competency written examinations chief mate - navigation

Sultanate of Oman

Ministry of Transport and Communications

Directorate General of Maritime Affairs

Competency written examinations

Chief mate - Navigation

Please note the followings;

1 While answering computational questions, all computation steps including formulas, that have led to

the final answer must be shown on the answering sheets to show how the final answer was reached.

2 During computations round up answers for each step to 3 decimal points.

3 In computational questions, for each principle error 50% and for each editorial or mathematical error

25% of the allocated mark for that question or part of question, as the case may be, would be deducted.

4 All answers, with the exception of graphs, sketches and diagrams should be written in black or blue

pen, unless otherwise specified. Answers written in pencil will not be marked.

5 Upon completion of the examination, all rough papers used for pre-calculation or other purposes

should also be attached to the answering sheets and along with question paper handed over to the

invigilator.

6 Any unauthorized materials, such as books, paper, documents, pictures and electronic devices with

communication and/or storage capabilities such as tablet PC and smart watch are not allowed into the

examination room.

7 Mobile phones, if carried shall be switched off. If candidate’s mobile phone is found to be switched

on in the examination hall, the mobile phone will be confiscated and retained for investigation of possible

infringement of the examination discipline.

8 During examination candidates are not allowed to exchange any views verbally or by notes and

should remain silent in order to avoid disturbing other candidates.

9 Any candidate infringing the examination discipline would be asked to leave the examination room,

considered failure in the examination subject and barred from re-examination for a period of maximum 6

months.



Seafarers Affairs Section

Competency Written Examination

Capacity: Chief Mate Examination date: 15.01.2018

Subject: Navigation Time allowed: 3 hours

Attempt all questions

1- (a) SOLAS Chapter V Regulation 34 - Safe Navigation and Avoidance of Dangerous Situations

requires that "An appraisal of all information relevant to the contemplated voyage or passage should

be considered before detailed plans can be drawn up".

(i) state the purpose of the appraisal process; and (2)

(ii) outline what the appraisal process should provide to the Master and the Bridge team.

(5)

(b) The Routeing Charts are produced to assist in appraising and planning ocean voyages.

(i) state FOUR types of information from the Routeing Charts that may be used

during the appraisal; and (2)

(ii) explain how the information from (b)(i) would influence the selection of a route in the

Planning stage of Voyage Planning. (5)

2- With respect to a Tropical revolving storm (TRS);

(a) explain the reasons for the naming of the dangerous semicircle; (3)

(b) draw a cross section through a TRS showing areas of cloud and precipitation; and (6)

(c) describe the signs which give warning of the approach for the TRS. (5)

3- Whilst approaching the Dover Straits on an ore carrier of 100000 GT, in dense fog, the OOW

makes the following observations on the radar (6 Mile Range). The vessel is steering 230°T at 5

knots.

Target A Target B Target C

Time Bearing Range Bearing Range Bearing Range

0910 255oT 5.5 miles 156oT 5.5 miles 350oT 3.0 miles

0916 255oT 4.5 miles 157oT 4.6 miles 350oT 2.6 miles

0922 255oT 3.6 miles 158.5oT 3.8 miles 350oT 2.2 miles

(a) On provided radar plotting sheet complete the plot for all THREE targets. (3)

(b) Prepare a full report on all THREE targets at 0922 hrs. (9)

(c) Determine, for EACH target, the reduction in speed of own vessel, at 0928hrs, that will ensure

the target passes at a distance of 1.0 mile. (3)

Note: assume change of speed has instantaneous effect.

(d) State, with reasons, the actions that should be taken by a prudent Master at 0928 hrs. (4)

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4- A vessel departs Thursday Island, Queensland, Australia bound for Coquimbo, Chile. The Master

wishes to take full advantage of the shortest possible route to Coquimbo, but this Great Circle route

enters the Winter Load Line Zone whose northern limit is 33°S.

After bunkering at Thursday Island, the vessel is overloaded by 420 tonnes of fuel and water which

must be consumed before entering the winter zone, the vessel uses 28 tonnes of fuel and water per day

at her service speed of 14.8 knots.

Departure position Thursday Island, Pilot station 10o 35´ S, 142° 13´ E

Land fall position off Coquimbo 29° 47´ S, 71° 21´ W

Departure time 1000 Standard time, 10 April.

Calculate EACH of the following:

(a) The total distance between quoted way-points assuming that the Master requires the shortest

possible distance that does not contravene Load Lin regulations; and (15)

(b) The Standard Time of arrival, assuming that the vessel maintained her service speed. (5)

5- A vessel is in the North Atlantic, at evening twilight, and is steaming on a course of 224°T at 15

knots and is in DR position 46° 30´ N, 17° 40´ W.

During this period the Officer of the Watch (OOW) obtained stellar observations with the following

results:

The same DR was used in resolving each position line.

Find, by plotting, the vessel’s Most Probable Position at 1832, assuming no random error exists.

(A scale of 1cm = one mile is suitable) (18)

6- With the use of sketches, describe interaction between two nearby ships when meeting end-on; and

in an overtaking situation. (15)

Time Star Azimuth Intercept

1822 A 270° 5.2´ towards

1826 B 143° 7.0´ away

1832 C 175° 4.4´ away

1840 D 330° 6.0´ towards

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1- A vessel leaves Wellington, N.Z., bound for Panama, on the recommended Great Circle route

across the Pacific.

Departure Position off C. Palliser 41° 42´ S, 175° 14´ E

W/P in the approaches to Panama 8° 00´ N, 79° 00´W

Departure time from Wellington is 1830 Standard Time on 24 March.

Given that the extra distance coasting form Wellington to C. Palliser and from W/P 8.0° N, 79.0° W

to Panama is 66 miles, calculate each of the following:

(a) the total distance form Wellington to Panama; (8)

(b) that standard time of arrival at Panama, if the vessel maintains 14.7 knots throughout the

passage; and (4)

(c) the Initial course on departure from C. Palliser. (8)

2- At 1600 UTC on 27th July, a vessel sends a distress message indicating that she is on fire off the

Canadian coast, and is heading to Halifax, Nova Scotia at 9 knots.

The distress call is intercepted by a fire-fighting tug in the vicinity, and she heads on a course to

intercept the casualty to render assistance, at her maximum available speed of 14 knots.

The relevant positions at 1600 UTC were:

Casualty in 42° 06Ń, 59° 17´ W;

Tug in 41° 15Ń, 60 ° 32´ W; and

Halifax pilot station 44° 38Ń, 63° 35´ W.

Calculate each of the following:

(a) The course required of the tug to rendezvous with the casualty, as soon as possible; and

(14)

(b) The rendezvous time, UTC. (4)

3- With respect to weather routeing describe the;

(a) Methods of constructing a least time track; (6)

(b) Types of routeing services; and (4)

(c) Ship’s performance curve limitations. (6)

4- Explain the dangers related to ship-tug interactions. (12)

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5- A vessel is proceeding at 12 knots on a course of 065°T in restricted visibility, estimated to be

approximately 1.0 nautical mile.

The OOW commences plotting three targets, on the 12 n.ml range, at 0006 hours and the resultant

plot completed at 0018 hours is shown on Radar Plot - 4.

(a) Complete the plot for all 3 targets.

(b) Determine each of the following:

(i) course and speed of Target A; (2)

(ii) course and speed of Target B; and (2)

(iii) CPA, TCPA and speed of Target C. (3)

(c) Determine the alteration of course required at 0024 hours to allow Target B to pass clear with a

CPA of 2 miles. (4)

(d) At 0024 hours the OOW alters course 60° to starboard, maintaining a speed of 12 knots.

Comment on the action taken by the OOW with reference to Rule 19 of the COLREG. (4)

(e) At 0027 hours the vessel is settled on a course of 125° T and the following information is

obtained from Target C;

Time Range Bearing

0027 6.1 N.Miles 228o T

0033 5.1 N.Miles 228o T

0039 4.1 N.Miles 228o T

Determine what action, if any, has been taken by target C. (3)

(f) State, with reasons, what action should be taken by the OOW at 0039 hours. (4)

6- State briefly the information content in following publications;

(a) Mariners Hand Book; (3)

(b) International Code of Signals; (3)

(c) IMO Ship’s Routeing; and (3)

(d) Sailing Directions. (3)

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MohammedSha

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RADAR PLOT - 4

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Scale = 12 Nautical miles

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1- On departure, a 190 meters’ bulk carrier with summer displacement of 102000 tonnes, has

overloaded her Winter load displacement by 324 tonnes and the daily consumption is 36 tonnes per

day. The boundary between the summer and seasonal Winter Zone lies along the parallel of 32°S.

The charterers ask the Master to follow the shortest legal route between the following departure and

landfall positions:

Departure position 23° 29'.0S, 070° 25'.0W

Landfall position 27° 30'.0S, 153° 00'.0E

(a) Calculate the shortest legal distance between the departure and landfall positions if the

vessel’s service speed is 15.5 knots. (18)

(b) Explain why it would not be possible to do a direct great circle track, between the departure

and landfall positions, at any time of the year. (2)

2- With respect to weather routeing describe the;

(a) Purpose of routeing; (3)

(b) Types of routeing services available; (3)

(c) Information required by shore organization for providing routeing services; and (3)

(d) Ship’s performance curve limitations. (3)

3- A vessel is proceeding on a course of 213°T at 16 knots in the Northern Atlantic is in DR

position 42° 54'N, 39° 30'W.

Stellar observations were taken with following results using the same DR position for all

observations:

Find by plotting, the vessel’s most probable position at 1800, assuming no random error exists.

(a scale of 1 mile = 1cm is adequate) (18)

Time Star Azimuth Intercept

1740 A 170° 2.5´ towards

1750 B 119° 1.5´ away

1800 C 333° 3.7´ away

1805 D 025° 10.5´ away

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4- With respect to Master’s Standing Orders enlist what would you write in the following

circumstances;

(a) Factors that relieving OOW should satisfy themselves with when taking over the watch; (6)

(b) Handing over a watch at sea; and (6)

(c) In case of main engine failure. (6)

5- At 0040 hours a 325 meters’ container vessel is proceeding in the general direction of traffic

flow in the SW bound lane (Dover Straits Traffic Separation Scheme) and is steering 240° T at a

speed of 12 knots.

The visibility is estimated to be 1.0 mile and the vessel's engines are on standby and ready for

immediate manoeuvre.

Radar Plot-3 shows a radar plot, on the 6-mile range, obtained by the OOW, over a 10-minute

period, the plot being completed at 0050 hours.

(a) On Radar Plot -3, for targets A, B and C, determine each of the following:

(i) the course and speed; (3)

(ii) the CPA and Time of CPA; and (3)

(iii) the aspect at 0050 hours. (5)

(b) Determine the action that a prudent master would take at 0055 hours to ensure that all targets

pass at least 1.0 mile clear of the vessel. (5)

Note: assume that any alteration of course and/or speed have instantaneous effect.

(c) Explain fully how the action taken in (b) complies with Rule 19 of the International

Regulations for Preventing Collisions at Sea 1972. (4)

6- With respect to navigation in ice;

(a) State the signs which may indicate the proximity of ice on clear days and nights; (4)

(b) Discuss the limitations of radar as a means of detecting ice; and (4)

(c) State the precautions to be taken when navigating near ice, and when ice is suspected in the

vicinity. (4)

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MohammedSha

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RADAR PLOT - 3

MohammedSha

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Scale = 6 Nautical miles

MohammedSha

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MohammedSha

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Sultanate of Oman



Competency written examinations

Chief mate - Stability

Please note the followings;

1 While answering computational questions, all computation steps including formulas, that have led to

the final answer must be shown on the answering sheets to show how the final answer was reached.

2 During computations round up answers for each step to 2 decimal points.

3 In computational questions, for each principle error 50% and for each editorial or mathematical error

25% of the allocated mark for that question or part of question, as the case may be, would be deducted.

4 All answers, with the exception of graphs, sketches and diagrams should be written in black or blue

pen, unless otherwise specified. Answers written in pencil will not be marked.

5 Upon completion of the examination, all rough papers used for pre-calculation or other purposes

should also be attached to the answering sheets and along with question paper handed over to the

invigilator.

6 Any unauthorized materials, such as books, paper, documents, pictures and electronic devices with

communication and/or storage capabilities such as tablet PC and smart watch are not allowed into the

examination room.

7 Mobile phones, if carried shall be switched off. If candidate’s mobile phone is found to be switched

on in the examination hall, the mobile phone will be confiscated and retained for investigation of possible

infringement of the examination discipline.

8 During examination candidates are not allowed to exchange any views verbally or by notes and

should remain silent in order to avoid disturbing other candidates.

9 Any candidate infringing the examination discipline would be asked to leave the examination room,

considered failure in the examination subject and barred from re-examination for a period of maximum 6

months.






Subject: Stability Time allowed: 3 hours


1. (a) State the effect of reducing the KG on:

(i) a vessel at an angle of heel due to an off-center weight; and (2)

(ii) a vessel at an angle of loll. (3)

(b) State the effect of winging out weights on a vessel on:

(i) the critical period when drydocking; and (2)

(ii) the rolling period of the vessel. (3)

(c) State the effect of increasing a vessel's trim by the stern on:

(i) the GM at the critical instant when drydocking; (2)

(ii) the maximum cargo to load with limited underkeel clearance; and (2)

(iii) the vessel's True Mean Draught. (2)

(d) State the effect of an increase in a vessel's displacement on:

(i) the virtual loss of metacentric height due to free surface; and (2)

(ii) an angle of heel due to an off-center weight. (2)

2. (a) Explain why a vessel laden to the same draught on different voyages may have different natural

rolling periods. (5)

(b) Explain the term synchronous rolling, describing the dangers associated with it. (6)

(c) State the actions to be taken by the ship's officer when it becomes apparent that the vessel is

experiencing synchronous rolling. (5)

3. (a) Explain how wind heeling moments are calculated. (7)

(b) Sketch a vessel's curve of statical stability, showing the effects of a strong beam wind. (7)

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4. On arrival at loading port a vessel of displacement 12000 tonnes is upright with KG of 8.31m and

all tanks are pressed up. The following are then loaded symmetrically about the centre line:

Deck cargo 600t at Kg of 11.50m, Ballast 600t at Kg of 0.60m

During the voyage to the discharge port the following are consumed symmetrically about the center

line:-

Bunkers 240t from Kg 0.60m leaving the tank empty,

Fresh water 60t from Kg 5.80m leaving the tank partially full with rectangular surface area of

length 15.0m and breadth 6.00m.

In addition, the deck cargo uniformly absorbs 15% of its own weight of water.

On arrival at the discharge port the hydrostatic particular of the vessel give BM 4.00m and KM

8.23m.

Calculate angle of list to be expected on arrival at the discharge port. (17)

5. A box-shaped vessel floating at an even keel in salt water has the following particulars:

Length 110.00m, Breadth 24.00m, Draught 6.200m, KG 9.58m

An amidships watertight compartment 19.00m long, height 7.00m, and extending full breadth of

vessel, is bilged. The compartment is fully loaded with cargo of relative density 0.82 and stowing at

1.64 M3/tonne.

Calculate EACH of the following:

(a) the final draught; and (8)

(b) the change in GM. (8)

6. (a) Explain why a vessel will heel when turning. (3)

(b) A vessel has the following particulars:

Even keel draught 8.720 m, Maximum breadth 22.60 m, KG 7.96 m, KM 8.38 m, KB 4.18 m

(i) Calculate the angle and direction of heel when turning to port in a circle of diameter 500 m

at a speed of 18.2 knots. (10)

(ii) Calculate the new maximum draught during the turn in (b)(i), assuming the midships cross-

section can be considered rectangular. (4)

Note: assume 1 nautical mile = 1852 m, and g = 9.81 m/s2

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1. A vessel with a high deck cargo of containers will experience adverse effects due to strong beam

winds on lateral windage areas.

Explain, with the aid of a sketch of the Statical stability curve, how the effects of steady and gusting

winds are determined, stating the minimum stability requirements with respect to wind heeling

under the International Code on Intact Stability, 2008 (2008 IS Code). (20)

2. (a) Explain the difference between the Angle of Deck Edge Immersion and the Angle of Flooding,

stating which one occurs first when a ship is heeled. (3)

(b) A vessel in the upright condition has a small negative GM. Explain how, when a vessel heels

to an angle of loll, it now has a small positive GM. (6)

(c) Explain why a vessel carrying timber on deck may be allowed a smaller GM than is usual for

a cargo vessel. (5)

(d) Explain how an increase in the beam of a vessel can improve a vessel's stability and why such

improvement is more pronounced at smaller angles of heel. (5)

3. (a) A ship is shipping heavy seas over one side of the vessel:

(i) explain why this is likely to have detrimental effects on the vessel's transverse stability;

(ii) show the effect on a sketch of the vessel's statical stability diagram. (5)

(b) During a sea passage a vessel develops an angle of loll:

(i) show the effect of an alteration of course involving a significant rate-of-turn on the

vessel's stability diagram; and (4)

(ii) describe how this effect could be minimized (other than improving the GM). (3)

4. A box-shaped vessel 150m long, 10m beam, and 5 m deep, has a mean draft in salt water of 3m

and is trimmed 1m by the stern, KG = 3.5 m.

State whether it is safe to drydock this vessel in this condition or not, and give reasons for your

answer. (15)

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5. A vessel, initially upright, has the particulars: Displacement 13 000 t, KG 7.50m, KM 9.12m

The vessel is to load a 76 tonnes locomotive using the vessel’s heavy lift derrick, the head of

which is 26.75m above the keel. The locomotive is to be lifted from a position 29.30m to port of

the centreline of the vessel.

(a) Calculate the maximum angle of heel. (6)

(b) Show, with the aid of a labelled sketch, the effect on the vessel’s dynamical stability when first

taking the weight on the derrick. (5)

(c) Calculate the weight of ballast water to transfer between a divided double bottom over a

transverse distance of 10.00m so as to limit the maximum list to 5 degrees. (6)

6. A box shaped vessel floating on even keel in dock water of R.D. 1.014 has the following

particulars:

Length 124.00 m, Draught 7.800 m, Breadth 20.00 m, MCTC (salt water) 300.

There is an empty watertight forward end bottom compartment, length 10.00 m, height 6.50 m,

extending the full width of the vessel.

Calculate the draughts forward and aft, if this compartment is bilged. (17)

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1. (a) State the minimum intact stability criteria required by the IMO International Grain Code.

(6)

(b) Describe, with the aid of a sketch of a curve of statical stability, the effect of increasing the

GM on a vessel with a list due to a transverse shift of cargo. (12)

2. (a) Discuss the factors affecting the virtual loss of GM due to a free surface within an undivided

rectangular tank. (4)

(b) Explain the effect on the virtual loss of GM due to the free surface when the slack tank is

equally divided in EACH of the following situations:

(i) by a longitudinal bulkhead; and (3)

(ii) by a transverse bulkhead. (3)

(c) Explain why stability information relating to free surface for a particular tank is usually

expressed as a Free Surface Moment (FSM). (3)

(d) A double bottom tank, initially empty, is to be ballasted full of salt water. Sketch a labelled

diagram to show the way in which the effective KG of the ship will change from the instant

of starting to fill the tank until it is full. (6)

3. (a) Explain why a vessel experiences a virtual loss of metacentric height during drydocking. (6)

(b) Explain why the KM in the freely floating condition, prior to drydocking, should not

normally be used in the calculation of the GM at the critical instant. (4)

(c) Explain why it is usual for a vessel to enter drydock with a stern trim. (2)

(d) Describe the practical measures that can be taken to improve stability prior to drydocking if

it is found to be inadequate. (3)

4. (a) Define dynamical stability. (4)

(b) The righting levers of a vessel displacing 9500t are as follows:

Heel: 0o 10 o 20 o 30 o 40 o

GZ(m): 0 0.04 0.14 0.40 0.55

Calculate each of the following:

(i) the dynamical stability at 40 o; and (10)

(ii) the residual dynamical stability at 40 o if the vessel is subjected to a steady wind

moment of 380tm. (3)

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5. A vessel, initially upright, is to carry out an inclining test.

- Present displacement is 4700 t and KM is 10.63 m

- Total weights on board during the experiment are as follow:

Ballast 368 t, Kg 3.48 m, Tank full;

Bunkers 182 t, Kg 3.91 m, Free surface moment 974 tm;

Fresh Water 86 t, Kg 4.54 m, Slack tank. Free surface moment 799 tm; and

Inclining weights 50 t, Kg 8.88 m.

At the time of the experiment the boilers are empty. They would usually contain a total of 26 t of

water, Kg 4.22 m, with a free surface moment of 129 tm.

A deck crane, weight 21t and still ashore will be fitted on the vessel at a Kg of 9.86 m at a later

date.

The plumbline has an effective vertical length of 7.90 m. The inclining weights are shifted

transversely 7.50 m on each occasion and the mean horizontal deflection of the plumbline is 0.69

m.

Calculate the vessel's Lightship KG. (15)

6. A ship of 10 000 tonnes displacement is listed 5 degrees to port and trimmed 0.2 m by the

head. KM = 7.5 m, KG 6.8 m, and MCTC= 150 tm. Centre of flotation is amidships.

No.1 double bottom tank is divided at the centre line, each side holds 200 tonnes of oil and the

tank is full.

No.4 double bottom tank is similarly divided each side having a capacity of 150 tonnes, but the

tank is empty.

The centre of gravity of No.1 tank is 45 m forward of amidships and the centre of gravity of No.

4 tank is 15 m aft of amidships.

The center of gravity of all tanks is 5 m out from the centre line.

It is desired to bring the ship upright and trimmed 0.3m by the stern by transferring oil.

If the free surface effect on GM be neglected, find what transfer of oil must take place and also

the final distribution of the oil. (16)

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competency written examinations chief mate - navigation

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