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opening. In either case the small opening in the bulkhead for conveying water to the float from the opposite side is automatically closed when the balance weight falls.

These valves under the conditions on board ship, are found to

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be far from efficient, and require jamming home by hand. All the bearing surfaces should be kept clean (see Admiralty circulars mentioned below).

Inspection of Watertight Doors.—As so many doors have to be left open for access throughout the ship, even supposing an action is proceeding, it is obviously of the highest importance that they should all be in perfect working order, and the crew well exercised in closing them, so that they can be readily closed in any time of emergency. The following extracts from the "Steam Manual" gives the instructions regarding this:—

"The watertight doors and sluice valves are placed under the charge of the Chief Engineer. All the Engineer Officers must make themselves acquainted with the positions and methods of closing of watertight doors. All watertight doors are to be kept clear for immediate closing. No fitting of any kind is to be allowed which will require to be removed before the door is closed. Watertight doors and sluice valves are to be opened and shut regularly once a week to ensure their being in good working order. The Chief Engineer, besides preparing the station bill, is to take such measures as he may deem necessary to ensure that every person under his control shall know his post and be capable of performing his duty, so that in case of emergency the watertight doors and sluices may bo closed without confusion."

Similar instructions are given in the King's Regulations. Recent instructions have been issued in Admiralty circular, S. 32111/1903, of January 29, 1904, in regard to watertight doors and hatches. See also S. 31157/1903, of January 9, 1904, for Admiralty circular referring to H.M.S. Prince George.

Automatic Doors.—The following extract from Sir William White's report * on the loss of the Victoria may be quoted with reference to the suggestion frequently made that automatic or "self-closing" doors should be adopted instead of existing arrangements :—

"This suggestion is a revival of one made long ago, then carefully considered and put aside after certain experimental doors had been tried.

"Automatic arrangements are applied in valves to ventilating trunks and other small openings in bulkheads and platforms. Even in such cases the feeling of the Naval Service has led to the automatic fittings being supplemented by the means of closing the valves when desired. In doors and scuttles the risks of the automatic appliances failing to act, or of solid materials being carried into openings by a rush of water, and preventing doors from closing properly, would be much greater. These considerations have led to the retention of existing fittings, the design of which provides that, when properly closed and secured, doors and hatchway covers shall be as strong as the neighbouring partitions, and watertight under considerable pressure.

"There is no difficulty in making automatic appliances. It is a question of what plan secures the maximum of safety under the working conditions of the Royal Navy. With large numbers of disciplined men, familiar with the fittings, and constantly drilled in their use, it is possible to close and properly secure all the doors, etc., in a battle-ship in three to four minutes, or possibly a less time for ships after long periods in commission.

"In the Victoria, no orders were given to close doors until one minute before collision. It is established by the evidence that the doors, etc., were in good order. The failure to close doors, therefore, was due entirely to the insufficiency of time available, especially in compartments breached by the collision.

"Under these circumstances no new argument in favour of the use of automatic doors seems to arise out of the loss of the Victoria."

* Parliamentary Paper, No. C. 7208/1893.

CHAPTER VII.

STEMS, STERNPOSTS, RUDDERS, AND SHAFT BRACKETS.

Stems.—The simplest form of stem is that formed by a flat bar, to which the plating at the forward end is secured. This form of stem is adopted in merchant vessels and in the smaller classes of ships in the Royal Navy, as third class cruisers and destroyers. For larger war vessels, however, a stronger form of stem is necessary, because it is desirable that such vessels should be able to effectively ram an enemy's ship, without at the same time sustaining serious damage herself. The most effective form of stem

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for this purpose is one having a ram below water, projecting well forward, so that it shall damage the slight under-water portions of the structure well in from the side before being brought up by the strong structure of the armour or protective deck of the other vessel (see Fig. 65).

Stems of steel vessels are now made of cast steel, a material possessing good strength and ductility (see Chapter II.), and capable of being cast into most efficient forms for the special purpose required. These castings are a great advance on the iron forgings formerly in use, and a much more efficient ram has been by this means rendered possible.

When a vessel is sheathed with wood and copper we cannot use cast steel for the stem because of the galvanic action that would in all probability ensue between the copper and the steel. In such ships, therefore, the copper alloy, phosphor bronze, is used, but on account of the low strength of this material, the

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casting has to be much more massive than a corresponding one of cast steel.

In the earlier ships with cast steel stems {Royal Sovereign to Canopus), the stem casting was carried well down into the body of the ship (Fig. 66), and on this account it had to be made in two pieces, because of the difficulties attending the manufacture and transport of such a large and intricate casting. The two pieces were connected together, as shown, by a scarph (Fig. 66), a tapered key being driven in to draw the parts together, and the whole well secured by screw bolts. The scarph was necessarily a place of weakness, and this has been avoided in more recent ships by making the casting all in one piece. In order to do this the lower portion is made much shorter (see Fig. 67). This sketch shows the general shape of the casting, the ship being swelled out in way of the ram. Inside the ram projection two webs are cast, one vertical and one horizontal.

It is most important to support the stem effectively by the

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adjacent structure. The following arrangements are made with this object in view, viz.—

(i.) The outer bottom plating is doubled in thickness and recessed into the casting.

(ii.) The bow protection, in this case 2 in., is recessed into the casting for one half its thickness.

(iii.) The lower deck, which is a thick deck, is well connected to a large projection on the stem casting.

(iv.) At the level of the platform a 2-in. plate is worked, well connected to the horizontal web inside the ram. This 2-in. plate extends back to within 3 ft. of the collision bulkhead.

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