“I’ve been on this hull in San Francisco, New Zealand and Fiji,” says Alex Brodie of Channel Island Cruises
in Ventura, Calif., of the extensive research that went into the company’s selection of the Teknicraft catamaran design for their new build, “And what appealed to me was the hull’s combination of sea-keeping at speed.”
Brodie’s company, which has a transportation concession for the Channel Islands National Park, currently operates four single-hull 49-passenger boats. The new 149-passenger 65- x 24-ft. Cummins-powered catamaran Islander, delivered in mid March, will replace two of the smaller vessels. The new vessel features a range of environmentally friendly features such as high boxes around the fuel filler fittings to catch overspill. It also has non-toxic high polish bottom paint.
Aluminum boat builder
All American Marine, of Bellingham, Wash., has a partnership with Auckland, New Zealand’s naval architect Nic de Waal for the exclusive building rights to his unique Teknicraft catamaran designs on the U.S. west coast. Each of the twin Teknicraft hulls or sponsons employs a combination of symmetrical and asymmetrical shapes. The symmetrical bow-sections ensure directional stability in short swell conditions and following seas, while the asymmetrical amidships and aft sections ensures softness of ride and reduced wetted area which enhances comfort and economy. Horizontal steps on the inside of the tunnel walls act both as chines to deflect green water from
the hull surface, and to break up the solid water into spray.
A hydrofoil system is fitted to the hull of the Islander. The lift produced by the foil-system reduces the hull resistance, which increases speed; while at the same time increases the load-bearing capability. The foil action reduces the power needed to maintain service speed. Unlike conventional hydrofoils, which lift the hull completely out of the water, these foils are designed to only partly reduce the draft, thereby reducing resistance, but still maintaining good sea-keeping by having the hull still partly submerged.
The boat is powered by a pair of emission compliant Cummins KTA19 M4 engines each delivering 700 hp @ 2,100 rpm into Twin Disc MG 5114A SC marine gears with 2.5:1 ratios and turning 5-blade 36- x 42-in. Osborne propellers on three-in. Aquamet shafts. Brodie explains the choice of Cummins engines as a combination of factors including their proven record in the demanding crew boat environment and their ability to meet the power to weight ratio needs of this project. He also points out that his firm has repowered one of their existing single hulled boats with a Cummins engine under California’s Carl Moyer clean air environmental program. Speeds on sea trails peaked at 27 knots and provided a comfortable cruising speed of 24 knots at about 2,000 rpm, “Just as predicted,” said a pleased Capt. Brodie.
Hull plating is 1/4-inch 5083 aluminum below the water line with 3/16 and 5/32 above. All metal was cut in Seattle at Northwest Plasma.