Air Support
Hovercraft will carry passengers and vehicles between remote Alaska towns.
By Bruce Buls, Technical Editor   
“Think of it as an air-hockey table turned upside down,” said Keith Whittemore, president of Kvichak Marine
Industries, during an interview with a Seattle TV station.
Whittemore was standing on the well deck of the Suna-X, a 93'¥44' hovercraft built to carry up to 49 passengers, an ambulance or other vehicles, and cargo between two remote Alaska towns. Whittemore had persuaded the city of Seattle to allow him to run the new hovercraft up on a public beach for a local dog-and-pony show before sending it up north. (Some mothers and their children probably got more excitement then they expected when the big blue-and-white craft came roaring up not far from their beach blankets.)
Known best for their fast aluminum boats, Kvichak is making inroads into the hovercraft market, the current project being its second. The first was a smaller, single-prop hovercraft built for Crowley Marine’s operations in Prudhoe Bay, Alaska.
“We aren’t sure what to call them,” said Jennifer Rose, Kvichak’s marketing manager. “They aren’t really boats, even though they float. I think we’ve settled on ‘craft.’ ”
“These are wonderful things,” said Whittemore, “but they have very specific uses. If you can use a boat, that’s best. But if there’s not enough water or if it’s a sensitive area that can’t be dredged or have adequate docks, pilings or other large infrastructure, then hovercrafts are the answer.”
The new $9 million craft was designed by Hoverwork Ltd., a hovercraft manufacturing company and operator based on the Isle of Wight in the United Kingdom. Hoverwork designed and built several hovercrafts for the Canadian Coast Guard that are now stationed near Vancouver, British Columbia.
John McGrath, the Suna-X project manager for the Aleutians East Borough, the craft’s owners, recently retired from the Canadian Coast Guard where he worked extensively with the agency’s hovercraft. His new company, Seamasters, specializes in the design, construction and operations of the high-speed, amphibious vessels.
“The Alaskans came to the Canadian Coast Guard when they started considering hovercraft, and they liked what they saw,” said McGrath. “So we helped develop this one for them.”
For more than two decades, the people of King Cove, Alaska, have been looking for a way to get from their isolated fishing village on the southeast end of Cold Bay on the Alaska Peninsula to the all-weather airport in the city of Cold Bay at the northwest end, mostly for emergency medevacs. The preferred solution has been by road, but environmental concerns have precluded that option for the time being. The compromise is a new, 17-mile road partway up the east side of Cold Bay to a hovercraft landing area. From there, the Suna-X will run across the north end of Cold Bay to a spot near the airport, which features a 10,000' landing strip. The trip across the north end of Cold Bay is about nine miles and should take about 15 minutes with the hovercraft running at 40-45 knots.
While both King Cove and Cold Bay have docks, running boats between them is often difficult if not impossible because of weather, especially during the winter. “There is no protective harbor in Cold Bay,” said Stanley Mack with the Aleutians East Borough. “And King Cove is directly exposed to the North Pacific Ocean. The area that the hovercraft will be operating in is not exposed to the outside.”
“This is the perfect application for a hovercraft,” said McGrath. “It’s an environmentally sensitive area where you really only have two choices: hovercraft or helicopter.” And like a helicopter, a hovercraft can be parked anywhere since it travels over land and water. But unlike a helicopter, you can drive a large truck or an ambulance on and off this craft.
The Suna-X is powered by two sets of Detroit Diesel/MTU engines. A pair of 16V2000s, each rated at 1,200 hp, turns two 5-bladed controllable-pitch compressed-wood propellers that measure 11'6" in diameter. The propellers are housed in aerodynamic ducts. The other engines are 12V2000s, each rated at 900 hp, that power the four squirrel-cage fans in the cushion lift system. The 12V2000s also turn two separate fans that push air through the swiveling thruster nozzles located on each side of the forward cargo deck. All engines are mounted on vibration isolators.
The welded aluminum hull is essentially a flat-bottomed raft with a semicircular bow. The nearly vertical sides incline slightly at the upper edge where the neoprene rubber coated, woven nylon skirt is attached. The flexible skirt, which measures 1.5m (4.92') deep at the stern and 1.8m (5.91') at the bow, forms a virtual seal between the hull and the surface below. The skirt allows the craft to pass over irregular surfaces, including waves up to about 6'6".
The ability to travel over water, mud flats, marshes and relatively flat land is one of the great selling points of hovercrafts. The air pressure under the hull of the Suna-X is only 50-lbs./sq. ft., which makes it ideal for environmentally sensitive areas.
Another environmental consideration was noise. While some hovercraft are powered by gas-turbine engines, the Suna-X uses quieter diesels. The craft’s noise signature is also reduced by the use of two large-diameter slow-speed propellers. The noise level at 1,000' is about 65 dBA.
Noise levels inside the heavily insulated passenger cabin haven’t been measured, but passengers could have normal conversations while running at about 40 knots during the demonstration rides in Seattle. Double-glazed windows from Garibaldi Glass, Burnaby, British Columbia, also reduce noise, retain heat and eliminate fogging.
The cabin is equipped with 47 seats and space for two wheelchairs.
A ladder in the center of the passenger cabin provides access to the small pilothouse or “control cabin” above. Two operators — a captain on the starboard side and a radar operator on the port side — sit in a pair of seats facing the instrument panels over and under the forward windows.
Steering is accomplished by controlling the three rudders mounted to the rear of each propeller duct. The captain moves the hydraulically operated rudders by means of a foot-operated rudder bar. The bow thrusters provide both yawing moments and side force, and are used primarily for low-speed maneuvering. The thrusters are also used for going in reverse and as air brakes.
McGrath said he will provide the Alaskan operators with 100 hours of hands-on training. He will also help supervise the construction of concrete landing ramps.
“The people in King Cove have been waiting for something like this for over 10 years,” said McGrath. “This is also the first commercial hovercraft that will regularly carry passengers. There’s a sister ship being built in England that will carry 130 passengers, but this is the first of its kind.”