US Navy Floating Dry Docks
Now and again, queries appear on the forum regarding US Navy floating dry docks, and not wanting to skew the threads these appear in, and also not wanting to take the established Admiralty Floating Docks thread off track, I thought it be approraite to start a new “sister” thread looking at this topic.
The first U.S. Navy floating dock appears to be a wooden one, used for the West Coast Dock at the Mare Island Naval Yard, Mare Island, California, in 1854. Interestingly, it was the only Navy yard for the Pacific Squadron and, in fact, the only repair facility on the entire PacificCoast. Other docks were apparently built at other yards, but little seems to be known of their history.
After the Spanish-American War in 1898, the U.S. Navy needed a dry dock in the western Pacific. In 1905, USS Dewey (YFD 1) was towed across the Atlantic and Mediterranean, through the Suez Canal, and across the Indian Ocean, arriving at Olongapo, Philippines, 6Ĺ months later. This dock will be covered in due course.
Dewey was built at Maryland Steel (Bethlehem Steel from 1918), Sparrow’s point Maryland, and another early dock, YFD2 was also built there, seemingly, before Dewey in 1900. Her history, and demise at Pearl Harbor, will be featured in a future post. I have found a record that Maryland Steel built a dock for the U.S. navy for service at Algiers on the Mississippi, near New Orleans. This was a four-section self-docking Clark Stansfield design at 525 feet long, and with a lifting capacity of 18,000 tons. The contract to build this dock was awarded in 1899 at a cost of $810,000. I have yet to ascertain whether this was in fact YFD2 (which apparently ended up in the Dominican Republic).
In late 1918, the Morse Dry Dock company began work on a new sectional floating dry dock. Constructed from at least three million feet of timber, and said to be a far more complex and difficult task than the building of a ship, the $1,000,000 dock was six years in the planning and took more than twelve months to build. It was constructed section by section at an ancillary yard of the company at the foot of 63rd St., Brooklyn. By March 1919, the first three sections were ready and were put to use for the first time in lifting the steamer Black Arrow out of the water, at the rate of one foot per minute.
When completed in late 1919, the six-section dock was the largest floating dry dock in the world, capable of lifting a ship 725 feet long and weighing 30,000 tons. In February 1920, all six sections of the dock were used to lift a single ship for the first time, the 30,000-ton SS Minnesota, a task that took 25 minutes.
Evidence of other docks for the U.S. Navy prior to WW2 appears a bit sketchy, and so far I can only find records of one more in service during this time, and this was the 2200 ton ARD1, which is recorded as being in active service in 1934, and taken to Pear lHarbor. Further investigation to be carried out.
In 1935, the Bureau of Yards & Docks obtained $10,000,000 for a similar one-piece mobile dock, to be capable of lifting any naval vessel afloat. Complete plans and specifications were prepared by the Bureau for this dock, which was to be 1,027 feet long, 165 feet beam, and 75 feet moulded depth. Bids received for this huge drydock, designed as ARD3, appreciably exceeded the appropriation, and the project was abandoned when the additional funds needed for its execution were refused. At the same time, plans were prepared for ARD2, an improved and enlarged model of ARD1. But it was not until November 1940, however, that funds were obtained for its construction, and the project placed under contract. More on that later.
Dry docks were generally classifed as follows (note – records of classifications vary):
ABSD - Advance Base Sectional Dock
All Steel Construction. Either ten sections of 10,000 tons lifting capacity each, or seven sections of 8,000 tons lifting capacity. For battleships, carriers, cruisers, and large auxiliaries. (Some records shown smaller capacities of 3,850 tons).
ARD - Auxiliary Repair Dock. (including ARDB and ARDM)
Steel construction with distinctive enclosed ship shaped bow. Normal lifting capacity of 3,500 tons. For destroyers, submarines, and small auxiliaries.
ARDC - Auxiliary Repair Dock, Concrete
Concrete dock with faired bow and stern. 2,800 tons lifting capacity. (Some records 8,300 tons?)
AFD - Auxiliary Floating Dock
Steel dock with faired bow and stern. 1,000 tons lifting capacity. AFDB 3,850 tons.
AFDL - Auxiliary Floating Dock, Lengthened
Steel dock similar to AFD's, but lengthened and enlarged to provide 1,900 tons lifting capacity.
YFD - Yard Floating Dock
This category included a wide variety of types, designed generally for yard or harbor use, with services supplied from shore. Among the principal types were 400-ton concrete trough docks; 1,000-ton, 3,000-ton and 5,000-ton one-piece timber trough docks; sectional timber docks ranging from 7,000 to 20,000 tons lifting capacity; and three-piece self-docking steel sectional docks of 14,000 to 18,000 tons lifting capacity.
These classifications were modified in 1946 in order to make the standard nomenclature of floating drydocks consistent and more descriptive. Four class designations were established, as follows:
AFDB - Auxiliary Floating Drydock Big
30,000 tons and larger.
AFDM - Auxiliary Floating Drydock Medium
10,000 to 30,000 tons.
AFDL - Auxiliary Floating Drydock Little
Less than 10,000 tons.
AFDL(C) - Auxiliary Floating Drydock Little (Concrete)
Under this re-classificaton, ABSD's were redesignated AFDB's; ARD's became AFDU's; RDC's became AFDL(C)'s; AFD's became AFDL's; and YFD's became AFDM's.
More details of the different dock specifications will feature in later posts. Some docks also carried names, which again, will be seen in ensuing posts.
During World War II, over 150 floating docks were constructed across the United States. They were included in the Navy’s Support Craft Category – “A grouping of navy-subordinated craft (including non-self-propelled) designed to provide general support to either combatant forces or shore-based establishments”.
A total of 78 docks saw service in advance areas. Commercial ship repair yards utilized 44, and continental naval activities, 21 docks. Three docks were furnished to Army ports of embarkation, two docks to the Coast Guard, and five to the United Kingdom; one was lost, and one was sunk in the Bikini tests.
"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
Last edited by Dreadnought : 30-11-2011 at 21:37. Reason: YFD2 lifting capacitychanged