1. Floatability of a ship: the ability of a ship to float in a certain horizontal position under certain loading conditions.

2. Ship stability: When a ship is moored or sailing in the water, it will often be inclined by various external forces. When the external forces are eliminated, the ship can automatically return to its original equilibrium position.

3. Sinking resistance of the ship: the ship can still maintain the ability of unsinkability and capsizing after being damaged and flooded, or the ship can still maintain certain unsinkability and stability after being damaged and flooded in the cabin.

4. Seakeeping (swaying) of the ship: when the ship is subjected to various swaying movements, flapping on the waves, stalling and wave bending moments caused by external force interference in the wind and waves, it still has sufficient stability and hull structural strength, and can maintain the performance of safe navigation at a certain speed.

5. Ship rapidity: refers to the ability of a ship to sail at a faster speed at a certain main engine power or at a lower main engine power at a certain speed.

6. Ship maneuverability: refers to the performance of a ship to maintain or change its motion state (ship speed, course and position) under the hydrodynamic action generated by the relative motion of the hull, propeller and rudder with water.

7. Freeboard: f, the vertical distance from the design waterline to the upper edge of the deck at the captain's midpoint.

8. Draft: During the operation of the ship, it is often necessary to know the actual draft and its changes. For this reason, the draft is planned on the hull plates at the front and rear sides of the ship, which is called a draft gauge.

9. Load line: In order to ensure the safe navigation of ships in various conditions and make full use of the load capacity of ships, it is necessary to specify the freeboard dimensions of various ships in different navigation areas, flight segments and different wind and waves according to different conditions.