In August 2013, the JT Marine Inc shipyard in Vancouver, Washington delivered the MV Hawaii, the first of a pair of 120-ft ocean-going azimuthing stern-drive (ASD) tugs designed by Jensen Maritime, Seattle naval architects, for Hyak Maritime LLC. The tugs are based on the Titan-class ASD tugs developed by Jensen and Western Towboat, the Seattle-based tug and barge company that operates a weekly barge service year-round between Seattle and Alaskan ports. Western Towboat has built 17 of its vessels in its own yard and is now constructing its seventh Titan-class tug.
The new Hyak tugs have a 35-ft beam and 19-ft draft and, like the Titans, are propelled by a pair of Schottel 1515 FP ASD-drive units with 2600 mm diameter stainless steel propellers which provide superior manoeuverability of barge tows in berths and restricted waters. Unlike the Caterpillar-powered Western fleet though, Hyak has selected General Electric (GE) 8L250 EPA Tier II engines. This is a medium-speed engine rarely seen to date in tugs. But, like the rival two-stroke EMD diesel, it is well-tested in locomotives.A design standard for ocean and coastal towing
The co-owners of Hyak Maritime, Gordon Smith and Robert Dorn, are both experienced tug skippers and have a long-term goal to establish this design as the new standard in US coastal and ocean towing. The Hyak boats are built to the highest standards of ABS + A1, AMS Machinery Class, Towing Certification All Oceans, with the Marpol compliance necessary to work in international ports.
Smith and Dorn consider the Western Towboat tugs to be superior vessels as demonstrated by the many years experience of owners Bob and Ric Shrewsbury, port engineer Ed McEvoy, and the Western crews over the toughest Pacific routes. “Our goal was simply to modify the Titan to suit the widest range of towing demands,” Dorn said. “The result is the tug I have wanted to own and operate for the last 20 years of towing around the Pacific.” He adds that Western Towboat has proven the ASD drives to be particularly useful for their tugs to manoeuver the large barges into berths unassisted. This save time and money and in some remote Alaskan ports there aren’t assist tugs available in any case.
Smith and Dorn’s survey estimated there are over 300 offshore tugs in the US in the 4,000-6,000 hp category, most of which are built to traditional single- and twin-screw designs with engines that do not meet modern emissions standards, are in violation of MARPOL rules and cannot sail to foreign ports. Since their new boats are intended for long-term charter, Hyak has specified that all systems meet these standards and are simple to operate and maintain.
Propulsion considerations
The owners carefully considered their choice of diesel with an eye to greater reliability and fuel economy, rather than to initial cost. “I budgeted an average of $350,000 a year in maintenance and repairs on a 5000-hp tug during my days at Sea Coast and Sirius towing ocean tank barges,” Dorn recalled. “With the new Titan tugs we can expect to save more than 800 gallons of fuel and 30 gallons of lube oil daily over the conventional Sea Coast or Sirius line-haul tugs.” The spec sheet he has printed for the boats projects significant fuel savings over a high-speed four-stroke engine of equal power, and dramatic lubricant savings over ‘standard two-stroke medium-speed engines.’ The Hawaii’s fuel capacity is 158,000 gallons; The sheet also predicts that the overhaul interval will be 40,000 hours, or about seven years. The engine also require no after-treatment and can be upgraded to meet Tier III emissions standards.
During sea trials, the Hawaii exceeded Jensen’s 80-ton bollard pull prediction, measuring 82.5 tons and a 14.5-knot free-running speed. “This was even better than we expected and it means that our performance standard — the fuel efficiency of a 4,000-hp boat that pulls like a 6,000-hp boat– has been fulfilled. Gordon and I are grateful to Western Towboat and Jensen Maritime for allowing us to use their proven design,” Dorn explained.
Pilothouse and accommodations
The aluminum pilothouse was pre-fabricated by Hi-Tech Metal Fab (no–an arm of JT I think) and has good all-round visibility with a typically narrow ASD layout with port and starboard ASD control sticks. Both winches are fully visible and controlled from the main helm position. The extra width of the 12-ft wide house permits a full-size chart table and pair of comfortable seats outboard facing forward.
The house and forecastle are fitted with top-of-the-line equipment to ensure crew comfort. The living quarters can sleep eight in four crew cabins below the main deck, with the mate’s and master’s stateroom on the deck level, along with the spacious mess and galley, which is equipped with restaurant-grade equipment like the large Cospolich reefer and freezer, Lang stove, and Insinger dishwasher. All cabins are acoustically dampened and fireproofed to the highest international crew comfort and safety standards, with a Daikin HVAC system controllable in each cabin or crew space. Fresh water tankage is 11,000 gallons. All emergency lighting is by LED, Harris Electric built the switch boards, the fire-control system is by Fireboy, and Hockema & Whalen designed the electrical system.
Propulsion
The GE diesels are each rated at 2679 HP/1999 kW at 900 rpm for a total of 3998 kW in each of the new Hyak tugs tug. They weigh almost 44,000 lbs apiece and stand some 11-ft tall. The unitized cylinder assembly includes cylinder head, intake and exhaust valves, valve linkage and a high-pressure fuel-injection pump and nozzle. They are turbo-charged and inter-cooled, coupled to the Schottel 1515 FP ASD thrusters via Centa flexible connectors and carbon-fibre shafts.
Gen Sets
Two John Deere 6081A/Kohler 195 kW gensets each provide electrical service and each is also plumbed to provide full hydraulic power to the winches. Engineering was by Crescere Marine Engineering of Columbia City OR Oregon. The bow winch is a JonRie Series 200 with capacity for 150m of 60 mm (7-inch) plasma line, a line pull of five tons, a line speed of 20m/minute and a 200-ton brake capacity with an independent capstan. The winch features JonRie’s Joystick feather speed control, auto render block and fail-safe brakes.
Winch
The stern winch is a JonRie Series 500 double-drum towing winch with a capacity of 750 m of 60 mm (2,600 feet; 2 ¼-in) tow wire, a line pull of 70 tons, a line speed of 25m/minute with a brake capacity of 285 tons. The auxiliary drum has a capacity to spool 550m of 50mm hawser (1800 feet of 2-in wire), a line pull of 50 tons, a line speed of 30m/min with a brake capacity of 285 tons. The winch features JonRie’s independent level wind and gypsy head that can all be operated from the pilothouse. Both drums come with JonRie’s auto abort system and controlled free wheel system to feather line out at a rapid pace and feather back so the tow line will not jump out of the water.