MGBW building new compact, robust yard tug

DECEMBER 16, 2016—Shipyards that build and repair oceangoing vessels often employ their own small yard-tug to maneuver in and around yard structures, reposition hulls in dry docks or to control newly launched vessels.

General Dynamics NASSCO in San Diego, CA, is no exception. For years, the shipyard employed the tug Mr. Ed. But when it came time to replace the tug, the shipyard management worked with Seattle-based naval architectural firm Jensen Maritime and Marine Group Boat Works (MGBW) to design and build a tug that is specifically for shipyard work, robust enough to endure long hours each day, while minimizing the resources needed to operate and maintain it. The resulting tug is an attractive, compact, steel-hulled boat that can be operated by a single person.

The 38 ft by 15 ft by 5.5 ft tug is currently under construction at MGBW’s new solar-powered construction facility in National City, CA—conveniently located less than five miles from GD NASSCO. Besides moving vessels being built at the yard, the new tug will be used  to deploy pollution containment booms. Work in the often-tight corners of a shipyard requires excellent visibility, so the designers have given the pilothouse a 300-degree unobstructed line of sight. In addition, a flying bridge, complete with communication and control consoles, is an integral part of the wheelhouse.

For pulling power, the tug will have two Cummins QSL9M Tier 3 engines, each producing 410 horsepower. The engines will drive 38- by 26-inch four-blade, bronze, workhorse-style props on 3-inch Aquamet 22 shafts. Each engine is linked to the shafts via a ZF325-1 gear with 2.97:1 ratio.

The Cummins propulsion is expected to give the tug a speed of between 9 and 11 knots. It will also deliver between 18,000 and 20,000-pounds of bollard pull. On-deck tow-bitts are mounted fore and aft to exercise the pulls.

In addition to conventional rudders the tug will be fitted with flanking rudders for enhanced maneuverability and handling. Tankage will include 1000 gallons of fuel. A Fast Lube Oil Change System (FLOCKS) negates the need for lube and dirty oil tanks. There will be a 5-kW 110-volt generator for electrical requirements. The delivery of the Workboat 38 is scheduled for the summer 2017.