Green Boats Set For Testing

by Mike Crowe



Side view of three hulled experimental lobster boat. Projected efficiency is above 30%. Three 7 foot models will be comparatively test in late spring in California. MMA Graphic

 

A highly efficient lobster boat hull design is scheduled to be tested in San Diego, California this spring. Maine Maritime Academy naval architect Doug Read designed the trimaran hull that will be tested by the M Ship Company. In tanks tests at Webb Laboratory in Long Island, New York, this past summer another model indicated the trimarran went through the water with 30 percent less resistance.

Next spring three 7-foot models will be tested. Maine Maritime Students Gordon Smith of Beals and Tom Morrison of Waldoboro will build a conventional lobster boat hull design for accurate comparison and two trimaran type hulls at 1/5 scale for comparative stability tests. Smith has had experience with model building for lobster boats. Both come from fishing families.

The models will be tested on a device used to test vessels for the U.S. Navy. The Webb tank tests measured resistance, but could not assess stability. The models will be suspended from a boom over the side of the test vessel. Instruments on the test vessel will be wired into the models. Testing will be done in San Diego Harbor.

Following the Webb tank tests, Read said a lobster boat using the trimaran hull design could run at 16 to 18 knots with a conventional 200 HP engine. He also said known propeller modifications could produce additional savings.

Cross-section of the experimental trimaran lobster boat hull designed by Doug Read of the Maine Maritime Academy. The greatly reduced wetted surface increases efficiency, which was trested this summer. Next sping stability tests will be done. MMA Graphic

 

At a November 5 meeting at Penobscot East in Stonington, Maine, the following marine engineering points were discussed.

• “V-Cubed,” means if you want to go twice as fast, you will burn 4x as much fuel.

• Even if the entire boat were covered with solar panels it would only get approximately 5 hp. Solar is just not efficient yet.

• The prime reason to not use a catamaran design is that they use 2 engines-more difficult to work with and to fix.

• All testing was done in comparison to the Frost lobster boat Doug had found originally.

• Because of the speed needed to simulate testing they had to go to Webb Institute in NY to do all testing because the test tanks at UMO cannot go fast enough. Test boat needed to be pulled 12 ft per second

In testing, Read was able to use a MMA “printer” to print five different stern designs. This “printer” creates actual hardware that he was able to attach to the model.

This allowed testers to try nine different test positions, between the stern designs and the positioning of the two outside hulls.

For testing flexibility the two stabilizing hulls are re-positionable.

“No hull is good at every speed,” said Read—the faster the boat goes the less efficient it becomes.

Propellor efficiency is very important, and often overlooked, he added. Changing the prop can increase efficiency by 2-3 percent, which can translate into huge savings. The project needs funding, but Read would like to focus on propeller design next school year.

The actual boat would likely be built with fiberglass.

Asked if it would be possible to change the width of the boat when situations called for it, Read said, that it would add complexity to the design, but that he did not see why it wouldn’t be a possibility, should someone want that done.