"Immediately after the disaster of the night of February 8th," when the Japanese, in a surprise attack, torpedoed several of the Russian ships, "the cruiser Pallada was floated into drydock, and the battleships Czarevitch and Retvizan were taken into the inner harbour, and repairs executed by means of caissons of timber, built around the gaping holes which had been blown into their hulls by torpedoes. The repairs to the Pallada were completed early in April, and about the 20th of June the Czarevitch and Retvizan were also in condition to take the sea. On the 13th of April, during the sortie in which the Petropavlovsk was sunk with Admiral Makaroff on board, the battleship Pobieda, in returning to the harbour, struck a contact mine, and was heavily damaged. Similar repairs were executed, and this ship was able to take her station in the line in the great sortie of August 10.
"On June 23 Captain von Essen's ship, the Sevastopol, was sent outside the harbour to drive off several Japanese cruisers that were shelling the line of fortifications to the east of Port Arthur. This she accomplished; but in returning she struck a Japanese mine, which blew in about 400 square feet on the starboard side, abaft the foremast, at a depth of about 7 feet below the water-line. The rent was from 7 to 10 feet in depth and 35 to 40 feet in length. The frames, ten in all, were bent inward, or torn entirely apart, and the plating was blown bodily into the ship. She was taken into the inner harbour, where the injured portion of the hull was enclosed by a timber caisson in the manner shown in the engravings on page [155]. The caisson—a rectangular, three-sided chamber—was built of 9-in. by 9-in. timbers, tongued and grooved and carefully dovetailed. The floor of the caisson abutted against the bilge keel. The outer wall, which was at a distance of about 10 feet from the hull, had a total depth of about 34 feet, the total length of the caisson being about 75 feet. Knee-bracing of heavy timbers was worked in between the floor and the walls, and the construction was stiffened by heavy, diagonal bolts, which passed through from floor to outside wall, as shown in the drawing. Watertight contact between the edge of the caisson and the hull of the ship was secured by the use of hemp packing covered with canvas. The whole of the outside of the caisson was covered with canvas, and upon this was laid a heavy coating of hot tar. The caisson was then floated into position and drawn up snugly against the side of the ship by means of cables, some of which passed underneath the ship and were drawn tight on the port side, while others were attached to the top edge of the caisson and led across to steam winches on deck. After the water had been pumped out, the hydraulic pressure served to hold the caisson snugly against the hull. The damaged plating and broken frames were then cut away; new frames were built into the ship, the plating was riveted on, and the vessel was restored to first-class condition without entering drydock.
The battleship Sevastopol was twice struck by a mine; but she remained afloat and was repaired by the use of caissons without entering dry dock.
Safety Lies in Subdivision
"On September the 20th, during operations outside the harbour, the Sevastopol again struck a mine, and by a curious coincidence she was damaged in the exact spot where she received her first injury. This time, however, the mine was much larger and it was estimated to have contained fully 400 pounds of high explosive. The shock was terrific and the area of the injury was fully 700 square feet. The ship immediately took a heavy list to starboard, which was corrected by admitting water to compartments on the port side. She was brought back into the harbour, and a repair caisson was again applied. The repairing of this damage was, of course, a longer job. Moreover, it was done at a time when the Japanese 11-inch mortar batteries were getting the range and making frequent hits. One 11-inch shell struck the bridge just above the caisson and, when it burst, a shower of heavy fragments tore through the outer wall of the caisson, letting in the water and necessitating extensive repairs. Nevertheless, the Sevastopol was again put in seaworthy condition, this time the repairs taking about two and one-half months' time. During the eleven months of the siege of Port Arthur five big repair jobs of the magnitude above described were completed, and over one dozen perforations of the hull below water, due to heavy projectiles, were repaired, either in drydock or by the caisson method."
Now, when it is remembered that the Sevastopol was not a new ship, and that her internal subdivision was not nearly so complete as that which is found in the most modern battleships, it will be realised how effective are properly built bulkheads and thoroughly watertight compartments against even the most extensive injury to the outer shell of a ship. It is claimed for the latest battleships of the dreadnought type, built for the United States Navy, that they would remain afloat, even after having been struck by three or four torpedoes.
Now, it is inexpedient to build merchant ships with such an elaborate system of watertight compartments as that described in this chapter. Considerations of cost and convenience of operation render this impossible; but it is entirely possible to incorporate in the large passenger steamers a sufficient degree of protection of this character to render them proof against sinking by the accidents of collision, whether with another ship, a derelict, or even with the dreaded iceberg. The manner in which the problem has been worked out in several of the most noted passenger steamers of the present day is reserved for discussion in the following chapter.