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the compartments produces great change of trim or serious, heeling.

If such precautions are not taken, the virtual height of freeboard is reduced to the height of sills or doors, and the presence of the superstructures, when water is not excluded from them does not assist either buoyancy or stability to any sensible extent.

For a detailed account of the above, see

(i.) "Ironclads in Action." H. W. Wilson.

(ii.) "Life of Admiral Tryon." Admiral Fitzgerald. (iii) Brassey's Naval Annual, 1894.

(iv.) Parliamentary Paper, No. C. 7208, of 1893.

(v.) Engineer, November 10, 1893.

APPENDIX A

QUESTIONS.

CHAPTER I.

1. Distinguish between the terms "structural" and "local" strains as applied to a ship. Enumerate a number of “local” strains. Have any of these local strains been sufficiently great in your experience to cause damage?

2. State the reasons for the superior efficiency of a I beam of steel to a solid rectangular beam of wood.

3. How may a ship be compared to a beam, and what parts of the structure are most efficient from this point of view?

4. How are the longitudinal strains on a ship's structure made the subject of calculation?

5. Why is the structure at the keel and at the upper deck considerably stronger in a long cruiser than in a battle-ship of the same total displacement?

6. Why is it that the boat deck and the topside plating adjacent are not made an integral part of the structure in a ship having a boat deck?

7. To what special sort of strain are the flat portions of a ship forward specially liable? Why do you consider that this straining action is less in evidence in war-ships than in merchant steamers ?

8. Why is it possible to build a steel or iron ship considerably lighter than a ship of the same size built of wood?

9. Why must special attention be devoted to the strength of the upper deck and structure adjacent in a vessel of large proportion of length to depth? From this point of view, show that the method of protection of large cruisers as Fig. 138, is likely to prove more economical as regards weight of hull structure than that adopted in, say, the cruisers of the Edgar class.

10. Suppose one had a vessel 300 ft. long, the structure of which had proved sufficiently strong, and a vessel of the same depth, but 360 ft. long were required. Discuss generally what portions of the structure would have to be strengthened to ensure the new vessel being sufficiently strong.

11. Indicate how the inspection and maintenance of a ship influences the design of the structure.

CHAPTER II.

1. State the qualities of "mild steel" that make it a suitable material for shipbuilding purposes.

2. Compare in tabular form the tests laid down for "mild steel,” “rivet ""cast steel.”

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3. What tests are necessary in a steel casting beside those relating to the strength and ductility of the material? Why are such tests of great importance for castings of steel?

4. Compare the tests for “mild steel" and those for the special steel used in cruisers and destroyers.

5. It is laid down that holes in high-tensile steel must be drilled, and not punched. Why is this?

6. Describe the process of "pickling" steel plates. What trouble would you expect to arise in a ship's structure from the steel of which the "mill scale" had not been removed before painting?

7. Draw out to a large scale the section of a zed bar, a tee bulb, an angle bulb, and a I bar. State places in your present ship in which these sections are used.

8. A flange is frequently used on the edge of a plate instead of an angle bar for connection purposes. What advantage is thereby secured? State places in your present ship where this is done.

9. Describe the most ordinary form of rivet used in ship work, and show how such a rivet is used for the outer bottom plating where the outside surface must be flush.

10. What is meant by the pitch of rivets? State the amount of this pitch for rivets 3-in. diameter where the work has to be watertight. What pitch would be used for 3-in. rivets for internal work not watertight?

Ans. 4 to 4 in.; 5 to 6 in.

11. When your ship is next in dry dock, examine the "lap" caulking and the "butt" caulking of the outer bottom plating.

12. State the various advantages that result from ordering plating by the weight required per square foot rather than by thickness.

13. Taking the area of the outer bottom plating of a vessel as 30,000 square ft., estimate the saving of weight, if the steel plating is ordered 20 lbs. per square ft. instead of in. thick. What further saving would

be possible if the manufacturer sends in all the plating down to the limit allowed, viz. 5 per cent. under? Ans. 54 tons; 13.4 tons.

14. If the area of the outer bottom plating (specified of 15 lbs.) is 20,000 square ft., what variation of weight is possible, in view of the latitude allowed to the manufacturer ? Ans. About 13 tons.

15. What is annealing? What is the effect of annealing on a plate which has had a large number of holes punched in it?

CHAPTER III.

1. Distinguish between "bracket frame" and "solid plate frame." Where are these frames used in a large armoured ship?

2. Describe generally the construction adopted in battle-ships below armour within the limits of the double bottom.

66

3. What is a floor-plate"? Sketch and describe the framing of a battle-ship before and abaft the double bottom.

4. State the advantages of having a double bottom to a ship. Why is it not possible to provide a double bottom in the smaller ships of the Royal Navy? Discuss the question of fitting a wing bulkhead below the armour deck in a large cruiser.

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5. Why is the "transverse system of construction more suited to the ends of a large ship than the "longitudinal" system?

6. Draw out a table with rough sketches showing the supporting frames for 4-in., 6-in., 9-in. armour. Why is a rigid support of great importance behind armour ?

7. Draw in outline midship section, describe and compare the main features of (1) Admiral class, (2) Royal Sovereign, (3) Majestic, (4) King Edward VII.

8. Draw in outline midship section, describe and compare the main features of the first class cruisers (1) Edgar, (2) Diadem, (3) Cressy, (4) Monmouth.

9. Draw in outline midship section, and compare the main features of two second class cruisers. Show how the intended service has had a distinct influence on the design.

10. Draw in outline the midship section of a sloop," and point out what provision is made in such a vessel for protective purposes.

11. State in general terms the distinction between a battle-ship and a first class cruiser. Compare H.M.S. Triumph with H.M.S. Duncan and H.M.S. Cressy, and state in what category you consider she should be placed.

12. Discuss the question of working zed bars for the framing of ships instead of two angles riveted back to back from the point of view of (i.) economy of weight, (ii.) saving of cost.

13. Discuss the importance of avoiding discontinuity of strength in a ship's structure.

14. Name typical vessels of the Royal Navy which are sheathed with wood and copper. Why have all the sloops and most of the second class cruisers built in recent years been sheathed?

15. In going through the double bottom of a vessel it will be noticed that the non-watertight longitudinals have no lightening holes in certain frame spaces. Trace the reasons for this.

16. Taking the length of the double bottom of a battle-ship as 250 ft., and the frame spacing 4 ft., make an estimate of the saving of weight if an oval manhole 23 in. x 15 in. is cut in every frame space in the non-watertight longitudinals. Ans. 5 to 6 tons.

17. What advantages beside saving of weight are obtained by cutting lightening holes in a longitudinal girder?

18. State places in your present ship where you have noticed holes cut for lightening purposes. Do you consider any weakness has resulted from the removal of this material?

19. What is a middle-line keelson? When this is intercostal, and the floor

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