Roll Dampening on the Grand Banks

Longtime Newfoundland fisherman Vernon Petten of Port-De-Grave isn't afraid of trying something new. For his most recent boat, 65 x 23-ft. Newfoundland Clipper he installed his first Cummins in the engine room and up on top of the boat's shelter deck, he installed his first roll dampener. He chose the 600 hp Cummins KTA19-M3 main engine because of the company's good service reputation. He installed the anti-roll tank because, unlike the more common "flopper-stoppers" which can cost the boat one knot of speed, the tank allows the boat to maintain its regular speed. Designed by Dr. Don Bass, at the Faculty of Engineering and Applied Science, at Memorial University of Newfoundland, the tank on Petten's boat is built into the shelter deck cover a few feet aft of the forward mounted deckhouse. Extending nearly the full width of the boat, it is 20 ft. long by about 4.5 ft. high. The middle of tank narrows to about three ft. and bells to around five ft. at the extremities. Near the ends of the tank, baffles are installed to reduce the slapping effect on the tank ends, as well as to approximate the natural frequency of the boat in various load conditions. This is the twelfth tank Bass has designed for Newfoundland fishboats in the 55 to 65-ft. range. Even for the regulated 65-ft. length, "Every tank is different," he explained. "I tune each for mid-load conditions." Bass adds that the tanks are favored by fishermen, not only for the speed savings, as they are maintenance-free and don't interfere with the gear when the boat is fishing. His research has shown them to reduce roll by 55 percent at all speeds compared with the flopper stoppers which range from a 45 percent reduction at cruising speed to only 25 percent at fishing speeds.