation for tank sounding for bunker??Regards Darus,

53. surveyorsFeb 25, 2010 @ 13:21:15

Dear Ariz,

Thanks for comments. The above formula you have submitted is not correct. You’d better to check it, maybe you misplace the elements.

Regards,Faisal

54. Ariz DadizFeb 25, 2010 @ 02:20:49

Let ROB = x

A – B / C – B = x – D / E -D

(A-B/C-B)+D = x / (E-D)

(A-B/C-B)+D____________ = x(E-D)

55. Ariz DadizFeb 25, 2010 @ 01:11:33

is there any shortcut for the interpolation method shown above? I know my professor taught us but coudn’t remember.

thanksAris

56. surveyorsFeb 06, 2010 @ 11:49:28

Thanks Pandya,

You could check in my previous post and read the downloadable materials..

57. V.B.PANDYAFeb 05, 2010 @ 16:28:15

Hello, Sir,

I am also surveyor too, i want to know what is the MCTC and way they uses during draft calculation LCF and MCTC, kindly give me reply,

thanks,

58. surveyorsFeb 04, 2010 @ 13:55:27

Dear Ashveer,

Thanks for comment. Please take a look the sample of Interpolation on my post Draft Survey: Specimen of Calculation.I think there is no formula or easy method likes you meant. Because we should consider the unique shape of the ship to make calculation for Draft Survey (except for box shape vessel).

59. AshveerJan 23, 2010 @ 15:28:09

Good day. I am a junior surveyor struggling to learn interpolation . Is there a formula or do you have an easy method for calculating the weight using the true trim that is not on the hydrostatic table eg. T1 given t3 given calculate weight found t2 between given trims for a specific sounding. Really would appreciate your help

60. ToonaVaraRanoJan 02, 2010 @ 12:06:12

Thanks for the blogpost!

61. LaurDec 09, 2009 @ 14:54:30

I use this correction formula for ballast tanks:A=S-Trim*Ltank/(2*LBP)A – Adjusted Sounding at Aft Bulkhead TankS – Actual SoundingLtank – length of the tankTrim – vessel’s trim(+ to aft, – to fore)LBP – length between perpendicularsSo after getting A, refers it to the Tank Capacity Table to find the quantity on Tank.This formula can be used only when the tanks have a almost paralelipipedic shape (no way to be used for forepeak and afterpeak).If the vessel has no correction tables for ballast tanks is advisable to ask that the vessel to

be put on even keel(if is safe).Mr. “surveyors”Your formula show more ballast water in tank when vessel’s trim is to aft, which is not true.

62. studentOct 29, 2009 @ 17:51:20

Dear Sir,i was wondering if you could post any example of procedure in draft survey on calculating the ballast considering trim and when ballast in cargo hold corrections for add. height when measuring from top. Also procedure when calculating fuel.

Regards,student

63. surveyorsOct 28, 2009 @ 11:09:33

Thanks Suhendar,

The Draft Survey and Shore Scale / Weight Scale were the same function to determine quantity of cargo. as long as I known there is no rules to arrange the percentage of differences for both techniques. Caused each Technique should be accurate. Draft Survey is depends on the Hydrostatic Table calibration, and the Scale is depends on the accuracy of calibration of unit of Scale.

Both of them are recommended. And if the Techniques has the same accuracy, it should be resulted the same figure of weight quantity. For Bulk Cargo, it is recommended to use draft survey, because you never know how much cargo losses or spillages during discharging and conveying by truck to the Scale. The Scale is essensially uses for actual quantity received by the Receiver.

For other readers, please submit your comments if you have got the rules as Suhendar asked for.

Regards,Faisal

64. SuhendarOct 23, 2009 @ 11:14:46

Dear All,

Kindly pls advise the rule for percentage of different between draft survey with shore scale/weigher.

Thanks/Suhendar

65. surveyorsOct 14, 2009 @ 08:45:10

Alex,

You have to consider the trim of tug boat to obtain the correction of sounding that you have done, due to on tug / vessel with trim the liquid on tank were at different level between sides (fore and aft sides of tank). The correction is made to flat it on the same level (being actual liquid level) for calculation.

As your sounding quantity still in Cubic Meter, the density of fuel oil is needed to converted the Cubic Meter to Kilo Liter, and than from Kilo Liter to Metric Ton. ASTM Table 54b (for Volume Correction Factor or VCF) and Table 56 (for Weight Correction Factor or WCF).

Regards,Faisal

66. AlexOct 13, 2009 @ 20:02:43

Dear Sir,

What if we have to consider the trim of the tugboat and the density of the fuel oil?

Please advise.

Regards,Alex

67. AlexOct 13, 2009 @ 13:11:02

Thanks, that was really helpful.

68. surveyorsOct 08, 2009 @ 12:46:55

Dear Capt. Valter,

Thanks to comment.

Although in calculation the differences of both methods (1 and 2) in small quantities as well, but it could be a question to standard of draft survey that we have to use from the our customers.

I am in opinion that the Displacement corrected to density should be the displacement after corrected by the 1st and 2nd trim correction. By mean, the vessel displacement should be free from all vessels un-box shape and un-even keel correction before correcting by density. This method is commonly use for bulk carrier and it recorded on vessel hydrostatic table.

The UN ECE might be mean the same, the D they meant is D after 1st and 2nd trim correction, where we mentioned as DispT.

Waiting for your next comments. :)

Best Regards,Faisal

69. VALTER SUBANOct 07, 2009 @ 20:12:57

Dear sir,

I have find discrepancy between your way to calculate density correction and UN ECE recomandations (which is used as a standard for many customers). I’m asking You for the opinion becouse we have discousssed a lot among my coleagues.

The difference is in Displacement where by you Displacement corrected for the trim should be used, while by UN ECE standard the displacement from the table (line 161) should be used.

1. Your way and also my opinion is the same

Denc = DispT x {(Aden – 1.025) / 1.025}

2. UN ECE method

Denc = D x {(Aden – 1.025) / 1.025}

Please tell me your opinion.

Regards

Capt Valter Suban, M.Sc.

70. milindOct 03, 2009 @ 11:07:45

Thanks that was helpful.

71. surveyorsOct 03, 2009 @ 08:59:29

Hi Milind,

- Expect to read the Draft maximum sea vessels, although it is not possible or dangerous.- In circumstances like this, read the Draft and land next to the sea with the help of manometer, consisting of clear plastic hose, strong, mounted on both ends of the pipe to facilitate water level measurements.- If possible, pipes installed along the width of the entire ship – the size is taken from the overall width.- Reading Draft sea side obtained through adding to or subtracting from the land side of the manometer readings- The surface is measured from the same base line and taken to the same distance from both sides of the ship’s centerline.- All air must be expelled from the hose and the pipe surface is maintained at a higher elevation than the deck on the centerline.- The height of the water surface on both sides of the ship measured above deckline (h) or other fixed surface. The difference between the height divided by two and the result (d) is added to or subtracted from the readings Draft one to get the mean on Draft centerline.

SAMPLE OF CALCULATION- QUESTION:Draft midships left = 8.00M, the right side of the manometer readings 8.50M on both sides of centerline.Full width of the ship = 20.85m. Draft midships Calculate the mean, the centerline Draft, if the difference between the 2 readings manometer manometer readings higher right = 25cm.

- ANSWER: The width of effective 8:50 x 2 = 17.00M, with the triangle at 0:25: 17 = d: 20.85d = 20.85×0.25: 17 = 0.307m wide differences in management.Differences half-width = 0307: 2 = 0.153m. Centerline Draft = 0153 8:00 = 8.153m

DRAUGHT SURVEYTHE U.K. VERSION, 1994

72. surveyorsOct 03, 2009 @ 07:59:01

Hi Alex,

Thanks, you have to use interpolation to get the mentioned quantity.

Let’s assume 2.380 = A, 2.375 = B, 2.400 = C, 26.15 = D, and 26.50 = E.

The Formula is: ROB = D + {((A – B) / (C – B)) x (E – D)}

As per the above formula the ROB found 26.157 m3. You can try it. :)

73. Alex HoeSep 24, 2009 @ 00:26:02

Dear Sir,

I would like to know the formula to calculate the remaining bunker (MGO/Fresh Water/LO/GO/DO) on board based on the tank sounding table.

For example:Sounding – 2.38mTank sounding table shows:1) 2.375 – 26.15m32) 2.40 – 26.50m3How to get the value (ROB) at 2.38m?

Regards,Alex

74. MilindSep 23, 2009 @ 16:24:48

Can some one please guide me on the procedure of calculating overside drafts of a vessel with a list and where over side drafts cannot be successfully read.

75. surveyorsSep 08, 2009 @ 10:14:28

Hi Myo..

Thanks for your comments.

As I know, there is no differences for formula between the Ship and Hopper Barge Draft Survey. Draft Survey formula is for general uses.

For references, you could download the complete Draft Survey Standard and Procedures at this LINK

76. MyoSep 06, 2009 @ 16:09:51

Dear Sr,Your posted were support me to learn about Draft survey.I’m a junior surveyor in our country,Union of Myanmar at South East Asia.I want to request you that to explain about Draft survey for Barge carrier and Hopper calculation.Because the technique in our country were very poor to learn.I want to know the formula to calculate the water content of Sea Sand cargo.Regard,Myo

77. surveyorsSep 06, 2009 @ 12:31:14

Hi James, thanks for your question..

I have made try to adopt from Petroleum Calculation named Weight Formula. The formula is as follows:

A = S + {(U – DF) x F}Where :- A : Adjusted Sounding at Aft Bulkhead Tank- S : Actual Sounding- U : Sounding point distance to Aft Bulkhead- D : Total Height of Tank

- F : Trim Factor, where the formula is Trim divided by LBP.- DF = D x F.

So after getting A, refers it to the Tank Capacity Table to find the quantity on Tank.

For example No. 2 Water Ballast Tank Portside:Sounding = 1.27 meters,U = 3.00 meters,D = 19.00 meters,Trim = 2.50 meters,LBP = 182.00 meters

So we can calculate,F = 2.5 : 182 = 0.014 andDF = 19.00 x 0.014 = 0.261Then,A = 1.27 + {(2.5 – 0.261) x 0.014}A = 1.27 + (2.239 x 0.014)A = 1.27 + 0.031A = 1.301. (check on Tank Capacity Table).

Does anyone has the other correction ways? I would be plesant if you could submit reply to this comment.

78. James BarrSep 03, 2009 @ 05:37:39

I found your brief on draught surveys very informative. Can you advise if there is a standard correction formula for asertaining the amount of ballast in a tank where there are no trim corrections available.Regards,

James Barr

Draft Survey: Specimen of Calculation

Jan 26

SurveyorsSurveyors draft survey, marine survey, marine surveyor 47 Comments

As I have promised you, I write down this post to explain specimen of Calculation in Draft Survey. Please also refer to the previous post Draft Survey : Procedures and Calculation.

Ok, now we could directly go to the point. The vessel has alongside at the wharf in port to discharge the grain cargo. The Ship’s Particulars shown :

Name of Vessel : MV. OCEAN BALL, - Port of Registry (POR) : Panama, – Lenght Over All (LOA) : 182.00 M, – Lenght Between Perpendiculars (LBP) : 179.00 M, – Breath (B) : 32.20 M, – Depth (D) : 17.15 M, – Gross Tonnage (GT) : 28,342 MT, – Net Tonnage (NT) : 17,664 MT, – Summer Draft (SD) : 12.163 M, – Summer Deadweight (DWT) : 52,998 MT, – Light Ship (LS) : 7,780 MT, Constant (CS) : 320 MT, – Fore Distance to Perpendicular (Fd) : 1.70 M, – After Distance to Perpendicular (Ad) : 9.45 M.  See Picture :

Fore & Aft Distance

The Surveyor came onboard and made Draft Survey to determine the quantity of cargo on arrival. During inspection, she’s draft marks and others data finds as the followings :

- Fore Draft Port (FP) : 10.79 M / Fore Draft Starboard (FS) : 10.81 M.

- Mid Draft Port (MP) : 10.90 M / Mid Draft Starboard (MS) : 11.03 M.

- Aft Draft Port (AP) : 11.16 M / Aft Draft Starboard (AF) : 11.19 M.

- Density of Sea Water Sample (Den) : 1.021.

- Ballast Water (BW) : 265.00 Cubic Meter at Density 1.025, – Fresh Water (FW) : 183.00 MT.

- Fuel Oil (FO) :  612.00 MT, - Diesel Oil (DO) : 161.00 MT, – Lub Oil (LO) : 29.00 MT.

————————————————————————————————————–

The Draft Survey Calculation is described as below :

Raw Draft Calculation

- Fore Mean (Fm) = (FP + FS) / 2 = (10.79 + 10.81) / 2 = 21.60 / 2 = 10.800 M.

- Mid Mean (Mm) = (MP + MS) / 2 = (10.90 + 11.03) / 2 = 21.93 / 2 = 10.965 M.

- Aft Mean (Am) = (AP + AS) / 2 = (11.16 + 10.19) / 2 = 22.35 / 2 = 11.175 M.

- Apparent Trim (AT) = Am – Fm = 11.175 – 10.800 = 0.375 M.

- Length Between Mark (LBM) = LBP – (Fd + Ad) = 179.00 – (1.70 + 9.45)

= 167.85 M

Draft Correction to Distance to Perpendicular.

- Fore Correction (Fc) = (Fd x AT) / LBM = (1.70 x 0.375) / 167.85 = 0.003798

= 0.004 M (rounded to 3 Decimals).

- Mid Correction (Mc) = (Md x AT) / LBM = (0.00 x 0.375) / 167.85

= 0.000 M (Not Available)

- Aft Correction (Ac) = (Ad x AT) / LBM = (9.45 x 0.375) / 167.85 = 0.021112

= 0.021 M (rounded to 3 Decimals).

True Draft and True Trim

- Fore Draft Corrected (Fcd) = Fm + Fc = 10.800 + (-0.004) = 10.796 M.

- Mid Draft Corrected (Mcd) = Mm + Mc = 10.965 + 0.000 = 10.965 M.

- Aft Draft Corrected (Acd) = Am + Ac = 11.175 + 0.021 = 11.196 M.

- True Trim (TT) = Acm – Fcm = 11.196 – 10.796 = 0.400 M.

Final Draft Calculation

- Fore and Aft Mean (FAm) = (Fcd + Acd) / 2 = (10.796 + 11.196) / 2 = 21.992 /2 = 10.996 M.

- Mean of Mean Draft (MM) = (Mcd + FAm / 2) = (10.965 + 10.996) /2 = 21.961 / 2 = 10.9805 M.

- Quarter Mean (MMM) = (MM + Mcd) /2 = (10.9805 + 10.965) /2 = 21.9455 /2 = 10.97275 M

= 10.973 M.

- Or MMM = {(Fcd x 1) + (Acd x 1) + (Mcd x 6)} / 8 = {(10.796 x 1) + (11.196 x 1) + (10.996 x 6)} / 8

= (10.796 + 11.196 + 65.790) / 8 = 87.782 / 8 = 10.97275 M = 10.973 M.

————————————————————————————————————–

Hydrostatic Table

Refer to the Table, we could obtain :

Displacement (Disp)

- Disp  at 10.970 M :  54,266.860 MT (DISP. FULL).

- Disp at 10.980 M :  54,321.070 MT (DISP. FULL).

- Disp at 10.973 M : 54,266.860 +[ {(10.973 - 10.970) / (10.980 - 10.970)}

x (54,321.070 - 54,266.860)]

= 54,266.860 {(0.003 /0.010) x 54.210} = 54,266.86 + (0.3 x 54.210)

= 54,266.860 + 16.263 = 54,283.123 MT

Ton Per Centimeter (TPC)

- TPC  at 10.970 M :  54.210 MT (Below TPC on Table).

- TPC  at 10.980 M :  54.220 MT (Below TPC on Table).

- TPC at 10.973 M : 54.210 +[ {(10.973 - 10.970) / (10.980 - 10.970)}

x (54.220 - 54.210)]

= 54.210 {(0.003 /0.010) x 0.010} = 54.210 + (0.3 x 0.010)

= 54.210 + 0.003 = 54.213 MT.

Longitudinal Centre Flotation (LCF)

- LCF  at 10.970 M :  1.180 MT (Below LCF on Table).

- LCF  at 10.980 M :  1.190 MT (Below LCF on Table).

- LCF at 10.973 M : 1.180 +[ {(10.973 - 10.970) / (10.980 - 10.970)} x (1.190 - 1.180)]

= 1.180 {(0.003 /0.010) x 0.010} = 1.180 + (0.3 x 0.010) = 1.180 + 0.003 = 1.183 M.

————————————————————————————————————–

Moment To Change Trim (MTC)

- MTC = MTC 1 – MTC 2.

- MTC 1 = MMM + 0.5 = 10.973 + 0.5 = 11.473 M.

- MTC 1  at 11.470 M :  709.610  (Below Table).

- MTC 1 at 11.480 M :  710.060 (Below Table).

- MTC 1 at 11.473 M : 709.610 +[ {(11.473 - 11.470) / (11.480 - 11.470)} x (710.060 - 709.610)]

= 709.610 {(0.003 /0.010) x 0.450} = 709.610 + (0.3 x 0.450) = 709.610 + 0.135 = 709.745.

- MTC 2 = MMM - 0.5 = 10.973 - 0.5 = 10.473 M.

- MTC 2  at 10.470 M :  686.460  (Below MTC on Table).

- MTC 2 at 10.480 M :  686.770 (Below MTC on Table).

- MTC 2 at 10.473 M : 686.460 +[ {(10.473 - 10.470) / (10.480 - 10.470)}

x (686.770 - 686.460)]

= 686.460 {(0.003 /0.010) x 0.310} = 686.460 + (0.3 x 0.310) = 686.460 + 0.093 = 686.553.

So,  MTC = MTC 1 – MTC 2 = 709.745 – 686.553 = 23.192.

————————————————————————————————————–

**** From the above results, we collected the data as follows:

- Disp = 54,283.123 MT, - True Trim (TT) = 0.400 M, - LBP = 179.00 M,

- TPC = 54.213, – LCF = 1.183, - MCT = 23.192.

First Trim Correction (FTc)

- FTc = (TT x TPC x LCF x 100) / LBP =  (0.400 x 54.213 x 1.183 x 100) / 179.000

= 256.35916 / 179.00 = 14.331615 = 14.332 MT.

Second Trim Correction (STc)

- STc = (TT x TT x MTC x 50) / LBP = (0.400 x 0.400 x 23.192 x 50) / 179.000

= 185.536 / 179.00 = 1. 036514 = 1.037 MT.

Displacement Corrected to Trim (DispT)

- DispT = Disp + (FTc + STc) = 54,283.123 + (14.332 + 1.037) = 54,283.123 + 15.369

= 54,298.492 MT.

Density Correction (Denc)

- Actual Density (ADen) = Sample Sea Water Density = 1.021

- Denc = DispT x {(ADen – 1.025) / 1.025} = 54,298.492 x {(1.021 – 1.025) / 1.025}

= 54,298.492 x (-0.004 / 1.025)

= 54,298.492 x  (-0.0039024) = -211.896554 = -211.897 MT.

Displacement Corrected to Density (DispDenc)

- DispDenc = DispT + Denc = 54,298.492 + (-211.897) = 54,086.595 MT.

Deductible Weight (Deduct)

- BW = 265.00 x 1.025 = 271. 625 MT, – FW = 183.000 MT, – FO =  612.000 MT,

- DO = 161.000 MT, – LO = 29.000 MT.

- Total Deduct = 1,256.625 MT.

Displacement Minus to Deductible Weight = Net Displacement (NDisp)

- NDisp = DispDenc - Deduct = 54,086.595 – 1,256.625 = 52,829.970 MT.

Estimated Cargo onboard (EstCOB)

- To estimated quantity cargo onboard, we need to know about Light Ship and Constant. Light Ship and Constant data is provided on the Ship’s Loading Manual.

For the new ship, we could refer to the Constant on the Manual, but for the old ship it Constant may vary, please refer to the Chief Officer Constant Declaration or Draft Survey Previous Port, or we could calculate it in the final survey after the Ship completing to discharge her cargoes (empty Ship).

- Light Ship (LS) = 7,780.000 MT, – Constant (CS) = 320.000 MT.

- EstCOB = NDisp – (LS + CS) = 52,829.970 – (7,780.000 + 320.00)

= 52,829.970 – 7,100.000 = 44,729.970 MT.

————————————————————————————————————–

See the following Draft Survey Report Form..

http://sevensurveyor.com/wp-content/uploads/2010/01/draft-form.jpg

We have completed the Initial Draft Survey, I hope it useful and see you in the next post.

Surveyors.

Draft Survey: Procedures and Calculation Surveyors Moved

47 Comments (+add yours?)

1. SurveyorsFeb 17, 2011 @ 09:43:09

Dear George,

The actual constant will be getting when the ship is empty by Net Displacement – Lightship.Net displacement is the displacement after corrected by 1st and 2nd trim correction, density correction, and minus deductible (ballast, freshwater, bunker,etc).

Example : Net displacement 9,254 MT and lightship 8,888 MTCS = 9,254 – 8,888 = 366 MT

In the initial survey when the vessel carried 50,500 MT cargo (as per B/L), net displacement 59,754 MT and lightship 8,888 MT, you could calculate constant as well, but it is the proximate constant (as we do not know the cargo declare is right or not).CS = 59,754 – 50,500 – 8,888 = 366 MT.

Regards,Faisal

2. GeorgeFeb 14, 2011 @ 18:02:54

Mr.Surveyor could you explain haw to found CONSTANT (CS).and I understood, that it should be found before loading, and till to discharging cargo, it not changeable.Pleas, I’ll be very pricier.

3. SurveyorsJan 22, 2011 @ 13:36:44

Dear Nicolas,

I think is nothing wrong with your device, except the tiny one. My device was in the same range but it look bigger. It is Germany made and the temperature 27.5 C.

For temperature 20 C, it is industrial standard. Please check this link: http://pcdmiswiki.org/images/7/7f/NIST_History_of_Thermal_Compensation.pdf.

Regards,Surveyors

4. nicolasJan 17, 2011 @ 16:53:09

I ve just got a hydrometer ranging 1.0-1.1, but what confuses me is very small and ranging temperature is 20C.

5. captaoufDec 15, 2010 @ 13:20:28

it s possible the calculate draftsurvey with negative trim

6. SurveyorsDec 12, 2010 @ 22:59:49

Dear Benny,

Wellcome..

Regards,Surveyors

7. bennyDec 11, 2010 @ 07:39:53

Thank you so much for this column!….It is highly appreciated, please oh please never stop this …you information is vital to the assistance of junior surveyours like my self …i look forward to more information about surveying ….it’s such a bonus to my training …thanks again!!!

8. SurveyorsDec 08, 2010 @ 14:22:32

Dear Capt,

Up to now, I can’t found another method for 2nd trim corrections as you are requested.

Regards,Surveyors

9. SurveyorsDec 08, 2010 @ 13:51:09

Dear Budi Santoso,

The Trim is the different between the mean of After Draft and Fore Draft.

The calculation applied as follows :

Fore Draft Port side : 2.10 MFore Draft Starboard side : 2.12 MMean of Fore Draft : 2.11 M

After Draft Port side : 4.34 MAfter Draft Starboard side : 2.36 MMean of After Draft : 4.35 M

So, the Trim = Mean of After Draft – Mean of Fore Draft = 4.35 M – 2.11 M = 2.24 M.

Best Regards,Surveyors

10. captaoufDec 01, 2010 @ 01:03:16

dear sirs: i forget how i can foun 2em trim correction there 2 methode what is the second methode for 2 trim correctionbest regards

11. busanNov 15, 2010 @ 16:35:20

I am junior surveyor struggling to learn draft survey . could u explain ”the trim calculation”.thank’s

12. AshishNov 12, 2010 @ 14:59:01

Thanks

13. SurveyorsOct 20, 2010 @ 13:54:03

Hi Elattar,

Thanks for appreciation.

Regards,Surveyors

14. E.ElattarOct 11, 2010 @ 04:11:56

Dear Surveyor,

Thank you very much for the explanation.

It was brilliant and proves that you have incredible experience

15. samSep 23, 2010 @ 08:42:12

Bro can u explain to me with chart how to get the formula 4 the pependicular correction and trim correction.

16. MehmetSep 20, 2010 @ 16:08:49

hello,mean draft = 1.78 metersTPC = 10.52 mthow do we calculate her draft (in salt water) when she is loaded with 3000 mt of cargo please ?

thank you.

17. SurveyorsSep 10, 2010 @ 01:12:54

Hi Vishal,

Thanks, I will consider it. As now, my job volume is above normal, so I almost have no time to update this blog.

Best Regards,Surveyors

18. VishalAug 11, 2010 @ 21:31:19

Hi, I was going through the draft survey calucation sheet posted by you and it seems to be helpful for bingners… i would appreciate if you can post some litrature on trimming of bulk carriers too… thanks n good day

19. SurveyorsJul 30, 2010 @ 02:18:28

Dear Tun,

First, you could do separate the calculation (interpolation) to find the quantity at the trim and sounding easier. See the following steps how to find 2.46 at trim 3.578:

i. (3.578 – 3.000) : (4.000 – 3.000) = 0.578 : 1.000 = 0.578 = Aii. (2.46 – 2.45) : (2.50 -2.45) = 0.01 : 0.05 = 0.20 = Biii. 2.45 = 219.8 – {(219.8 – 216.8) x A} = 218.066 = C

iv. 2.50 = 226.0 – {(226.0 – 223.0) x A} = 224.266 = Dv. 2.46 = C + {(D – C) x B}

If you do the right calculation the result should be 219.306.

Regards,Surveyors

20. tunJul 14, 2010 @ 09:26:04

Dear SIR,

i WILL WRITE AGAIN

3.0m 3.578m 4.0m

2.45 219.8 216.8

2.46 ????

2.50 226.0 223.0

21. tunJul 14, 2010 @ 09:23:32

Dear Sir,I would like to know tank sounding calculation formular.

sounding 2.46 m and trim 3.578 correction is = 0

3.0m 3.578m 4.0m2.45 219.8 216.82.46 – ??? -2.50 226.0 223.0So how to gat for value for 2.46 m ,trim 3.578m ???

Best regards,Tun

22. Y B DJul 11, 2010 @ 14:42:37

Grateful if you could post a Draft Survey Calculation for a vessel with draft marks and hydrostatic tables in Feet & Inches.

23. surveyorsJul 07, 2010 @ 01:45:30

Dear Tun,

Thanks for self-solving your previous two questions.

As Terms : Ton Per Cm Immersion (TPC) the number of metric tones required to change the mean draft of a vessel by 1 centimeter.By means, every centimeter of ship’s draft going up or down on to the water will count by Metric Ton.For example : Ship’s Mean Draft is 5.55 M, TPC is 49.00 MT. When the ship’s mean draft is change to 5.56 M, means the ship has received the load quantity 49.00 MT onboard.

Regards,Surveyors

24. surveyorsJul 07, 2010 @ 00:46:31

Dear Pankaj,

Thanks for your question. The Ship Beam is the same meaning with Ship Breadth or Ship Width.

Regards,Surveyors

25. tunJul 02, 2010 @ 16:26:51

DDEAR SIR,

ABOVE TWO QUESTIONS,WE FOUND AND UNDERSTOOD,BUT WE DID NOT UNDERSTAND IS TPC CORRECTION ,SO HOW TO FIND OUT IT.

BEST REGARDS,TUN

26. tunJul 02, 2010 @ 15:10:31

Dear Survyor,

Sorry sir We have one more question.

MTC 1 = MMM + 0.5 ( THIS 0.5 IS FROM WHERE,HOW TO GET IT?)

THANK YOU VERY MUCH FOR YOUR REPLY,WE ARE WAITING YOUR REPLY.

BEST REGARDS,TUN

27. tunJul 02, 2010 @ 11:17:27

Dear Surveyor,

Please explain to me above calculation .We do not understand one point TRUE DRAFT AND TRUE TRIM

HOW GET (Fc is (_ 0.004m) ? From Draft correction to distance to Perpendicular calculation Fc is ( 0.004M)Please explaine to me ( _ 0.004m)

Best regards,Tun

28. pankajJun 22, 2010 @ 17:11:40

I am junior surveyor struggling to learn draft survey . so please u tell me what is the meaning of ship beam.

29. surveyorsMay 12, 2010 @ 19:02:01

Dear John,

I have explained it on last post “Draft Survey Procedure and Calculation”. Just take a look back.

Regards,Surveyors

30. johnMay 10, 2010 @ 23:16:22

Good day. I am a junior surveyor struggling to learn draft surveyI would like to know the formula to calculate especially

LBM: length between markFD “ Fore distance to perpendicular:AD : after distance to perpendicular:Thank you very much indeed

31. surveyorsMay 01, 2010 @ 18:10:17

Thanks Leyden,

I will post it once available. Keep in touch,

Rgds,Surveyors

32. leydenApr 28, 2010 @ 11:25:17

nice specimen , have any specimens on grain loading calculations . It wud be gr8.

33. SadanandApr 23, 2010 @ 21:03:13

Dear Surveyor,

Thank you very much for the explanation.

It was brilliant and proves that you have incredible experience.

I have used Draft survey Lt which is freely available in google and easily downloadable. Please try it and post your comment on this software.

Can you please let me know or post a specimen of calculation fordetermining corrected sounding from the one physically observed on thetank using a tank capacity table. I have never seen a tank capacity table.

Best Regards,

Sadanand

34. surveyorsApr 21, 2010 @ 11:06:00

Dear Sadanand,

The VEF is a compilation of the Total Calculated Volume (TCV) measured on the vessel and adjusted for On Board Quantity (OBQ) or ROB (Remaining On Board), and then compared against the shore TCV.

The adjusted vessel TCV is divided by the shore TCV to obtain a voyage VEF for each voyage. The sum of all the qualifying vessel VEF’s are averaged to obtain the VEF.

A VEF(L – Load) should be developed at the load port using only load port TCV’s and discharge VEF(D – Discharge)’s should only use discharge port TCV’s. All voyages should be listed starting with the most current and working backwards.

Even voyages that do not meet the qualifying voyage criteria should be included. A minimum of five qualifying voyages must be used to obtain a workable VEF.

Voyages prior to structural changes that affected the vessel’s tank capacity should be excluded. Voyages with no shore side measurements should also be excluded along with any voyage that is not with in +/- 0.3% of the average ratio of all voyages listed.

I have put downloadable pdf file regards to this matter on the download box.

Regards,FaisalSource: John A. “Jack” Szallai – Orion Associates L.L.C.

35. SadanandApr 20, 2010 @ 20:23:36

Dear All,

Please can anyone brief me about V.E.F.(Vessel Experience Factor) ?

Regards,

Sadanand

36. cristianApr 16, 2010 @ 19:01:05

Still waiting for the draft survey program.

37. surveyorsMar 25, 2010 @ 12:53:14

Thanks Phlom,

You could send any materials related to marine survey and surveyor that you have to my email. I will published it on my blog.

Regards,Faisal

38. PhlomMar 25, 2010 @ 04:50:27

I am back. If is any study material that i can send it to you just mail me and i’ll look for it. They are .pdf and .doc.I was to my first draft survey. As observer…cause i am still learning :d But it was really interesting. And i used youre specimen as example and it was very good. So thx!

39. surveyorsMar 18, 2010 @ 10:06:06

Dear Phlom,

Thanks, if you have any related articles you could send me one.

Best Regards,Faisal

40. surveyorsMar 18, 2010 @ 10:03:56

Dear Chistian,

Thanks, Yesterday I have discussed by email with my friend Ronald, he told me that he will launch the New Draft Survey Program. For pre-launching, he will be given the raw program in excel to attach on my blog for reviewing by the blog visitors.

On the last mail, he said that the download link will submit to me on the next 14 days. Then I will post it here. Hope it could be done.

Regards,Faisal

41. surveyorsMar 18, 2010 @ 09:30:17

Dear Joseph,

Welcome, the Draft survey is the same with others science, where everybody can do it as long as he/she has been wilfulness to learn it.

Draft survey would be more prefer for seaman or the person who has experienced with ship, cargo and port. Firstly, you should need more effort to learn about basic knownledge of the characteristics, specifications, descriptions and terms among them. Then practising the theory you have got is the best way to improve your skill.

Is there any feedback for Joseph? Just leave your comments!

Regards,Faisal

42. PhlomMar 18, 2010 @ 04:11:18

Hy there! Thanks for this specimen. It is really useful. Hope it is more to come.Ia’su!

43. cristianMar 17, 2010 @ 22:15:53

Somebody has a basic draft survey programme (in excel for example)?

44. JOSEPH CHRISTIAN ACQUAHMar 15, 2010 @ 23:20:37

I am an Accountant. I want to study Draft Survey and Bunkers.Any Special Help?

45. surveyorsFeb 10, 2010 @ 13:07:41

Dear Sadanand, will post it shortly.. Thanks.

46. SadanandFeb 09, 2010 @ 20:23:04

Please give specimen report for survey of liquid surveys such as phosporic acid and also explain the derivation for Vessel Experience Factor(V.E.F.)

Draft Survey: The Accuracy and Factors Effecting

Jan 22

Surveyorsdraft survey, marine surveyor draft survey 2 Comments

Sometimes the accuracy of Draft Survey is a big question, especially when the cargo loaded or discharged from the vessel shown extremely different weight with the references Weight Scale or Counter Weight. Unfortunately, the parties concerns would be doubt on to the weight resulted by Draft Survey, as they have been relying upon the mentioned scales for many years.

Draftmark

The Draft Surveyors as the person in charge should be solve this issue to prevent any claim in the future. Where is the doubt came from? The next investigation is required to calm down these issues.

Draught Survey UN ECE: Code of Uniform Standards and Procedures

UN ECE was published the Factors Affecting Draft Survey as follows :

1- Incorrect hydrostatic information or draft marks: Investigations carried out in specially performed draft surveys have indicated that there can be significant errors in the determination of displacement due to typographical errors or arithmetical errors in the ship’s hydrostatic tables. This could be improved if the tables furnished to the surveyor bore an approval stamp by the flag government or the classification society. A number of years careless re-painting of draftmarks, especially if they have not been permanently marked on the hull, can cause erroneous readings. If there is any doubt, the draft marks should be re-sited at the next dry-docking.

2- Incorrect tank calibrations: This is normally ascertained after a number of draft surveys when a constant error may appear. It may be verified by a carefull draft survey when just the tank(s) in question are filled or emptied with no other weight changes. Clasification societies, upon request of the shipsowners, may however issue the special calibration certificates for each compartment of the vessel.

3- Mud and/or scale in ballast tanks: The quantity of mud and/or scale will increase over a period of years, depending on the sediment in any ballast taken, on the extend of scale formation and on the cleaning which is carried out. It is very difficult to quantify. The effect on ballast calculations can be minimized unless there are reasons to the contrary by leaving a measurable quantity of water in the ballast tank instead of pumping it dry. The calculation would then use a difference in known water quantities rather than assume that a tank is completely empty : in this way the error would be confined within the density differential of the mud and the ballast water. Regularly large bulk carriers arrive at unloading ports with a slight trim by the head as a result of burning fuel from the aft located fuel tanks during long sea passages. Since generally the sounding pipes

are located aft only, dry soundings of ballast tanks do then not necessarily mean that no water is present, since any water will accumulate in the fore end. When the ballast tables are subsequently entered with zero sounding and the head trim, considerable quantities of residual ballast water are found. Again, this water does not actually have to be present. Consequently, when one assumes empty or tabulated quantities, both may be wrong.

4- Bottom shell growth: Marine growth on the bottom of the ship, especially if dry docking is delayed or if there is a failure in the anti-fouling paint, adds weight to the ship. But, because this weight should not change between the start and finish surveys, it has no effect on the calculation of the cargo weight, unless the vessel is docked for a long period or the antifouling paint deteriorates.

5- Water disturbance: Normally due to wind, swell or passing traffics. Accurate reading of the draft requires the use of a draft reading tube.

6- Variations in seawater density: If a loaded vessel has a small underkeel clearance, the seawater may hold mud/sediment in suspension, or chemicals in solution could effect its density. This may be apparent from the bottom layer sample. If it is suspected, a sea water sample should be taken from the maximum draft as a check. In river ports or in proximity of river mouths or of industrial plants, there may be numerous layers of water with differing densities, which may substantially affect the accuracy of the water samples unless properly detected.

7- Vessel squat: When a vessel is moored in a tidal stream or a fast flowing current, in shallow water, it will squat in the water, i.e. its draft will increase. This is due to the fall of the pressure of the water between the bottom of the hull and the seabed. The sinkage is due to a number of complex factors due to the hydrodynamic properties of the hull, especially where underkeel clearance is small and which cannot be accurately determined by theoretical calculations. There appears to be no effect at current speeds below 2,5 knots. If conditions are inductive to squat, the surveyor and the master should monitor carefully that the vessel is fully afloat and not touching the bottom and for best accuracy, consider waiting for slack water, or shifting the vessel to another berth where the effect of squat are known to be less or absent.

8- Asymmetrical hull deflections: If the mean draft midships differs from the mean of the forward and after drafts, it is assumed that the deflection of the hull shape takes the form of a parabolic curve. This assumption is inherent in the two-thirds and quarter-mean methods of correcting for hull deflection. If there is no difference between the mean draft midships and the mean of the forward and after drafts, it is assumed that the hull shape has not been deflected. Both assumptions may be incorrect. In practice, the hull deflection may not be a parabolic curve or there may be deflections between the ends of the vessel and the midship points (i.e. as a modified sine curve). If the draft is not read at all six draftmarks, the hull may be twisted without the fact being known.

9- Solar bending: Vessels of approximate 50.000 mt deadweight and upwards, may be subject to hull deflections caused by solar bending of the deck and structure above the waterline. The effect would normally be a hogging which can be appreciable. Some readings taken on a 74.000 mt dwt bulk carrier and reported in “Seaways” (March 1987), showed that the fully loaded vessel was

sagged 5 cms at 07.00 hrs and 27,5 cms at 17.00 hrs on the same day with no movement of weight within the vessel (apart from normal oil/water consumption for an anchored vessel).

10- Use of approximate methods for corrections: The mathematical methods used to correct for trim and/or hull deflections, if these conditions exist, are approximations because of limitations of time, expense and the work site. However, if the same methods are correctly and uniformly employed in all surveys, the resultant error in the exact cargo weight will be minimal. However, if in better equipped ships, correction tables for trim and/or hull deflection are available, then such tables should be used instead of the approximate methods.

11- Draught gauges: Draught gauges may be very helpful as a check, but should never replace the reading of draughts using the fixed draught marks on the ship’s hull.

12- Squat: While measures the draught, when there is a strong current running and there is water depths of less than twice the draught of the vessel, the draught readings may be misleading, due to the effects of squat. The survey report should include reference to Possible Squat Effects, even if a suitable correction to the draught readings cannot be determined.

13- Anchors and Chains: The anchors may be in the housed position, where they contribute to the lightship, or they may have been used in the mooring of the ship. Then the anchors will be on the sea bed along with a given length of cable. The loss of weight due to its removal is weight taken from the light displacement, this amount should therefore be added to the quantity of cargo. There should be information available on board to enable the surveyor to establish or calculate the weight of the missing anchor and cable.

In case of the chain cable, it can be calculated with reasonable accuracy by the following formula:

Weight per shackle (Tonne)  =

15 x (link diameter in cm)2 x 3,87——————————————1000

The link diameter is the diameter of the steel rod, which makes up each individual link. In the case of the anchor itself, this will vary from ship to ship, but this information should be available on board. This anchor weight should be rounded to the nearest half tonne.

Draft Surveys – Volume And Weight Calculations:Draft Surveys are to determine the quantity of cargo loaded in, or discharged from a vessel or barge and are dependent on the fact that the vessel or barge is always afloat, and that all the drafts are visible.  Some of the common problems during draft surveys one should always be aware of are:* Unusable sounding pipe – i.e., inaccessible, blocked or broken* Ballast holds, which are poorly calibrated* Tunnel space/duct keel that cannot be sounded

* Loaded vessel aground prior to commencement of discharge* Loaded vessel aground after completion of loading prior to sailing* Listed vessel, which has its effect on displacement and soundings of liquids in tanks and other spaces* Weights other than the cargo, ballast, or consumables that are not the same between the starting and the finishing surveys.

Surveyor’s opinion:

All the above are very clear explanations and guides. Additionally, Surveyors has concerned to Draft Mark Reading. Draft Mark reading is the essential part of Draft Survey, where the Draft Survey is begin from the reading part. The vessel’s staffs cooperation is needed to success the good reading. The following are some rules to get the best result :- Vessel is secured properly,- No any ship’s gears movement allowed at the time, (such as crane, derrick etc),- No any ship’s liquids transfer activity allowed during reading, (ballast, fresh water, fuel and diesel oil),- Read the Draft Marks as close as possible, taken pictures for the next clarifying,- Use the small boat to read close the Draft Marks, do not see it from the ship’s maindeck,- Find the draft in meter first then continue with centimeter to prevent big error.- For the heavy swell sea condition it is recommended to read and record 12 times, taken out 1 biggest and 1 smallest of the reading results, and make an average draft from the 10 results remained.

To know more, kindly refers to the previous post of Draft Surveys : Terms of Conduct, Procedures and Calculation, and Specimen of Calculation.

Do you have any issues regards this? please drop down your comments here.

Regards,

Surveyors

Bunker Survey Calculation Software for Surveyor

2 Comments (+add yours?)

1. SurveyorsFeb 16, 2011 @ 15:48:56

Dear William,

Thanks for your comments.

Regards your comment, I have some collected information.

It is important to do the sampling to the water where the ship is floating to get its density. The density of the water around the ship could be different because of:- the depth difference- the different places (around the ship) from where the sample is taken.

To avoid incorrect sample taking :- Sample is only effective before/after draft reading.- Don’t do the sampling near the overboard (cooling water/ballast water).- Do the sampling at the seaside. The density at the shore side could be different because the water between the ship and the shore doesn’t move/stagnant.- As soon as the sample is taken, read the density.

- For small ship < 10,000 DWT : 2 samples, at the sea side near the mid draft, at the depth of 1/3 and 2/3 from mid draft.- for big ship > 10,000 DWT : at least 3 samples, at the sea near the mid draft and at the depth of 1/6, 1/2 dan 5/6 from mid draft.

Mistakes in Hydrometer:- Hydrometer is not calibrated to adapt to sea water pressure.- The temperature around the water is incorrect.- Hydrometer is made of metal or bronze and it can rust.

For additional information, please check the link of The correct use of marine hydrometers at http://www.amsa.gov.au/shipping_safety/marine_notices/2006/Documents/0506.pdf

Regards,Surveyors

2. William E. GeorgeJan 31, 2011 @ 02:34:28

Draft Surveys and Water Density, any comments or thoughts?

I have done many draft surveys against shore scales. On Panamax size vessels with a draft of 13 meters, I have found that the averaging of water densities, namely the top, middle and bottom draft can give poor results because a wall sided ship displaces the water down like a piston. To get great results it is best to use the density of the water under the vessel. Sampling using the emergency fire pump seems to work just fine.

Keep this in mind if a ship’s displacement is 75,000 MT it displaces over 75,000,000 liters of water. Just using a 1.5 liter capture device is not adequate. For every 0.001 error in the density reading will be equivalent to a 1 cm error in draft reading. If there is a difference between the surface water density of 1.020 and bottom density of 1.023 at 13

meters the error will be equivalent to 3 TPC or about 195 MT light if the surface water density is used.

Poor samples can be attributed to poor sampling devices and lack of knowledge.

Another thing to think about is that there is no friction on the immersed sides of the vessel, so while there is great pressure normal to the surface of the side there is no buoyant support because this is no friction on the side of a vessel in still water. The only force that supports the vessel is that upward force on the bottom plating. Here to there is no friction, however the upward buoyant force is supporting the downward force of the ship weight.

I am William E. George, the author of Stability and Trim for the Ship’s Officer, 4th Ed., 2005, which is a United States Coast Guard License Exam Reference for Ship’s Officers in the United States.

Bunker survey

How to Conduct Bunker Survey

Feb 22

SurveyorsSurveyors bunker survey, marine survey 11 Comments

What is Bunker Survey? The survey is carried out to measure and ascertain the quantity of Bunker onboard at the specific time. This survey is produced the report that states the amount of bunker, usually Fuel Oil (FO) and Diesel Oil (DO), and sometimes Lubricating Oil (LO) is included.

Go Sailing

Commonly this is done prior to and after a time charter period than mentions as On Hire Bunker (prior) and Off Hire Bunker (after), the Bunker Survey is required to check the amount Bunker transferred or supplied onto the Ship’s Tanks. This job is associated with Ship’s Chief Engineer, the Person who responsible for bunker onboard.

In this post limits to how to conduct the Bunker Survey on the ship tanks only.

Survey Tools required for Bunker Surveyor

-        Notes Book,

-        Sounding Tape,

-        Thermometer,

-        Density Meter for Oil (0.750 -1.000),

-        Oil and Water Paste,

-        Petroleum ASTM Table 54B (for Product Oil) and Table 56,

-        Google and Glove,

-        Flashlight,

-        Sampling Can,

-        Bottle or Can for Sampling (if required taken samples).

Steps for Conducting Bunker Survey

-        Identify and records the number and Depth of Tank, Reference Height, and Measuring Method recommended to use (Ullage or Sounding) for each Oil Tank. Sounding is determined the level of liquid tank from the bottom of the tank to the liquid surface (typically applied for light liquid). Ullage means to determine the level of liquid of tank by measured the empty space from top of the Tank (the mouth of Sounding Pipe) to the liquid surface (typically applied for heavy liquid). The both methods will point to the same result.

-        Record the Last Bunker Report, Time and Place of last Bunker supplied, includes the Oil density.

-        Records the quantity of bunker onboard when the ship arrives at Port (arrival Condition) as per Engine Log Book.

-        Checking the accuracy of the Sounding Tape, it is recommended to use your own Sounding Tape. In case we used Ship’s Sounding Tape, please checking the tape.

-        Sounding each Oil Tank and records the level of Oil on the tank. Attached the sounding Tape with Oil Paste to make easy and clear to show of oil level (recommended for Light Oil).

-        Check the Ship’s Draft Marks to get the Ship Trim for Trim correction, and check the ship Inclination or Listing for List Correction, that is required to calculate the Tank Quantity Table.

-        Taken Oil sample, check temperature and oil density, for the accessible tank only. The Service and Settling Tanks are not accessible due to the oil on that tanks were in heating condition at the high temperature. We could records the tank gauging for determining the quantity, the temperature at the thermometer available on each tank, and the Oil Density from the Engine Log Book. If you could not taken the oil sample for checking density, it is recommended to calculate the Density Commingle, by means the Combine Density between two Oils (Old and New Oils) that has mixed on one tanks which they have different in Density. Where it is approaching the actual oil density, the pattern is {(Old Oil Quantity x Oil Density / Total Oil on Tank) + (New Oil Quantity x Oil Density / Total Oil on Tank)}.

-        Calculations, this stage will involved the Sounding level of each tank, Ship’s Trim and List, Tank Quantity Table (provided by Ship’s Chief Engineer), Oil Density and Temperature, ASTM Table 54B to ascertain the Volume Correction Factor (VCF – to convert from Cubic Meter to Kiloliter) and ASTM Table 54B for Weight Correction Factor (WCF – to convert from Kiloliter to Metric Ton).

-        Example to calculate Density Commingle: FO Tank No. 1 C, total oil on tank 400 Cu.M, Old Oil 200 Cu.M with density 0.9870, and New Oil 200 Cu.M with density 0.9720. Density Commingle = {(200 x 0.9870 / 400) + (200 x 0.9720 / 400)} = 0.4935 + 0.4860 = 0.9795.

-        Issued the Tank Sounding and Bunker Report.

I think now you could conduct Bunker Survey, the Detail of Bunker Survey Calculation will be post shortly. Let me know if I miss something by your comments and feedbacks.

Regards,

Surveyors

In my last post How To Conduct Bunker Survey , I have explained the general step for Bunker Survey conducts. Now, the topic is about the way to calculate ship bunker that we have found on the ship tanks. It is suggested to read the last post to become familiar with calculation.

Bunker Survey

The bunker calculation is simple and needs the following:

- Tank Sounding data and Tank Capacity Table. The Corrected Sounding means below is the sounding after correcting with vessel’s trim and list.

- Temperature of Oil on Tanks,

- Oil Density @15C,

- Table ASTM 54B (VCF) and Table ASTM 56 (WCF).

Now we could go with sample of 1 tank to test the calculation.

** Question :

FO Tank No. 1 Center, Corrected Sounding = 3.27 Meter, Temperature = 34 degrees celcius, Density @ 15 C = 0.9870.

Tank Volume at Sounding 3.20 M = 157.20 Cubic Meter, at Sounding 3.30 M = 163.60 Cubic Meter.

** Answer :

- The Quantity in Metric Ton = Oil Vol x VCF x WCF,

- Observe Volume = {(3.27 – 3.20) / (3.30 – 3.20) x (163.60 – 157.20)} + 157.20 = (0.07/0.10) x (6.40) + 157.20 = 4.48 + 157.20 = 161.68 Cu.M.

- T 54B (VCF) > Density @ 15C 0.9903 at 34 C = 0.9870 (see the picture below you need to interpolate if any different numbers on both columns).

 

ASTM Table 54B

- T 56 (WCF) : Density @15C 0.9903 at  34 C = 0.9892 (Quick formula with reducing factor for WCF is Density @ 15C – 0.0011 = 0.9903 – 0.0011 = 0.9892). We don’t need to see the table anymore.

- So, The Quantity in MT is 161.68 x 0.9870 x 0.9892 = 157.85 MT. Sample calculation tanks sounding attached below.

Tank Sounding

Note : If you do calculation with Volume in Barrel, just uses ASTM Table 6B for VCF, ASTM Table 11 for WCF in Long Ton and then ASTM Table 13 for WCF in Metric Ton.

Just drop your comments around this topic.

 

Regards,

Surveyors

How to Conduct Bunker Survey Draft Survey: The Accuracy and Factors Effecting

53 Comments (+add yours?)

1. SurveyorsFeb 17, 2011 @ 10:00:26

Hi Korso,

The copies you meant is not legal copy to distribute, you should order it from ASTM website.

For references, I have load the simple program for ASTM table, you could check at software page. Hope you can work with it.

Regards,Faisal

2. SurveyorsFeb 17, 2011 @ 09:23:15

Hi Naina,

Sorry for late reply. I have some assignments to do.

The calculation presented on the post is for general use, there is no different way to calculate between small ship and big ship.

Regards,Surveyors

3. SurveyorsFeb 17, 2011 @ 09:19:39

Dear Paul,

You may take long distance course for marine survey at IIMS (international Institute For Marine Surveyor). please check the site http://iims.org.uk for more detail.

Regards,Faisal

4. SurveyorsFeb 17, 2011 @ 09:16:59

Hi Evgeny,

Thanks, it is correct when the temperature at 31 and density 0.9905 you will get VCF at 0.9891.But I was made the calculation at temperature 34 and density 0.9903 where the VCF is 0.9870.

You could check the software page where I have load table 54B program, hope it useful.

Regards,Faisal

Regards,Faisal

5. SurveyorsFeb 17, 2011 @ 09:11:13

Hi Zakir,

Thanks for commenting.

Regards,Faisal

6. KORSO T. ILIESFeb 13, 2011 @ 21:50:55

Hi, I’m a young marine surveyor from algeria, and I would thank you verry mutch for all the informations you’re provinding us with, in fact the country were I am information are practically not available at all, and I would like to ask you if you can provide me with a copy of Table ASTM 54B (VCF) and Table ASTM 56 (WCF), that would help me verry mutch,many thanks in advance,and have a nice swell,

best regards

7. MohamedFeb 08, 2011 @ 12:41:10

Dear Surveyors

I am not suveyor, I hv been working as Executive Operations in a shipping company since 2006. I would like to know how to calculate bunker in tug boats with the BHP 2500 to 4000 BHP. and also pls guide to me to calculate Draft survey of barge from the capacity of 5000 DWT to 20,000 DWT.

I hv been assign to give presentatino about these two by Thursday.

Your kind help in this regard is highly appreciated.

RegardsNaina

8. Paul OkunehFeb 06, 2011 @ 04:09:51

Thanks very much for your concern in educating people freely. I need your advice on the best certification I should go as regards Inspection Jobs. I am a Nigerian.Regards.Paul Okuneh

9. EvgenyFeb 05, 2011 @ 09:36:00

Dear Faisal,

Good day!

You have a mistake VCF in example table and as a result next steps of calculation is wrong. As per API MPMS Chapter 11.1 (ASTM D 1250-04 and IP 200/04), Table 54B for your density +15C 0.9905 and fuel temp. +31C the true VCF is 0.9891.

Best Regards,

10. zakirFeb 01, 2011 @ 16:23:27

I am switching from sea to shore job as a bigginner in ship survey your works and comments will be of good help for me. Thanks for your valuable contribution in sharing knowledge for the advancement of the shipping industry in the area of surveying

11. SurveyorsFeb 01, 2011 @ 16:03:51

Thanks Capt. Miguel.

12. SurveyorsFeb 01, 2011 @ 16:03:17

Thanks Gouanfo,

Welcome onboard of Marine Surveying. You could contribute your sea experience here.

Regards,Faisal

13. gouanfo innocentJan 26, 2011 @ 18:45:58

as I am switching from sea to shore job as a bigginner in ship survey your works and comments will be of good help for me. Thanks for your valuable contribution in sharing knowledge for the advancement of the shipping industry in the area of surveying

14. CAPT. MIGUEL SAIZ MONROYJan 26, 2011 @ 01:32:52

VERY GOOD INFORMATION …THANKS A LOT….INDEPENDENT SHIP & CARGO SURVEYOR – CURRICULUM VITAECapt. ( r ) MIGUEL SAIZ MONROY ( Lic. No. 17085010 – DIMAR –Col.).MARINE SURVEYOR, ISM & ISPS INSPECTOR CONSULTANT, MARITIME INSPECTIONS, DELIVERY / REDELIVERY, BUNKER SURVEYS, DRAFT SURVEYS, PORT CAPTAIN, PORT OPERATIONS, CARGO INSPECTIONS, CONDITION SURVEYS, ON HIRES / OFF HIRES IN COLOMBIAN NORTH PORTS.-

Capt. ( r ) MIGUEL SAIZ MONROY – surveyorsaiz@hotmail.com; http://surveyor2007.spaces.live.comC. de C. No. 17085010 de Santa Fé de Bogotá, D.C. – Licencia de Navegación No. 17085010 – D I M A R – COLOMBIAN I T No. 17085010 – 0 – Régimen SimplificadoTel / Fax No. 5 7 5 – 3 0 1 5 9 7 5 – M o b i l e s: 3 0 0 8 0 2 6 7 6 7 y 3 0 0 8 0 3 7 2 0 7 – VHF Ch 16Calle 72 No. 39 – 222 – Piso 2 – Carrera 41 No. 71 – 79 Piso 2 – Barranquilla – Colombia – S.A.

15. SurveyorsJan 22, 2011 @ 13:05:14

Thanks Vasim,

Hope you could help the other surveyors.

Regards,Surveyors

16. Vasim A.S.Jan 14, 2011 @ 19:06:25

Dear all Surveyor’s……

If u want any kind of imformation or problem in calculation or any dout …. I will sol for u people….Contact me on :- vasimjam@yahoo.co.in

17. captaoufDec 27, 2010 @ 01:43:24

that in a report i must mention the amout of the damageexemple the collision between the ship and the tugboat

18. SurveyorsDec 08, 2010 @ 14:29:43

Dear Erwin,

Thanks. Yes, it is the easiest way to do draft survey.

Best Regards,Surveyors

19. SurveyorsDec 08, 2010 @ 14:25:35

Dear Silvio,

Yes, you need to attach Table ASTM 54B for the calculation program.

Regards,Surveyors

20. SurveyorsDec 08, 2010 @ 14:21:00

Dear Ali,

I will post it shortly.

Regards,Surveyors

21. erwinDec 05, 2010 @ 12:01:12

dear surveyor,

if found no trim and hell correction, we just only make vessel on evenkeel and going to calculated the quantity.

tks

22. silvio duarteDec 01, 2010 @ 01:15:57

dear sirs

We need information on discharging supervision of marine bulk oil, in connection with ullaging of ship’s tanks and quantity calculation. The computer system will be needed together with table ASTM 54B.Could you please revert on this issue.

23. capt yacineNov 26, 2010 @ 23:26:07

draft survey: 2 em trim correction:

what the precedure the found 2 trim correction the are 2 methode i want now secon d methode for second trim correction thank

24. ali husseinNov 24, 2010 @ 05:44:56

Dear Faisal

Could you please, send me and explain the wedge formula.

Thanks in advance

yours faithfully

25. SurveyorsNov 02, 2010 @ 13:54:35

Mr. A,

The Bunkering Process is commonly as the transfering oil from one ship to another. The process is simple, the feeder ship or barge that carried oil, will be alongside at the ship that needs the oil (lets say it mother). After alongside, the feeder will prepare the pump and hose to connecting to the mother ship manifold. The mother tanks and/or flowmeter is checked and prepared by the ship crews. When all preparation is completed, the feeder will start to pump the oil to the mother tank as amount agreed. The quantity agreed could be ascertained by sounding or pointed by flowmeter. After completing the transfer, the tanks or flowmeter will re-check to get the quantity. Then the feeder cast off.

Regards,Surveyors

26. Mr.AOct 29, 2010 @ 18:30:09

sir i need to know about bunkering process in detail…….

27. SurveyorsOct 20, 2010 @ 13:53:10

Dear Tyler,

Thanks for your correction, it was mistyped and should be 3.20. I have changed it on the mentioned post.

Regards,Surveyors

28. tylerOct 20, 2010 @ 02:25:35

thanks very useful step by step but please explain why you use 3.05 (where does it come from) in below part

Observe Volume = {(3.27 – 3.20) / (3.30 – 3.05) x (163.60 – 157.20)} + 157.20 = (0.07/0.10) x (6.40) + 157.20 = 4.48 + 157.20 = 161.68 Cu.M.

29. VINAYOct 20, 2010 @ 02:17:30

Hi

30. SurveyorsSep 27, 2010 @ 13:12:01

Hi Ixora,

The ullage and sounding are only the method to find the level of liquid on the tank. After finding the liquid level, you could use the calculation for both with same formula.

Regards,Faisal

31. fatihahSep 26, 2010 @ 16:09:15

dear Faisal,

it is this bunker calculation can be used in ullage or sounding calculation.

32. SurveyorsAug 08, 2010 @ 11:55:42

Dear Nash,

Thanks for feedback. The 34C should not be there, I have make mistyping.

Regards,Surveyors

33. nashAug 01, 2010 @ 01:24:59

hello surveyors,

i do understand everything but , i dont understand is how ure getting the 0.9892@34 C, you have not shown the T56 table here its very confusing here with WCF. WITH REFERNCE TO THE EXAMPLE ABOVE IVE COPIED THE CONFUSING PORTION BELOW

“”T 56 (WCF) : Density @15C 0.9903 at 34 C = 0.9892 (Quick formula with reducing factor for WCF is Density @ 15C – 0.0011 = 0.9903 – 0.0011 = 0.9892). We don’t need to see the table anymore”"

34. SurveyorsJul 30, 2010 @ 02:20:49

Hi Rahdian,

Thanks, you also could send your contribution for this blog.

Have a nice day as well.

Regards,Surveyors

35. RahdianJul 28, 2010 @ 16:49:54

Hi Faisal,You are great, you give a good contribute for as .

Have a nice day

36. SurveyorsJul 26, 2010 @ 22:12:58

Hi Reene..

Please be noted that the author of this blog is Surveyors / Faisal not Sadanand as you are mentioned.

Regards,Surveyors

37. ReeneJul 24, 2010 @ 03:16:40

oh sorry my mail ID is : reene50@ymail.com

38. ReeneJul 24, 2010 @ 03:15:33

Dear Sadanand,

I need soft copy of this ASTM table . Could you please send me this ASTM54B Table softcopy. Plz…in the image above I couldn’t see any values. I need this table very urgent. Plz send me soon. It’s request from me.

39. sankadioJul 24, 2010 @ 01:43:30

good calculation

40. surveyorsJul 07, 2010 @ 01:04:13

Dear Indran,

I have published two posts about bunker survey, you could re-read http://sevensurveyor.com/2010/02/22/how-to-conduct-bunker-survey/ and http://sevensurveyor.com/2010/03/27/bunker-survey-calculation/.Then you could download at downloading sidebar on my website the “Bunker survey guide.pdf” and “MEASUREMENT OF PETROLEUM ON BOARD MARINE VESSELS.pdf”.The four resources is good enough to guide you for conducting bunker survey.

If you are serious, you could learn by joining the survey company in your country as well.

Regards,Surveyors

41. surveyorsJul 07, 2010 @ 00:38:30

Hi Aly,

I have ever answers the same comment as you had. Kindly check one of the comment at post Draft Survey Procedures and Calculation >> http://sevensurveyor.com/2009/08/25/draft-survey-procedures-and-calculation

Regards,Surveyors

42. indranJul 02, 2010 @ 20:08:41

Dear sir,

I just starting to learn how to conduct bunker surveying , give some info from where i start.

Thank youindran

43. aly husseinJun 17, 2010 @ 19:31:06

Dear Surveyor,

thank you indeed for Your contribution on this site,kindly pls explain, how I can calculate the Trim & List correction of sounding, in case there are no Trim & List correction tables are available on board.

best regards

Aly Hussein

44. surveyorsMay 30, 2010 @ 14:25:22

Daer Abu,

Thanks for your reading and comment.

45. ABU SMITHMay 17, 2010 @ 20:05:16

THANKS FOR THIS INFORMATIONS

46. aly husseinMay 12, 2010 @ 14:46:01

Dear Sadanand

Could you please explain, how you find out the Trim correction & List correction for sounding, in case there are no Trim & List correction tables are available on board.

yours faithfully

Aly Hussein

47. aly husseinMay 12, 2010 @ 14:31:15

Dear Sadanand,

Good dayWay of simple explanation and a wonderful

Regards,Aly Hussein

48. surveyorsMay 01, 2010 @ 17:47:04

Sadanad,

Briefly, I can afford you with the calculation you meant. For the complete one, may be post later.

Example with Capacity Table :Fuel Tank No. 1C.

Sounding : 1.50 M or 1,500 MM.Vessel’s Trim : 1.00 M.Vessel List : 1.0 degree to Starboard Side.

Trim Correction for Tank No. 1C in MM——————————– TRIM ——————————–SOUNDING …… -1.00 / 0.00 / 1.00 / 2.00 / ……. 1.00 …………… -200 / 000 / 200 / 400 / ……. 2.00 …………… -600 / 000 / 400 / 600 / ……. 3.00 …………… -600 / 000 / 600 / 800 / …

List Correction for Tank No. 1C in MM——————————— PORT / STARBOARD ————LIST ….. / 3.0 / 2.0 / 1.0 / 0.0 / 1.0 / 2.0 / 3.0 / …Corr …… 300 / 200 / 100 / 000 / -100 / -200 / -300 /

From the both tables we could get the corrected sounding as below :

Corrected Sounding (CS) = Sounding (S) + Trim Correction (TC) + List Correction (LC)

TC at S 1.50 M and Trim at 1.00 M is 300 MM (by Interpolation)LC at List 1.0 degree to starboard (the right part beside 0.0 degree) is -100 MM.

CS = S + TC + LC.CS = 1500 + 300 +(-100) = 1,800 – 100 = 1,700 MM or 1.70 M.

That’s all..Surveyors

49. SadanandApr 27, 2010 @ 18:22:14

Dear all,

Please explain the specimen of calculation to find out the corrected sounding corrected with trim and list.

Regards,

Sadanand

50. surveyorsApr 14, 2010 @ 08:57:10

Thanks Sadanand,

Hope could find more interesting topic on the next post.

Regards,Faisal

51. SadanandApr 13, 2010 @ 16:36:22

Dear Surveyor,

The above post is excellent and gives a detailed survey procedure.

Your contribution to this site is phenomenal.

Thanks a lot.Best Regards,

Sadanand