Stability & Construction Flashcards
What is meant by an angle of loll?
When the GM = 0 the vessel will sit at an angle of loll which means it will sit at an angle of heel.
What would you do to the quick closing valves before entering a hotter climate?
Open the vent valves to allow for thermal expansion.
How does the free surface effect work?
When fluid moves its COG changes, which in turn causes it to move even more.
If it was to slam this creates a nudging effect which can put the vessels COG of the a side.
What is GZ?
The righting lever a vessel has.
What is a freeing port?
An open hole in the bulwark that allows rapid draining of water from the weather deck, but does not allow water to enter.
What are the conditions of assignment?
The conditions that must be met before the load line can be used on a vessel:
1) Adequate ship strength.
2) Adequate reserve buoyancy.
3) Prevention of entry of water into the hull.
What is a girder?
A longitudinal member used for the bottom of the ship. Centre girder is always one continuous piece and fastened to the keel with a continuous weld.
What is a beam?
Increases load bearing capacity and avoids bending of the structure.
What is framing?
Method used to stiffen the bottom shell and side plating of a ship against compressive forces of the sea. Basically the skeleton.
What is a cofferdam?
An empty space in a ship so compartments on each side have no common boundary. Kept gas tight and properly ventilated.
What is the double bottom and plate floor?
Transfers strength imparted by members running along the ship.
What do panting beams do?
Increase bow resistance to panting and increase bow strength for pounding.
What are bilge keels?
Reduce the rolling amplitude of the vessel:
1) Provide resistance when the ship rolls.
2) Producing lift when the ship is moving.
How do thrust blocks work?
Used to transmit the ahead and astern thrust from the propeller into vessel motion.
Transmitted along the rotating shaft into the stationary thrust block which in turn is strongly connected to the ships hull with hydraulic holding down bolts.
What is the purpose of a panting beam?
To strengthen the bow of the ship.
What is the Rise of Floor?
The rise of the bottom shell plating above the base line.
What is the Parallel Middle Body?
The length of the ship where the midship section remains in constant area and shape.
What is the collision bulkhead?
The foremost watertight transverse bulkhead constructed to mitigate the inflow of water in case of forwarding damage.
What does the ‘A’ class division mean?
1) Constructed of steel or equivalent.
2) Prevent passage of smoke and flame for 1 hour.
3) Suitably stiffened and intact with the main structure of the vessel.
4) Not rise more than 140 or joints 180 in the times.
A60
A30
A15
A0
What does the ‘B’ class division mean?
1) Non-combustible materials.
2) Preventing passage of flame for 30 minutes.
3) Not rise more than 140 or joints 225 in the times.
B15
B0
What is a duct keel?
The duct keel is a plated box/tunnelled keel allowing passage right forward. It provides additional buoyancy, together with a through passageway for cables and pipelines running in the fore and aft direction.
