2015: Will Maine Lobster Men Try a Trimaran?

Updating the Maine Lobsterboat                      Copyright Peter Marsh

The traditional Maine lobsterboat has inspired many designers to create motor yachts that incorporate this working boat’s classic combination of a semi-planing hull and well-proportioned pilot house. The best know of these is probably the Hinckley Picnic Boat, which has in turn inspired dozens of imitators. Now the fishermen have turned the tables and sponsored their own development—but this has led them into uncharted waters where yachtsman and fishermen fear to tread.

lobster tri GreenBoats1It was the cost of fuel that was the catalyst for this project, and may scuttle it now that the price of oil has dropped so far, but fuel efficiency still seems a worthwhile goal to many north-western boaters. And who knows how long the price will stay low? It was in 2010 that the Penobscot East Resource Center contracted with Maine Maritime Academy in 2010 to research a new lobster boat design. Doug Read — a naval architect and professor at Maine Maritime Academy—led the project.

He held several meetings with fishermen, talking about what challenges they faced and what they’d like to see in a new design. The average lobster boat travels 60 to 100 miles per day and burns approximately 3,000 gallons of fuel per year, he learned. “The current lobster boat design has evolved over many years of fishing and boat building, and it’s very, very good at what it does. The current hull can’t be made much better without really doing something a lot different,” he explained. “They want wider and wider boats, but when you do that, you drive up the power requirement.”

lobster tri bow GreenBoats2To make a radical improvement in fuel efficiency – 25-30 percent – is going to require a radical leap in the shape of the hull, he realized. “If we go to a multi-hull design, you can sort of separate the wide beam from the power requirement.” Initial tank testing of models showed a 30% fuel savings.  In May, after three years of design and construction work with his students, they had their one-sixth scale models of a 38′ triple-hull or trimaran design and a conventional lobsterboat shipped to San Diego, Calif.

There they had contracted with an outdoor testing center that utilizes a similar tri-hull as a towboat that rigs a pair of models—one on each side of the bow—away from its wake and accurately measures their motion in varying sea states. The results went exactly as predicted. “We proved the power reduction we were expecting, side by side against a modern Maine lobster boat,” Read said. Not only was fuel efficiency up between 20 and 25 percent, but the boat was stable in the water despite the unorthodox hull design. “From what we saw, it handled the water quite well,” Read continued. “The motions were comparable to the traditional boat.”

lobster tri modelThere’s a lot of 3D design work behind this, but it can be understood pretty simply by looking at a typical wake, he explained. “Up to half of your engine output is dedicated to the energy it takes to make those waves in your wake. The center hull is really narrow, about 3 feet wide. That’s where you’re getting the fuel savings. The trimaran drastically reducing the energy you spend making those waves.”

“Making a trimaran look right is kind of hard,” he admitted. “I’m making incremental progress. The side hulls are like training wheels. Ninety-seven percent of displacement is on the center hull. And the other three percent is the side hulls.” The trimaran reaches peak efficiency between 12 and 18 knots with around 25 percent increased fuel efficiency.

But that does not apply at all speeds. Above 20 knots, traditional boats begin to hydroplane and become more efficient. But the fishermen agreed the 12-18 knot speed is fine for the way they use their boats. Efficiency and stability aren’t the only things that matter to Maine’s lobster men, said Robin Alden, executive director of PERC. She said that while the fishermen consulted by PERC and Read were supportive of the project, they had one condition: it’s got to be pretty!

“The traditional lobster boat means a lot to people,” she said. “That aesthetic…..nobody wants to be on some square boat. Doug has figured out how to create a trimaran hull that will look very similar to the traditional boat above the waterline.” There was keen interest from lobstermen at the Maine Fishermen’s Forum when the design was unveiled. Next steps: fine-tune the design and construct a full-size prototype.

Given its reduced drag, he said a 38′ trimaran equipped with a 175-horsepower engine would use 9.3 gallons of fuel per hour at cruise, and 2 gallons per hour at idle, which compares with an average of 13 gallons per hour at cruising speed on a monohull equipped with a 250-hp engine. He calculated the savings would add up to 16 gallons per day.

Read said he examined other solar and diesel-electric options, including the use of a generator and hydro-electric technologies. But the current state of the art adds weight or undue complexity, or both, to a boat’s already complex systems – without providing a significant savings when running the boat at a cruising speed.

Author’s note: I’m glad to see some fishermen are finally showing interest in multihulls—though no one is rushing to build the new design. But the idea of spending four years researching the concept appears to me like re-inventing the wheel. After all, the motor trimaran is not exactly a new idea: the US Navy has already commissioned one 418′ trimaran littoral combat ship from the Austal yard in Louisiana, with another well on its way–and eight more ordered!

 

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