Stability & Construction

Question 1

What is meant by an angle of loll?

Answer 1

When the GM = 0 the vessel will sit at an angle of loll which means it will sit at an angle of heel.

Question 2

What would you do to the quick closing valves before entering a hotter climate?

Answer 2

Open the vent valves to allow for thermal expansion.

Question 3

How does the free surface effect work?

Answer 3

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.

Question 4

What is GZ?

Answer 4

The righting lever a vessel has.

Question 5

What is a freeing port?

Answer 5

An open hole in the bulwark that allows rapid draining of water from the weather deck, but does not allow water to enter.

Question 6

What are the conditions of assignment?

Answer 6

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.

Question 7

What is a girder?

Answer 7

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.

Question 8

What is a beam?

Answer 8

Increases load bearing capacity and avoids bending of the structure.

Question 9

What is framing?

Answer 9

Method used to stiffen the bottom shell and side plating of a ship against compressive forces of the sea. Basically the skeleton.

Question 10

What is a cofferdam?

Answer 10

An empty space in a ship so compartments on each side have no common boundary. Kept gas tight and properly ventilated.

Question 11

What is the double bottom and plate floor?

Answer 11

Transfers strength imparted by members running along the ship.

Question 12

What do panting beams do?

Answer 12

Increase bow resistance to panting and increase bow strength for pounding.

Question 13

What are bilge keels?

Answer 13

Reduce the rolling amplitude of the vessel:
1) Provide resistance when the ship rolls.
2) Producing lift when the ship is moving.

Question 14

How do thrust blocks work?

Answer 14

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.

Question 15

What is the purpose of a panting beam?

Answer 15

To strengthen the bow of the ship.

Question 16

What is the Rise of Floor?

Answer 16

The rise of the bottom shell plating above the base line.

Question 17

What is the Parallel Middle Body?

Answer 17

The length of the ship where the midship section remains in constant area and shape.

Question 18

What is the collision bulkhead?

Answer 18

The foremost watertight transverse bulkhead constructed to mitigate the inflow of water in case of forwarding damage.

Question 19

What does the ‘A’ class division mean?

Answer 19

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

Question 20

What does the ‘B’ class division mean?

Answer 20

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

Question 21

What is a duct keel?

Answer 21

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.