A somewhat similar dock to that at Bermuda, slightly shorter but of greater lifting power, was designed for the Navy Department of the United States of America, and constructed by the Maryland Steel Company at Baltimore, and stationed at Algiers near New Orleans. Its length is 525 feet over blocks, its entrance 100 feet, and its lifting power up to pontoon-deck level no less than 18,000 tons, making it as regards lifting power then the most powerful dock in the world. This lifting could be increased to 20,000 tons by using the “pound.” Its hull weight is 5850 tons.
Self-docking of the Bermuda Dock (well heeled).
Bermuda Dock: Centre Pontoon Self-docked
It is interesting to note the different methods adopted by the Governments of the two countries for the shoring or berthing of the ships on the dock. The English custom in the case of ironclads of the pre-Dreadnought era, and also that of Italy and Japan, is to support the armour belt on more or less vertical shores inserted under an angle-iron firmly attached to the belt.
These shores are put into position as the ship is rising, and, as the water recedes, more and more shores are inserted. The Bermuda dock has large and heavy altars constructed for this purpose. The American custom is to strengthen the bilges of their ironclads with strong bilge docking keels, forming, with the keel proper, a level bottom. No shores are required beyond those necessary to centre the vessel, and no great care is required in adjusting the berth, and one set of bilge blocks does for all sizes of vessels. The American plan affords a great saving in weight and quantity of shores, and, what is more important, a great saving in time, not only in the preparation of the berth and centreing of the ship, but also in the actual lifting. With the American plan it would be perfectly feasible to dock a vessel completely in the time required to centre and adjust her with shores disposed according to English practice.
The Penarth Floating Dock was constructed in 1909 at Wallsend to the order of the Penarth Ship Building and Ship Repairing Company, Ltd. The dock is of the off-shore or single-walled type, and is one of the finest of its kind. It has an over-all length of about 380 feet, an extreme width of 75 feet, and is capable of accommodating vessels having a beam of 55 feet, with a draught of water up to 18 feet, and a displacement of 4200 tons. Its pumping machinery consists of four centrifugal pumps and engines, for which steam is supplied by two large Babcock and Wilcox boilers, working at 160 lb. pressure. This plant can lift a vessel of 7000 tons dead weight in three-quarters of an hour. For self-docking, the dock is divided transversely into two equal portions, each with its own pumping plant, so that either section can be docked by the other portion. A powerful steam capstan is fitted at each end of the top wall to assist in warping vessels into position when lifting or otherwise. It has eight mechanical side shores in addition to the usual accessories for facilitating the rapid handling of vessels, such as bilge shores, roller fenders, rubbing timbers, and bollards. A duplex reciprocating pump, with a capacity of about 100 tons per hour, has a connection to the main drain of the dock, and enables practically the whole of the water to be pumped out of the dock. On the delivery side the pump is connected to a service-pipe, which has connections at intervals for 3-inch delivery hose. The pump is capable of throwing three jets of water to a height of 40 feet.
To enable this floating dock to enter the wet dock in which it was to work, the entrance to which is several feet less than the width of the dock, a joint was provided running the whole length of the pontoon. On arrival of the dock in Penarth roads this joint was disconnected, and the separate sections towed into the wet dock, and reconnected, and the necessary attachment made to the quay wall.
