Chapter 13: The Nurse of the Navy

Just as a navy requires floating distilleries, floating coal stores and floating docks, so does it find very important uses for a floating workshop, which can accompany a fleet to sea and execute such repairs as might otherwise entail the return of a ship to port.

The British Navy has a valuable ally of this kind in the torpedo depôt ship Vulcan, which contains so much machinery, in addition to the “auxiliaries” already described, that a short account of this vessel will be interesting.

The Vulcan, known as “The Nurse of the Navy,” was launched in 1889. She measures 350 feet in length, 58 feet in beam, and has a displacement of 6,830 tons. Her bunkers, of which there are twenty-one, hold 1,000 tons of coal, independently of an extra 300 tons which can be stowed in other neighbouring compartments. When fully coaled she can cruise for 7,000 miles at a speed of 10 knots; or travel at first-class cruiser speed for shorter distances.

The most striking objects on the Vulcan are two huge hydraulic cranes, placed almost amidships abreast of one another. They have a total height of 65 feet, and “overhang” 35 feet, so as to be able to lift boats when the torpedo-nets are out and the sides of the vessel cannot be approached. The feet of the cranes sink 30 feet through the ship to secure rigidity, and the upper deck, which bears most of the strain, is strongly reinforced. Inside the pillar of each crane is the lifting machinery, an hydraulic ram 17-1/2 inches in diameter and of 10-foot stroke. By means of fourfold pulleys the lift is increased to 40 feet. When working under the full pressure of 1,000 lbs. to the square inch, the cranes have a hoisting power of twenty tons. In addition to the main ram there is a much smaller one, the function of which is to keep the “slings” (or cables by which the boat is hoisted) taut after a boat has been hooked until the actual moment of lifting comes. But for this arrangement there would be a danger of the slings slackening as the boat rises and falls in a seaway. The small ram controls the larger, and the latter cannot come into action until its auxiliary has tightened up the slings, so that no dangerous jerk can occur when the hoisting begins.

The cranes are revolved by two sets of hydraulic rams, which operate chains passing round drums at the feet of the cranes, and turn them through three-quarters of a circle.

On the Vulcan’s deck lie six torpedo boats and three despatch boats. The former are 60 feet long, and can attain a speed of 16 knots an hour. When an enemy is sighted these would be sent off to worry the hostile vessels with their deadly torpedoes, and on their return would be quickly picked up and restored to their berths, ready for further use.