Arctic classJul 2, 2014 02:10 PM
Foss building clean, powerful boats to support Arctic oil and gas operations
Photos by Brian Gauvin
Don Nugent, head of Foss Rainier Shipyard, stands in front of a mid-hull module for the first of three ice-class tugs.
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The people involved in the development of Foss Maritime’s Arctic-class tugs don’t expect the company’s three new 130-foot ocean-towing boats to be revolutionary, but they do expect them to be among the best in the world.
Foss has tried to draw on some of the best thinking on tugboat design and operations — much of it from its own in-house expertise — to create a tug that can operate safely and efficiently in even the most extreme settings, notably the Arctic.
“We’ve integrated design features to make it able to go anywhere in the world,” said Dan Cole, Foss project manager.
The first boat is due for delivery in December. The next two are expected to be ready in December 2015 and December 2016. These will be powerful tugs, with bollard pull of over 100 metric tons. Rated at 7,268 hp, the boats will be powered by dual Tier 2 Caterpillar C280-8 diesels.
Foss — which expects the boats to support the petroleum industry’s search for oil and gas around the world, and under the Arctic Ocean in particular — has a great deal of experience in the far north.
The engine room under construction. The tugs will be powered by two Cat C280-8 Tier 2 diesels generating a total of 7,268 hp.
“Foss has a longstanding commitment to Alaska and the Arctic,” said Mike Magill, Foss vice president of technical services. “There hasn’t been any marine work up in the Arctic that Foss hasn’t been involved in.”
Foss is building these boats largely in response to the opening of the Arctic to offshore oil and gas development. “Most people agree the Arctic will provide some unique opportunities,” Magill said.
For example, the boats could be used to haul barges that carry the equipment needed to cope with a spill. “We are their protection for blowouts,” said James Daley, Foss director of operations, global services.
The major oil companies decide which boats it wants to support its operations. And bollard pull will be one of the key criteria. High bollard pull is “the ticket you need to play,” said Jay Edgar, president of Glosten Associates, the Seattle naval architecture and marine engineering firm that designed the Foss Arctic-class tugs.
While raw power is crucial, the boats must also be able to operate safely and reliably in some of the most challenging and environmentally sensitive areas of the planet. That requires robust structures that can withstand impacts with ice.
The Foss tugs have been certified by the American Bureau of Shipping as meeting the standards of Ice Class D0. The power train — including gearboxes, shafting and propellers — has also been beefed up. The diameter of the shafts and the thickness of the propellers have both been increased to withstand the shocks of ice operations.
Foss also asked Nautican to provide a custom design for the integrated propeller, nozzle and high efficiency triple-rudder system. The nozzle is attached to a head box that extends up into the hull. The idea was to create a solid connection between the hull and the nozzle, so that when ice strikes the nozzle and propeller, the forces will not stress the propeller shaft.
The integrated Nautican system, which includes pre-swirl stators, contributes to the power and efficiency of the propulsion system. The stators deflect the flow of water as it enters the props in a way that improves the way the props bite into the water.
Douglas M. Wolff, Foss director of engineering, said the Nautican system contributes to higher bollard pull, while improving fuel economy. The system adds about a quarter knot to the boat’s speed, while improving fuel efficiency at all speed ranges.
The boats will have a multitude of features to help them cope with extreme cold. Accumulation of ice on a vessel can pose a threat to its stability. Clearing that ice can be a difficult, exhausting task. To counter ice buildup, the inner sides of the bulwarks have been enclosed with vertical steel plates, creating flat surfaces.
“It gives you less surface area for ice to collect and it’s easier to clear,” said Cole, the project manager.
The sea chests, which admit the water for cooling the engines, have to be kept ice-free. They have been equipped with heaters to prevent ice from clogging them.
For a vessel operating in the far north, the issues of structural integrity and systems reliability are closely related to safety and environmental protection. A vessel that loses propulsion or begins taking on water as a result of ice damage becomes a danger to its crew and to the environment. The pristine state of the Arctic means that even in the course of ordinary operations, no discharges are acceptable. The Foss boats were designed with that principle in mind.