384: NICHOLLS S SEAMANSHIP AJNL>
7. What is the weight of a ship's boat and its contents if it displaces
250 cubic feet of fresh water?
Ans.—6-93 tons.
8. In what proportion does the pressure of water increase with
the depth?
9. A flat plate measuring 6 ft. XlO ft. is suspended horizontally at a
depth 0^20 feet, what pressure is exerted on its surface ?
Ans.—76,800 Ibs.
10. Will a ship filled with water sink to the bottom?
11. The sea-cock of a double bottom tank is left open, the waterline
is 10 feet above the top of the tank, the area of which is 1500 square feet.
What is the total upward pressure on the tank top?
Ans.—428-5 tons.
12. How are water ballast tanks tested?
13. Describe the principle of the atmospheric sounding tube in
determining the depth of water.
14. If the volume of air in a tube is reduced to 2 inches on reaching
the bottom, what is the corresponding depth in fathoms?
Ans.—60£ fathoms.
15. Name the Authorities who assign load lines to British ships.
16. Sketch and describe fully the International Load Lines on a
ship's side.
17. What do the following letters mean, LR, BC, BT, S, W,
WNA, T> F?
18. Give the lengths of the various lines and.their breadth, also the
diameter of the disc.
19. What special significance is attached to each of the load lines?
20. What load lines are marked on the sides of sailing vessels?
21. How could you tell on looking at a ship's side whether her
marks were for ordinary cargoes or for timber deck load?
22. To which edge of the load marks is a ship submerged?
23. How could you tell tow much deeper the T S mark may be
submerged when loading in freoh water?
24. What is meant by "Zones" and "Seasonal Areas?"
25. What compulsory marks, other than load lines, are shown on a
snip, and where?