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"These boats should be able to provide a steering force for an LNG tanker of as much as eighty tons while the ship's mov- ing ahead at eight knots, which in essence means the tug is getting dragged more or less sideways through the water at eight knots. That required a significant increase in the beam of the boat, and a different resistance in the water." Said Bruce Doughty, "They've been building escort tugs for some time, so the escort keel is not an innovation. But Bull- dog's is a refinement. It's taking things that people have learned over the years and going maybe a step further for a little more efficiency. We went to Gloston Associates on the west coast. They've done a lot of research and have developed their own program for predicting steering forces and so forth, and we hired them as consultants. The gas company itself had Greg Brooks, who's watched a lot of tank- testing and so forth; and his ideas were incorporated, along with some of our own input." Balancing Act At the fulcrum of the balancing act of the new boat's design was Moran's varied uses for the tugs. There would be plenty of escort, but plenty of normal shipdocking as well. They're not mutually exclusive as design requirements go, though some of their specifics are opposing. "Moran having the experience with the 92-footer," said Mr. Washburn, "and Cres- cent having worked alongside the 92-foot- ers down in Savannah, they didn't want to sacrifice too much of the turning and han- dling characteristics of those boats. So we carried the keel back a little further than you would on a normal, pure escort boat, to add a little more drag. It seems to make a boat that tracks pretty well, a good com- bination of steering and straight-line run- ning characteristics, which is what we were striving for." Said Mr. Doughty, "from the feedback we're getting for the Bulldog we've hit it pretty good. And they're comparing her to tugs that are built just for shipdocking." Mr. Doughty notes that the 98-footer could also be delivered without the escort keel, should it be so desired. The word "partnership" is used loosely in corporate relations, though in the case of Washburn & Doughty and Moran, there's an acknowledgment of successful interdependency. "We probably wouldn't have won the navy contract," said Ted Tregurtha at the launch, "except you came through." The "you" was the workers of the company — described by Moran chairman Paul Tregurtha as "real boat builders." "One of the things that kind of sets our crew apart," said Mr. Doughty in his office on March 1, "is that they are setting the pace and taking things on without April, 2006 • MarineNews 23 ALL WEATHER PROTECTION ™ from Carolina Cockpit Inc. Light Weight, Corrosion Proof Pilothouses and Cabs Designed and equipped to your specifications and ready to install aboard vessels and equipment. All models include: Aluminium framed, tempered glass windows Door & window locations to order Stainless steel hardware ABS, DNV, GL Approved Carolina Cockpit Inc. 225 Alexander Rd, Portsmouth, RI 02871 Ph: 401.683.1661 www.carolinacockpit.com Circle 261 on Reader Service Card It takes a big propeller to move a tug against an LNG tanker underway. The pair on the Edward J. Moran are attached to Rolls Royce US 255 Z-drives, driven by two EMD 12-710-G7B main engines, bollard pull given as 176,760 libs. ahead, 170,000 astern. (Photo: Don Sutherland.) APRIL MN2006 3(17-24).qxd 4/7/2006 3:06 PM Page 23
