Re: Auxiliary Repair Docks ARD-2 Class
Auxiliary Repair Docks ARD-2 Class
In 1935 the Bureau of Yards obtained $10,000,000 to design and build a dock based upon ARD-1, but capable of lifting any naval vessel afloat. The dock was to be 1027 feet long, with a beam of 165 feet, and moulded depth of 65 feet. Complete plans and specifications were drawn up and invitations to tender issued. However, bids to build the dock far exceeded the budget, and the project was abandoned. This dock was to be ARD-3, and so this dock was never built.
There is somewhat of a mystery concerning ARD-4. One source refers to the order being cancelled, and another lists it as being completed by Pacific Bridge in May 1942. I can find no other reference to this dock anywhere. However, I have found a photograph purported to be of ARD-4? Hmmm …
But the ARD-2 Class did definitely comprise of eight other docks:
ARD-7 West Milton
These docks were bigger than ARD-1 at 485 feet 8 inches long (usable length 413 feet) and overall width of 71 feet (clear width 49 feet 4 inches), and a depth over the blocks of 21 feet. This gave a nominal lifting capacity of 3500 tons, although I have also seen this stated at 4200 tons.
The bottom pontoon was divided by one longitudinal, and four transverse bulkheads into eight ballast tanks. Each wing wall was divided into five ballast tanks, and, in addition, two tanks were provided in the bow, forward of the head wall of the inner dock. A watertight horizontal safety deck installed in the wing walls and bow precluded immergence below the minimum designed freeboard and helped to prevent undue trim or list at deep draft.
These ballast tanks were interconnected by valved piping to two pumping plants, each consisting of two vertical shaft pumps rated at 15,000 g.p.m. at 12 feet head. The flooding and pumping system permitted submerging the dock to minimum freeboard in 50 minutes, and raising the dock and pumping the basin dry in 100 minutes. The ballast tanks were equipped with water-level indicators centralized in the control house, from which all pump and valve operations were also remotely controlled.
Above the safety deck in the wing walls were two machinery decks. The lower, or C, deck accommodated the pump and valve motors, small machines, welding equipment, and storage spaces. The upper, or B, deck accommodated the main diesel generators and other heavy equipment, as well as quarters and messing facilities for the crew. In the bow, the upper deck was omitted in order to provide adequate headroom for the hull repair shop.
The docks were equipped with four railway-type diesel engines directly connected to electric generators. As originally designed, provision was made in these docks for the installation of low-power electric drive propulsion machinery. However, none of the docks was actually equipped with propulsion, partly because of the urgent need for such equipment for ships and partly because of the infrequent use which could be made of it.
The docks had bottom-hinged stern gates that were appreciably different from the gate used for the ARD-1, being closed by an electrically driven sprocket and roller chain device at either side, and opened by gravity. Operating difficulties with this mechanism led eventually to its replacement with hydraulic gate operating gear similar to that used in the ARD-1 and providing positive force and control for both closing and opening.
There was some light armament in the form of two single 20 mm guns. The docks had a compliment of 6 Officers and 125 crew.
ARD-2 was built by the Pacific Bridge Company in Alameda, California, and was completed in April 1942. It was commissioned as USS ARD-2 in 1943.
No real operational records for the dock other than USS Tracy DD214 entering the dock for hull repairs in July 1945, San Pedro Bay, Gulf of Leyte, Philippine Islands. I think this was the base for Service Squadron Ten. It appears that the dock may previously have been based at Ulithi athol in the Caroline Islands.
On the 19th of May ARD-2 left Ulithi as part of a towing convoy transporting non-self propelled equipment to the new base at San Pedro Bay some 900 miles away. The convoy consisted of 9 towing vessels, each having 2 service vessels, towing 4 hotel barges, 3 concrete floating docks, 3 repair barges, an oil barge, 6 barges of food/stores, and ARD-2. Accompanying the convoy were 4 YTN harbour tugs, 2 refuse barges, 1 petrol barge, 1 oil barge, and 1 degaussing barge. The convoy arrived safely on the 24th of May 1945.
I am not certain about the fate of ARD-2, except there is a reference to the dock being sent to Mexico in 1963, and possibly stil being in use.
ARD_2: The only photograph of ARD_2 I can find. With USS Cubera ((SS347), Key West 1970.This does not support the reference to the dock going to Mexico in 1963? Photogaph accredited to John Hummel.
ARD4_1: This is captioned as ARD-4; unknown place/date. But is it? Navsource Online. From the Stephen Urbani Collection 1935 to 1942.
"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." - Sir Henry Royce