Hovercraft: The Ultimate Vehicle of the Fringe
FOR MOST PEOPLE, PRACTICAL HOVERCRAFT are large water-borne vessels carrying hundreds of people across European waterways (like the English Channel) at high speeds, or Marine Corps equipment carriers that can discharge troops in vehicles the second they land on the beach (like those based at Camp Pendleton, on the coast north of San Diego County). They seem to work OK when they are big, heavily powered, and headed in a relatively straight line.
Small hovercraft, however, seem more of a science fiction kind of thing, like the little sport model Luke Skywalker drives across the desert in Star Wars (in reality an actor driving a small hovercraft). Or science fantasy, like the hovercraft made as a Saturday project, perhaps from plans that were advertised in the back of Popular Mechanics magazine, that never really seem to work as well as expected.
Small commercially made hovercraft however do exist, and they do seem to work. There are several companies in the United States making small quantities of hovercraft for commercial, recreational, and search and rescue functions, such as Hovertechnics of Eau Claire, Michigan, which has delivered over a thousand of its craft to customers since opening in 1984. Or Neoteric, of Terre Haute, Indiana, which has supplied craft of its design to the Border Patrol, and many other state and municipal agencies, and private companies. They are finding their way into their niche. And their niche is places that you can’t get to by any other means.
In the mud flats of the Great Salt Lake Desert of Utah, for example, distances are great, and surface conditions are often too soft for wheels (or even feet), and too hard for boats. Here the search and rescue team of Hill Air Force Base’s Utah Test and Training Range has two Neoteric hovercraft, used for accessing remote crash sites. Or the edge of estuaries, for example, like parts of the Sacramento River Delta, where it is too shallow for boats, and changing tides can leave vessels stranded. Here the California Department of Water Resources operates a Neoteric for fishery restoration programs.
Hovercraft are ideal for flat muddy rivers like Nebraska’s Platte, or the Connecticut River, where the Enfield, Connecticut fire department uses their Hovertechnics hovercraft for rescues on the river. Or frozen lakes and rivers, where the ice is often too thin or broken to be passable to cars, snowmobiles, or people, yet too hard for boats to break through, as in the case of the communities around Bethel, Alaska, where the United States Postal Services uses a British built Hoverwork hovercraft to make its rounds.
Other commercial applications of small hovercraft include use by environmental sampling teams, pipeline survey crews, and oil exploration. Any industry that needs to get anywhere where the roads give out, the ground is soft or liquid, and where helicopters are impractical due to expense or tree cover, could use a hovercraft. And unlike an ATV, hovercraft leave no tracks.
To a hovercraft, flowing water is static, since they float on a cushion of air. So they can travel up or down rivers with ease, and even fast moving rapids feel like frozen ground, to a hovercraft. If quarters are tight, a small hovercraft can travel slowly, navigating between, say, a rock and a fallen tree, coming to a full stop on top of a flowing stream, if necessary. It is almost as if they exist in a parallel universe, in the in-between spaces and the transitional zones between material states and seasons.
Hovercraft are a relatively recent invention. The first commercial versions appeared in England in the 1950s, where they became useful as rapid ferries. Hovercraft are ground effect vehicles that fly by pushing down on the ground (or water) with forced air. This air cushion is contained inside a flexible fabric skirt. The double walled bag skirt, which came into widespread use around 1960, made small hovercraft much more stable, channeling air through multiple individual pockets or fingers inside the skirt.
An excursion in a small hovercraft usually begins with the vessel being trailered to where it needs to be, either by an open “hover on/hover off” trailer, which slopes so one can drive directly off it, or with a regular trailer and a wheeled dolly that enables the craft to be rolled off the trailer onto the ground, or a lightweight trailer/dolly that can be removed from under the craft on arrival.
With some designs, like the Neoteric Hovertrek, one person can easily launch the vessel. This model, which retails for less than $20,000, can carry around 500 pounds, up to four people, and is available as an open cockpit, or with a windshield and a roof. It can travel safely at 35 mph, and its single two-stroke engine burns around 2-3 gallons an hour. It also has a braking system, where at the flick of a switch, scoops flip around the back of the fan, diverting some of the flow frontwards. This is unique, as for most hovercraft the only way to stop, is to back off the throttle and wait until it slows down.
To start hovering in the single engine Neoteric, the engine is turned on, and the fan on the back forces some of its air downward through a duct inside the body along the bottom rim of the craft, into vents that force the air through the segments of the skirt, and onto the ground. The vehicle quickly rises up, a sensation like a camel getting up off its knees. Once “on hover” the bottom of the craft is nine inches or so above the ground, and unless it is on a flat surface, it begins to move by gravity or by force.
Like its brethren the flat-bottomed airboats, indigenous to the swamps of Florida and Louisiana, propulsion comes from a fan on the back with rudders to force the flow of air left or right to steer the craft (though the Neoteric’s scoops further improve the maneuverability of the craft). Unlike airboats, the hovercraft’s fan is smaller, and usually encased in an aerodynamic housing. Hovercraft are also more sensitive to weight than boats. Like a motorcycle, they are steered by moving your body into a turn, as well as by their fan rudder.
Since the craft is sitting on a cushion of air, it cannot manage abrupt obstacles, like rocks, higher than the lift, which is generally less than a foot with small hovercraft. This is one of the primary limitations of hovercraft. Over water, waves much higher than a foot will catch the leading or trailing edge of the craft, causing it to drag, slow down, or stop. It is possible to flip a craft, if, moving quickly, its bow digs into the ground or water abruptly.
If a hovercraft needs to stop and switch its engines off, it will drop off its cushion of air and sit on the ground. On water, the craft is a flat bottomed boat that floats. The Neoteric’s fiberglass bottom is flat, making it very stable in boat mode. In fact, even though they move by “flying,” hovercraft are considered as boats, more than anything else, and are under the control of the Coast Guard, not the FAA. No license is required to use them.
Despite this, there seems to be a very limited recreational market, due to the fact that piloting a hovercraft is actually reasonably difficult, requiring around 15 hours or so of practice in order to be proficient. Maintenance can be expensive and time consuming (the skirts get torn up by abrasion on rough surfaces, the body is often made of lightweight fiberglass and fragile, engines need servicing by aviation mechanics, and fans get damaged by debris). There are, however, a number of clubs and associations for racing hovercraft.
Other than being unable to navigate irregular or heavily vegetated terrain, the other drawback of small hovercraft is the noise they generate. They are loud. Part of this is due to the use of two stroke engines, which are preferred for small craft as they provide more power for their weight than their four-stroke counterparts (and weight is critical to performance). Much of the noise comes from the fan blades that propel and lift the craft too. Even the mid-size twin engine craft sound like a really loud vacuum cleaner. To communicate, hovercraft passengers generally use headsets, which work remarkably well.
All in all though, small hovercraft seem to be unique in their capability to provide access to certain types of landscapes. They are opening up some of the inner corridors of the nation, the cracks between the places people normally go.