Towing the Dry Dock "Dewey"

American Machinist, Vol. 29, March 1, 1906
Towing the Dry Dock "Dewey"

Probably the most remarkable and interesting undertaking of its kind is that of towing the mammoth steel floating dry dock Dewey from Solomons, Maryland to Cavite, Philippine Islands. This dock was built by the Maryland Steel Company at Sparrows Point, which is just below Baltimore.

It is 500 feet long, 134 feet wide and a draft of 7 feet; the side walls are 42 feet above the water.

It was completed in June 1905 and was towed to the mouth of the Patuxent River where it was to be tested. On June 23, the USS Colorado was docked. This is one of the latest and heaviest of the amored cruiser type, and had a displacement of 13,300 tons at the time of the test.

The battleship Iowa was also docked on June 27, at which time the displacement was 11,600 tons. The specifications required that a 16,000 ton ship should be raised in four hours from the time she was placed on the blocks, until the keel was out of water. From the time the Iowa was placed on blocks until the keel was out of water was one hour and thirty seven minutes. The test therefore demonstrated that this dock is capable of exceeding the requirements in time of operating and capacity. It showed that a 20,000 ton ship could be docked so that all parts of the bottom would be accessible.

A novel feature of this dock is that it can not only lift a 20,000 ton ship out of the water but it can also lift itself out of the water so that its own bottom can be cleaned and repaired.

To describe how this can be done it will be necessary to refer to the sketches. The dock is made in three sections. The main section or pontoon is a rectangular box A with two side walls B. These side walls project over the main part of the pontoon on each end forming recesses as it were at C. In addition to the main pontoon, there are two end pontoons D, which fit into the recesses to make the affair complete for docking a vessel. Now when it is desired to get at the bottom of the main pontoon, the end members D are sunk by opening valves and filling the compartments until they can be floated under the main pontoon after which the water is pumped out until that pontoon is floated so that there is a clearance of five feet between the bottom and the water. The end pontoon can be cleaned by sinking the center one and floating the ends onto it the same as a ship would be docked.

The cost of this mammoth dock about one and one quarter million dollars. It contains 11,000 tons of plates and is held together by about 2 000,000 rivets; it required about 130  tons of red lead and oil to paint it.

Wonderful as is the dock itself, more wonderful is the fact that the Government is to tow this craft across the broad Atlantic, through the Suez Canal and Indian Ocean to its destination at Cavite PI, a distance of about 12,000 miles. It is expected to travel about 100 miles a day, which will make the total time required for the trip about four months. 

To tow this dock the Government has detailed the supply ship Glacier and the colliers Caesar and Brutus The Brutus will be next to the dock with Caesar next ahead and the Glacier in the lead. The tow will be a mile and a half long, which is the longest in history. The Government has taken every precaution possible to insure the safe arrival of the dock at its destination. The most important part of the apparatus for towing is the Shaw & Spiegh automatic towing machines, which are made by the American Ship Windlass Company of Providence RI, and one of the largest sizes of which has been installed on each of the three steamers mentioned. These machines are installed on the stern of the steamers and each carries a 1,200 foot steel wire hawser, 2 inches in diameter. To the end of the hawser on the Brutus will be attached a manila hawser 5 inches in diameter, doubled, which will be 600 feet long and attached to this will be a bridle made of 2 1/2-inch chain and 270 feet long, the ends of which are made fast to two sets of double bitts or towing posts which are on the dock. The peculiar feature of the towing machines before mentioned is that when a strain comes on the towing hawser which is greater than the machine is set to stand the machine will run backward and pay out the hawser and in doing so it opens a valve automatically which allows more steam to pass into the cylinders until the pressure in the cylinders equalizes the strain on the hawser. Then when the extra strain on the hawser has passed there is of course too much steam in the cylinders to balance the normal strain on the hawser and the latter is therefore wound in again to its normal position and the valve closed. This operation is repeated as often as a heavy sea strikes the dock and it will therefore be seen that this machine affords great elasticity in the tow line, and prevents it from parting as would be the case under ordinary conditions. One of these machines was also used for towing the dock which is at Algiers, LA.

In addition to the three steamers mentioned the US tug Potomac is to accompany the dock as a despatch boat. This tug is also fitted with one of these towing machines.

Commander H.H. Hosley, who is the Supervisor of New York Harbor, has been temporarily relieved so that he may take charge of this expedition. Capt J.D. Wood who has been master of tugs at Norfolk, is to have charge of the dock itself. There will be two crews on the dock during the trips, a deck crew of sailors and an engineer crew. They will live in the side walls of the dock, which are provided with nine staterooms for the officers and ample accomodations for the crew. There will be a complete distilling apparatus for making fresh water and the men will be abundantly fed as the usual rations have been doubled. It will cost $25,000 in dock fees alone for the dock to pass through the Suez Canal, and in addition to this, all of the buoys in the canal will have to be taken up and then reset again, as the dock is 134 feet wide and the canal only 150 feet in the narrowest place; this expense our Government will also have to pay. There has been about $75,000 expended for towing gear such as towing machines steel and manila hawsers, chains shackles, etc., besides the expense necessary to fit up the steamers for this work and the expense of running the steamers and paying the crews of steamers and dock until it reaches its destination. It will therefore cost probably all told about $250,000 to deliver the dock and for the steamers to return.

It is certainly a great undertaking; it will be watched with a great deal interest until the arrival at Cavite, as all the steamers and the dock are supplied with wireless telegraph so that probably reports will be very often. Each steamer is also fitted with a powerful searchlight which be kept on the tow line astern of it, as to prevent any vessel from running across it on a dark night and cutting in two.

The dock has been fitted with the anchor windlass that was formerly on USS New York. This was also built by the American Windlass Company. It handles four 2 1/2-inc chains, two of which will be used at end of the dock with a heavy anchor each chain.

[The original document from which this article was transcribed can be found here.]