Fred Wahl delivers 92' shallow-draft tug for the Alaska market

6/1/2010

Starting out, it was going to be like the Yukon, a 72-foot, shallow-draft tug we built back in 2006. But it just got bigger and bigger and bigger,” said Mike Lee with Fred Wahl Marine Construction, referring to the Dana Cruz, a 92'×36' triple-screw tug built for Cruz Marine in Palmer, Alaska. The tug was delivered in May.
The Reedsport, Ore., boatyard is known for building steel fishing boats that work the Bering Sea, Gulf of Alaska, and off the Pacific Northwest coast. But the boatyard has built a few tugs, including the Yukon, and like the just-launched Dana Cruz, they are shallow-draft designs intended to work Alaska’s western rivers and coastline.

The Dana Cruz will work these waters as well as the Chukchi and Beaufort Seas. To get up the rivers, the Dana Cruz has a 3'9" draft. When the ballast tanks are full, it will only draw 5'9".   

The Dana Cruz was to take the place of an existing Cruz Marine tug and pull a barge hauling heavy equipment and gravel. The tug is also equipped with push knees. But this year it will be chartered to Foss Maritime, said Cruz Marine’s Kevin Weiss. He added that the tug is “the only flat-bottom, load-line boat of its kind.”
AG McIlwain in West Vancouver, British Columbia, designed the boat, which has a steel hull and an aluminum superstructure and was built to ABS standards. The design is the first of the King River class.
Because the tug will be working in the Arctic’s shallow coastal waters and rivers, the bow has been strengthened to work in ice. To reduce the possibility of a fuel leak if the hull is penetrated, voids protect fuel tanks from side impacts. And with all electric winches, the crew won’t have to worry about the Coast Guard coming down on them for hydraulic-fluid spills from deck winches, which include a Markey TES-22 single-drum towing winch, a Markey DESMG-18S single-drum bow winch, a pair of Nabrico 40-ton face-wire winches, and a Markey VEP-12 anchor winch.

There is a hydraulic knuckle-boom crane, however, a Palfinger model PK 6500 NYB.
Down in the engine room, the three 600-hp Caterpillar C18 main engines with Twin Disc MG-5202 marine gears (3.48:1 ratios) are all flex mounted. The thrust from the Osborne 50" Superston props is mitigated by Aquadrive thrust bearings.

“That’s a good system with shallow-draft boats because it cuts out a lot of vibration. The boats cavitate like a son-of-a-gun because they are floating in such little water,” Lee said.  The props are housed in tunnels with heavy skegs beneath them for protection against ice, rocks and logs in the rivers. Using an Aquadrive bearing helps reduce stresses on the hull, but it’s also good in terms of crew comfort, which is important because crews working in western Alaska can be on board months at a time. In that regard, noise is reduced with the use of hospital super-critical-grade exhaust silencers on the main engines as well as on the two Cat C4.4 99-kw generators and a smaller Cat C2.2 30-kw genset.  


Rating:


Comment:

You must be logged in to leave a comment. Login | Register
Related Content

 
 
Diversified Business Communications