nmit_mri 2302 general ship knowledge_ch 3. hydrostatic and stability_5.reserve buoyancy
TRANSCRIPT
GENERAL SHIP
KNOWLEDGE
- MRI 2303 -
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -2-
RESERVE BUOYANCY
Buoyancy water displaced by underwater volume of a floating vessel
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -3-
RESERVE BUOYANCY
Reserve buoyancy amount of buoyancy (volume of the vessel) above waterline
Freeboard the height above the waterline of the uppermost continuous deck
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -4-
RESERVE BUOYANCY
Reserve buoyancy: Amount of freeboard
Important for vessel’s safe operation at sea
Support vessel in case of bad weather or damage
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -5-
RESERVE BUOYANCY
Volume displacement Volume of the vessel under waterline/submerged
Volume of water displaced by the vessel
V () = Lwl x B x T x Cb [m3]
Displacement weight displacement
Weight of the vessel submerged
Weight of water displaced by the vessel
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -6-
RESERVE BUOYANCY
Displacement Displ () = x ρsea water [ton]
ρsea water = 1025 kg/m3 = 1.025 ton/m3
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -7-
RESERVE BUOYANCY
Ton per centimeter immersion (TPC) Amount of weight which will sink the vessel 1 cm
deeper
Amount of weight which will increase the draft by 1 cm
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -8-
RESERVE BUOYANCY
More load
greater displacement
deeper sink
less reserve buoyancy
less safety
Never overload!!
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -9-
RESERVE BUOYANCY
Lightship and loaded freeboard Less freeboard = less reserve buoyancy
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -10-
RESERVE BUOYANCY
Every vessel has certain particular design Certain freeboard
Sufficient reserve buoyancy
Operation guidance
Safety of vessel and crew
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -11-
RESERVE BUOYANCY
Sufficient freeboard required at all times Prevent vessel being swamped and overwhelmed
Commercial vessels: Assigned by load line (Plimsoll line)
Load line submerged offense
Non watertight structures have no contribution
MRI 2302 GENERAL SHIP KNOWLEDGE
[3] HYDROSTATIC AND STABILITY -12-
RESERVE BUOYANCY
Less reserve buoyancy = LESS SAFETY