Railway Drydocks Designed By Crandall Recently Completed And Now In Operation

The construction of three modern, highly efficient, low-cost marine railway drydocks designed by Crandall Dry Dock Engineers, starting with the 4,000-ton railway at Jacksonville, Fla., followed by a 3,000-ton at Pago Pago, American Samoa, then another of 4,000-ton-capacity at Punta Arenas, Chile, and finally the enlargement of the railway drydock at Pictou, Nova Scotia from 2,000 to 3,000 tons, demonstrates the acceptance by shipyards of the durability, reliability and economy of railways, especially when their modern design is found quite acceptable to the environmental authorities. Also, U.S.

naval authorities have granted 100 percent of their commercial capacity in their certifications of these.

The railway drydock, due to its extensive underwater track, is limited in most shipyard sites as to size and capacity, but when a virgin site is chosen whose open water space is not limiting, they can be economically built up to 10,000 tons. This is the situation at Atlantic Dry Dock, Dartmouth Marine Slips and Pictou Industries where deep water was available just offshore.

Today, there are several engineering developments making the larger railways more attractive.

1. Welded chain with a factor of safety of 4 can be produced in either class 3 quality or the new class 4 quality, making it possible to haul 4,000- to 5,000-ton ships with only two chains versus the old four-chain and six-chain docks using cast steel chains.

2. New two-way steel track, fabricated in sections 40 to 60 feet long and supported on highcapacity steel piles lends itself much better to heavy waterfront construction methods and the finished product is free from marine borer attack and, with proper paint, is very durable under water.

The well-proven transfer systems adjacent to the cradles enable shipyards to use their transfer area for long duration repairs or new vesself construction at a very modest cost and the system does not require a wasteful cross-transfer area when real estate is at a premium.

In spite of its perception as an old type drydock, the railway of today is a modern, welldesigned and constructed facility. It can be made with declivities that suit natural shore conditions and has a superb record of safety in that the vessel is supported at all times and survives remarkably even when overloaded, neglected and abused. Its inherent durability in the harsh environment of the sea makes it very attractive in its capacity range of 100 to 10,000 tons.

For free literature giving complete information on Crandall Dry Dock Engines, Circle 50 on Reader Service Card

Maritime Reporter Magazine, page 44, Jan 1988

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Maritime Reporter

First published in 1881 Maritime Reporter is the world's largest audited circulation publication serving the global maritime industry.