GREEN BOATS continued from Home Page

“PERC is all about preserving a fishing future for Maine fishing communities,” PERC Fisheries Science and Leadership Advisor Carla Guenther said in her introduction of Read. “This particular project came up in response to fuel prices and looking at the profitability of fishing businesses, mainly lobster.”

Read said he began by analyzing the functions and general performance characteristics of current lobster boats.

He said the way the current lobster boat has evolved over the decades is “impressive” in terms of its general sea-handling capabilities and operational requirements.

The operational profile of any lobster boat is critical to is design, he said. This includes speed, duration of a trip, and trap-hauling requirements. Hull design, propeller configuration and type of engine tie into a boat’s performance, he said.

A typical lobster boat has a narrow entrance angle and round bilge, he said, the latter translates to a large wetted surface area, which results in drag.

A beamy, or wide boat, runs counter to concept of drag-reduction, he said.

Read said one of the best ways to save fuel is not to run the boat fast. But, he said, that was an unlikely scenario for a workboat that might travel 60 to 100 miles per day and needs to run at a reasonable speed to get out and back in a timely manner.

Read said he looked the possibility of incorporating solar panels on an extended housetop, as a way to run a combined solar-diesel engine, but the savings were minimal.

“If you extend the housetop on a lobster boat and cover it with solar panels, you get 5 horsepower in full sun,” he said. “That’s not enough even to run a pot hauler, probably. It’s not going to get you going very fast.”

If the boat were equipped with a bank of batteries to store solar energy collected while the boat was sitting on its mooring, some fuel would be saved, he said.

“But is it worthwhile to add batteries and electric motors to the complexity of the boat to get that? Right now, I don’t think so,” he said. “If diesel goes up to $10 per gallon, maybe yes.”
Read showed a slide of a catamaran designed for recreational outings; the decks of the dual-hulled boat were entirely covered with solar panels – and still could only get up to 5 knots, he said.

Read said he examined other diesel-electric options, including the use of a generator and hydro-electric technologies. But the current technology, he said, tends to add 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.

“The part we’re saving money on is the idling fuel consumption,” he said of the alternative engine technologies.

Idling the boat, which occurs when the fisherman is hauling traps, consumes about 2 gallons of fuel per hour. At cruising the speed, a typical lobster consumes between 13 and 25 gallons an hour, he said.

“So if you’re adding all this technology, complexity and weight to improve the 2 gallons an hour, and you’re leaving the 13-25 gallon an hour alone, you’re chipping away at the wrong piece,” he said.

Read said the alternative was to look at hull form.

“The proposal is to go to multi-hull,” he said. “The current lobster boat design has evolved over many years of fishing and boatbuilding, and it’s very, very good at what it does. But to make a radical change, a radical improvement in fuel efficiency – not just 5 percent but 30 percent – is going to require a radical leap in the shape of the hull.”

Catamaran and trimaran designs have lower hull drag in the water and yet are beamy above the water and stable overall, he said.

Read said that, in designing a new type of lobster boat, stability and deck area requirements must be separated from drag characteristics.

“That’s the key,” he said. “Because if beam and deck area are coupled together, then the drag is going to keep going up. And the power is going to go up. This is the way to get around it. The really narrow hull cuts down drag quite a bit.”

Read said that trimarans provide the same stability as a monohull in heavy seas. For fuel savings, a 36-foot trimaran is most efficient at speeds of 16 to 20 knots.

“I think that a 30 percent improvement in power, a 30 percent reduction, is quite possible,” he said. “That’s huge. A 30 percent reduction in drag equates to a 30 percent reduction in fuel consumption.”

Read said he based his calculations on a fishing day that involves four hours of cruising time and two hours of idling while hauling traps.

Given its reduced drag, he said a 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.

“It’s a radical change,” he said of the trimaran concept. “But I think the power reduction is very achievable and I think the impact is significant enough to pursue it.”

Read said he is still working on the design of a tri-hull lobster boat.

“Making a trimaran look right is kind of hard,” he said. “I’m making incremental progress. The center hull is really narrow, about 3 feet wide. That’s where you’re getting the fuel savings. The side hulls are like training wheels. Ninety-seven percent of displacement is at the middle hull. And the other 3 percent is the side hulls.”

Read presented slides of drawings of a possible tri-hull configuration. There was a gasp from the audience when they saw how narrow the center hull would be.

“The hardest part might be breaking tradition,” another man said of the design.

“Certainly,” said Read. “As I said, it’s a radical change to go to something like that and I don’t know how it’s going to go. To get that kind of radical improvement, I think we need to make a radical change. The current hull can’t be made much better without really doing something a lot different.”

Read said he will study the design further to determine its sea-handling abilities.

“You need to build one,” one man told Read.

Read said he will be conducting tank tests of a 5-foot model at MMA this spring.