Alaska tug will boast a draft of only 36.
Fred Wahl Marine building triple-screw tug

1/1/2007

From the waterline up, the 72' ⋅ 30' triple-screw tug being built at Fred Wahl Marine Construction for Ruby Marine in Nenana, Alaska, isn't much different from boats that work on the Mississippi River system.

Below the waterline, however, there's a distinct difference. "She's missing half a hull," said Matt Sweetsir, who heads up Ruby Marine. That's because the boat, which was designed by Entech & Associates, Houma, La., only draws 3'6". To get that shallow, the 38" props are tucked up into tunnels.

"The tops of the propeller blades are just about at the waterline," said Mike Lee, general manager for Reedsport, Ore.-based Fred Wahl Marine.

The shallow draft is necessary because of the rivers the tug and its two 150' ⋅ 40' ⋅ 6' barges will ply. The 72-footer will push loads of fuel and freight on the Yukon, Kuskokwim and Nushagak rivers in western Alaska.

Portions of the rivers are particularly shallow in the spring and fall. "If we don't have three-and-a-half feet, we are not able to get to all the villages," Sweetsir said.

There are a couple of other aspects to the tug's operation that aren't found in the Lower 48. Besides seasonal shallow water, the rivers quickly freeze during the minus-60º winters. Thus Ruby Marine's tug will either be tucked away in a slough or hauled up on the beach for the winter.

To prevent pipes from freezing during the winter layover, the plumbing is designed to be easily drained. "Even if the runs don't look good, they need to have slope and cleanouts to get the water out," said Lee.

Between freezes, the rivers are navigable for only about four-and-a-half months. "It goes from the last week of May to early October. Five [months] would be great, but I've never seen it," said Sweetsir.

With such a short season, there's no crew rotation. The crew that arrives in May stays "until the boat is put away," he said.

Thus crew comfort is especially important. Lee said there's a recreation room on the boat. The boat is also air-conditioned. Granted, the temperature only gets to about 85° for a month, but Sweetsir said he wants to do everything possible for the crew to get plenty of rest, which can be difficult when there is daylight 24 hours a day. To reduce engine noise, the overhead in the engine room has plenty of sound-dampening insulation.

The main engines are three 500-hp Lugger diesels. There's also a pair of 55-kw Northern Lights generators, which will be used mostly for hotel power.

On the foredeck will be a pair of Nabrico 40-11-14 five-hp electric winches, along with one Nabrico 40-11-M hand-operated winch.

The all-aluminum house has three levels. The hull, main deck and trunk on which the house sits are steel. The top of the 3' raised steel trunk is the engine room's overhead. Without the raised structure, there would only be 4' between the main deck and the bottom of the boat, hardly enough space for an engine room.

The tug will be delivered by early April. Ruby Marine's two 150-foot barges are under construction at Beoufway Contractors ' Louisiana facilities in Houma and Amelia.

- Michael Crowley


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