Lesson 2 Ship Knowledge Flashcards
- Propulsion cones from which three sources?
- In board engines
- Outboard engines
- Wind
- What is a monohull?
Any vessel with only one hull
- What is a catamaran?
A vessel with two hulls
- What is a multihull?
A vessel with two or more hulls.
What is a trimaran?
A vessel with three hulls
What is the purpose of a cathedral hull?
A cathedral hull, or stabilised monohull, is designed to provide greater initial stability. The vessel is less inclined to lust due to greater buoyancy outboard of the centreline.
- What is a wave piercer?
A catamaran vessel with a central hull clear of the water. The outboard hulls are designed to go through rather than over waves.
What is ‘deadrise’ ?
The angle of the bottom of a vessel compared to the horizontal plane. It is measured from midships.
- What does the deadrise influence?
The angle of deadrise has a great influence on the handling and weakening attributes of a vessel.
- What is buoyancy?
The upward force on a vessel derived from the displacement of a weight of water equal to the weight of the vessel ( produced by watertight volume below the water line)
- What is freeboard?
The vertical distance from the lowest point of the main deck ( usually near midships ) to the water line.
- What is reserve buoyancy?
The watertight volume of a ship above the waterline to the uppermost continuous deck.
- As a fish catch is added to the hold, what will happen to the freeboard and draft?
Freeboard will reduce and draft will increase.
- What is stability?
The ability of a ship to remain upright.
- List two things that impact a ships stability.
1) the vessel design
2) the distribution of weight onboard
- The stability of a ship is mainly determined by the distance between which two points?
1) centre of gravity
2) centre of buoyancy
- What is a ships ‘centre of gravity’?
The point of the ship where the weight of the whole ship and everything in it is said to act vertically downward due to the force of gravity.
- What is a ships ‘ centre of buoyancy’?
The point at the centre of the ship’s underwater volume where the force due to buoyancy is said to act vertically upward.
- Why is overloading dangerous?
It makes it easier to capsize the vessel.
The more weight in the vessel, the lower the freeboard. Overloading compromises the safety of everyone onboard and increases the chances of swamping and capsize.
- What is a ‘tender’ vessel ?
A tender vessel is one with a slower roll period. It is less stable because the centre of gravity has a greater distance from the centre of buoyancy.
- Which vessel is more stable, a ‘ tender’ vessel or a ‘ stiff’ vessel?
A ‘stiff’ vessel.
- Which vessel has the faster roll period, a ‘tender’ vessel or a ‘stiff’ vessel?
A stiff vessel
- What is a ‘stiff’ vessel?
A vessel in which the centre of gravity and centre of buoyancy are relatively close together resulting in a faster roll period.
