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1) What kinds of stability has a ship?
A ship has two kinds of stability, longitudinal and transverse.
2) Which of them is more important?
The transverse stability is more important than the longitudinal stability.
3) What is the tendency of the longitudinal and what of the transverse stability?
The longitudinal stability tends to keep a ship from rolling end over end. The transverse stability tends to keep the ship from capsizing.
4) What is the name of the force that keeps the ship on an even keel?
Its name is the force of buoyancy.
5) To what is the sum of the vertical components of the hydrostatic pressure equal?
The sum of the vertical components of the hydrostatic pressure is equal to the weight of the water displaced by the underwater body.
6) What force keeps the ship afloat?
The force of buoyancy keeps the ship afloat.
7) In which cases is the force of buoyancy reduced?
It is reduced if too much weight is introduced into the underwater body or on one side of the centerline as well as if the ship is stranded and the force of buoyancy is reduced by the reduction of the hydrostatic pressure acting on the underwater body.
8) Give the names of the static forces acting upon the ship hull.
They are the force of buoyancy and the weights on the ship.
9) Give the names of the dynamic forces acting upon the ship hull.
They are the force of wind and waves.
10) The characteristics of a force are its magnitude, line of action and sense. Which of these factors makes the force a vector quantity? Give some examples of scalar quantities.
A force is a vector quantity because besides its magnitude it has a line of action and a sense. Scalar quantities are: mass, time, numbers, etc.
11) What is the center of gravity of a ship?
The center of gravity of a ship is the point where the sum of the moments of all the weights of the ship with reference to any axis through this point is equal to zero.
12) In what plane does the center of gravity lie?
It lies in the longitudinal vertical centerline plane.
13) Where does the center of pressure of the force of buoyancy lie?
It lies at the center of gravity of the volume of displacement.
14) Suppose that the ship is on an even keel, i.e. the centerline plane is perpendicular to the surface of the water. In which plane does the center of buoyancy lie in that case?
It lies in the vertical longitudinal centerline plane.
15) Does the center of buoyancy remain in the same plane when the ship lists or rolls?
No, it doesn't.
16) How is the angle of inclination of a ship designated?
It is designated by the Greek letter phi.
17) How is the point M, the metacenter of the ship, obtained when the ship is inclined?
It is obtained by drawing a vertical line from B1 which cuts the vertical plane of the centerline.
18. Which distance is the metacentric height of the ship?
It is the distance between the center of gravity and the metacenter of the ship.
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