Manson Construction Builds Pacific Northwest's Heftiest Floating Crane

Wotan, a 600-ton lift crane mounted on a 300-foot-long barge (shown above) went into service on Puget Sound in mid-June. The floating crane, largest in use in the Pacific Northwest and one of the largest on the West Coast, was christened in June at the headquarters of Manson Construction & Engineering Company in Seattle.

The christening cermony started when a helicopter flew Henry Simonson, Seattle Port Commission president and Manson Corporate treasurer Tamara Amundsen, to the Wotan's aft helicopter pad. Mr.

Simonson was the principal speaker and Ms. Amundsen christened the vessel.

The ceremonies marked a golden anniversary for the 79-year-old company. It was in 1934 that the company acquired its first revolving, floating crane, according to Peter S. Haug, company president.

The Wotan is the 14th floating crane in the company's modern fleet.

The Wotan is rivaled in size on the West Coast only by the Betty L, a floating crane being operated by the Ocean Beach Outfall Constructors in San Francisco, a joint venture of which Manson is also a partner.

Manson purchased the 300 by 90 by 20-foot steel barge on which the crane is mounted in New Orleans.

The stoutly built barge will withstand a deck loading of 2,050 pounds per square inch. Capable of being submerged, the barge was sunk in New Orleans to load a crane barge; then, when refloated, the barges were towed to Seattle via the Panama Canal. In Seattle, Manson extensively modified and rebuilt the Clyde Model 42 revolving crane for mounting on the Wotan.

This crane, which revolves on more than 100 wheels driven by a huge bull gear, will lift 500 tons in the full revolving mode, but will hoist 600 tons over the stern. The boom offers three lifting points— the boom is 140 feet to the heavy lift tackle; another 35 feet to the two 100-ton lift auxiliary hooks; and another 15 feet to the whip, a utility hook capable of lifting 25 tons.

The boom and hoist is handled by five winches driven by a diesel engine.

The crane is controlled by an operator from a booth on the revolving structure itself equipped with controls, lift gauges, and communications systems. The operator can talk to the deck crew, Manson headquarters over company radio, marine traffic through VHF, and the anchor winch operator atop another winch house on deck.

Unless tied to a pier or other fixed structure, the Wotan will set anchors off four corners of the barge when preparing for a lift. Two-inch wire is guided through fairleads on deck from two, Model MD-97-EL four drum anchor winches built by Skagit in Sedro Woolley. Each of the four drum sets is powered by Detroit Diesel engines through torque converters. The drums have a cable capacity of 3,500 feet of 2- inch wire.

Electrical power is provided by two diesel driven interconnected generators. A 125-kw generator is located in the anchor winch house.

Another set located in the crane winch space in the rotating crane's base tub structure, turns both a 170- kw dc generator and a 60-kw ac generator.

DC power is used to propel the electrical motors that turn the full gear to revolve the crane.

Eight to 10 people can be accommodated in staterooms aboard. A full galley is equipped with an electric range, refrigerator-freezer, and laundry facilities. The pad structure is integrated with the aft wave break.

The barge is served by a pressurized water system. Water tanks will hold 67,000 gallons while fuel is contained in fuel tanks with a 134,000 gallon capacity.

Naval architect on the Wotan project was Robert W. Long of Seattle; the structural engineer was James A. Crim of Edmonds; and Manson Superintendent Robert L.

Stevens was project coordinator.

Other stories from September 15, 1984 issue


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