2. Heel to the wounded (starboard) side.

1. Depression of the bow.-About four minutes after the collision the bow had sunk enough to bring the stem-head under water The forward part of the deck then became submerged, allowing water to pass down the scuttle on the upper deck and then down the turret ports, the water level reaching to the sill of the door in the battery front starboard, and the bottom of the foremost gun-port. At this moment the stem-head was depressed about 23 ft. from its normal position.

2. Heel to starboard.-Accompanying this depression by the bow, a gradual heel to starboard took place, until a heel of about 20° was reached. At this time the door in the battery front and the foremost 6-in. gun-port were just awash.

Both the above movements were accelerated by the motion ahead of the Victoria, the ship being made to steam slowly towards the land with the helm hard-a-starboard.

At this time, at the heel of 20°, a sudden lurch to starboard took place, and the vessel capsized and went down head first.

Calculations have been made, using for data the observed conditions, to investigate the cause of the sudden lurch that was observed; the suddenness of this lurch was without doubt the cause of the great loss of life.

The loss of buoyancy caused by the opening up of the compartments forward, which were inevitably flooded by the collision, and those flooded subsequently through open doors and hatchways, caused a change of trim of 29 ft., or 23 ft. depression forward and 6 ft. lift of the stern. Taking the ship in this condition, but supposing the turret ports, battery doors, and gun-ports closed, the vessel would have a positive metacentric height of 18 ft. In Fig. 208 the shape of the intact waterplane is shown by I, and the shape of the waterplane area under the above condition is shown by II. In Chapter XVI. it is seen that the distance between the centre of buoyancy and the transverse metacentre is directly proportional to the transverse moment of inertia of the waterplane at which the ship is floating BM =

(BM

I

Under the conditions

assumed above, the waterplane area would have a transverse moment of inertia of 3,888,000, giving such a position of the transverse metacentre that a metacentric height of ft. was retained. The ship under this assumed condition was in a condition of stable equilibrium.

Taking now the actual state of the ship with the turret ports, the battery doors, and the gun-ports open, the waterplane would be suddenly reduced to the shape shown by III in Fig. 208. This area only has a transverse moment of inertia of 2,783,000, lowering the transverse metacentre and bringing it below the C.G. This gave the ship a negative metacentric height of 1.8 ft., which rendered the ship unstable, and so she capsized.

The fore-and-aft distribution of the waterplane area, shown in Fig. 208, made a great reduction in the fore-and-aft moment of inertia of the waterplane, and this considerably decreased the "moment to change trim 1 in.," rendering the ship less and less able to resist change of trim as the water gained access to the forward compartments.

The following conclusions were reached as the result of the inquiry into the circumstances of the Victoria's loss:

1. So far as can be judged, had all doors, hatchways, etc., been closed prior to the collision, the Victoria would have continued to retain ample buoyancy and stability, and would not have ceased to be under control.

2. Even when so seriously injured and brought to such a critical condition, as was the case, had the turret ports and upper deck battery been closed, the armour door secured, and water excluded from the turret and battery, the Victoria would not have capsized. It is possible that she may have eventually foundered in consequence of the gradual passage of water into the forward compartments.

3. That under the serious circumstances of this collision, or of any similar accident which may occur, the safety of a ship and her continued flotation, demand that provision should be made for closing gun-ports and openings in upper works, through which water may pass into the interior of the ship, if the flooding of

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

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 most recent method of protection of large cruisers is more likely to prove 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.