nmit_mri 2302 general ship knowledge_ch 3. hydrostatic and stability_1.basic principles
TRANSCRIPT
GENERAL SHIP
KNOWLEDGE
- MRI 2303 -
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -2-
BASIC PRINCIPLES
Hydrostatic: ability to remain afloat while at rest in water
Stability: ability to restore to upright position Inclined by sea (wind/wave)
Of loading condition
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -3-
BASIC PRINCIPLES
Hydrostatic “When a body is wholly or partially immersed in
a fluid, it appears to suffer a loss in mass equal to the mass of the fluid it displaces”
[Archimedes Principle]
“A floating body displaces its own weight in water”
[Law of Floatation]
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -4-
BASIC PRINCIPLES
Buoyant force ≈ weight of water displaces Forces of gravity : G = mship g =Wship
Forces of buoyancy : B = rwater Vdisplaced
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -5-
BASIC PRINCIPLES
Gross tonnage [GT] GT = f(volume of all ship's enclosed spaces)
= K V
V = total ship volume (m3)
K = 0.22 - 0.32
= 0.2 + 0.02 log V
Determining manning, safety and other statutory requirements
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -6-
BASIC PRINCIPLES
Net tonnage [NT] NT = f(moulded volume of all ships’ cargo
spaces)
Indicates vessels’ earning space
Ships’ fees and rules are based on GT and NT
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -7-
BASIC PRINCIPLES
Lightship/lightweight Actual ships’ weight
Weight of hull, superstructure, accommodation and machinery
No fuel, passengers, cargo, water, etc. on board
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -8-
BASIC PRINCIPLES
Deadweight tonnage [DWT] Difference between full load and lightship
Includes but not limited to:
• Fuel
• Provision
• Fresh water
• Crew
• Cargo
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -9-
BASIC PRINCIPLES
Lightship and loaded freeboard
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -10-
BASIC PRINCIPLES
Loadlines/Plimsoll line “A mark on a vessel’s side indicating the
maximum depth to which it may be safely immersed when loaded with cargo”
A requirement by law
• Merchant vessel
• >24m length vessel
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -11-
BASIC PRINCIPLES
Loadlines Laws regulation
The amount of cargo a vessel can carry should still maintain:
• Enough reserve buoyancy
• A low enough center of gravity
Ascertain safety in adverse weather and dangerous seas
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -12-
BASIC PRINCIPLES
Loadlines Dependable variable
• Waters of operation
• Time of year
• Type of cargo
# Timber will have a special depth
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -13-
BASIC PRINCIPLES
Loadline No rising water level above line markers
• Surcharging of cargo
• Any technological fault
Violation of an international shipping act
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -14-
BASIC PRINCIPLES
Loadlines
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -15-
BASIC PRINCIPLES
A typical loadline
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -16-
BASIC PRINCIPLES
A timber to typical load line
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -17-
BASIC PRINCIPLES
Seasonal zone loadline Winter zone
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -18-
BASIC PRINCIPLES
Fresh water allowance [FWA] Difference between fresh water and sea water
draft
Measured as the distance between the top of the Summer (S) line and the top of the Fresh (F) line
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -19-
BASIC PRINCIPLES
Loading a vessel The appropriate loadline must not be submerged
Summer zone water line:
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -20-
BASIC PRINCIPLES
Loading a vessel River/freshwater water line: