• Thanks for stopping by. Logging in to a registered account will remove all generic ads. Please reach out with any questions or concerns.

Amphibious boat


Army.ca Legend
Reaction score
An interesting (if very special purpose) boat with the ability to drive itself in and out of the water:


Sealegs Amphibious Vehicle Test Drive

A new amphibious craft provides uncommon versatility without compromising on-water performance. We took it for a spin—here's how it fared on land and in the water.

August 13, 2010 10:30 AM
The tide is low, so there's a patch of thick mud some 40 yards wide standing between us and the water's edge of Massachusetts' Duxbury Bay. For most boaters, the only option is to wait for hours until the tide fills back in enough to cover the boat ramp. But not for us.

We just fire up the Sealegs amphibious craft and charge straight into the muck. By the time we're crossing the mud flats, more than a dozen curious onlookers have gathered to watch. By the look on their faces, they're impressed: The convenience of this boat isn't lost on them.

No water, no problem. This boat is an ideal way to get to the water during low tide, perfect for rescue professionals who need to access challenging terrain and more safely and efficiently transfer victims from the water to waiting ambulances. It's also just fun.

The Specs
For this test drive, we got a hold of the $113,280 Sealegs 7.1 RIB (rigid inflatable boat), which measures 23 feet 5 inches from bow to stern, with a self-bailing V-shaped hull made of 5-mm marine-grade aluminum, seven longitudinal stringers for strength and inflatable Hypalon rubber tubes lining the gunwale.

Designed and manufactured in Auckland, New Zealand, the Sealegs was first launched in 2004, but this summer is the first time the craft has been available to the U.S. market. So far, 500 boats have been produced and are being used by both recreational boaters and military and coast guard units worldwide, including the Malaysian Commando Unit, Australian State Emergency Services, New Zealand Coast Guard, Mumbai Police and the Royal Thai Navy.

On water, the craft is powered by a 150-hp Evinrude ETEC outboard motor. On land, the Sealegs gets around via three retractable hydraulic aluminum legs with 25-inch knobby tires. It's a rear-drive system (though the first AWD model will be available this summer) powered by a 24-hp, 4-stroke Honda GX670 motor stowed beneath the driver's bench seat. The Sealegs drive system accounts for approximately 330 pounds of the craft's 2690-lb. weight.

With the legs fully extended, the boat stands 7 feet 7 inches high. The front and rear legs can be lowered and raised independently, making it possible to drop just the bow or stern for easier loading and unloading of passengers. Retract the legs and wheels fully and they nest nicely against the tube and above the waterline.

Both motors are controlled from the center console, with the steering wheel capable of steering the outboard and the wheels simultaneously. Push-button controls raise and lower the hydraulic legs and wheels, and a throttle lever on the side of the console determines the RPMs of the 24-hp motor that powers the wheels. Instead of a gas pedal, the drive stick on the top of the console controls the speed and direction of travel (forward or reverse) of the hydraulic motors. But don't expect carlike performance on land. More tractor than automobile, the Sealegs tops out around 6 mph on land, and the air-cooled engine can run for only about 30 minutes at a time on land without overheating. This is not a huge barrier, since the ride is not street legal—you need to tow it to the parking lot, where you can then drive it into the water. The boat's top speed on water is a very respectable 48 mph.

Utilizing the drive system, boaters are capable of climbing and descending up to 25-degree grades of soft sand, rocks and such, enabling them to launch (and land) the boat most anywhere and reach otherwise inaccessible beaches without worry of being stranded when the tide recedes.

The Drive
Starting from a concrete parking lot in downtown Duxbury, I flick a switch on the console and the Honda engine roars to life. And I do mean roar—it sounds almost exactly like my home lawnmower. Alternating between the controls for the two rear legs and the bow leg, I trigger the hydraulics and the boat stands up to its full height. With my left hand on the wheel and the right hand on the throttle, I shift the Sealegs into gear and we roll briskly down the boat ramp.

Soon we're zipping across the mud flats. Once floating, I retract the legs, kill the hydraulic motor and fire up the 150-hp outboard. Unlike those lumbering buslike duck boats you see hauling tourists around places like New York, Boston and Seattle, the Sealegs is a decidedly high-performance ride on the water. With the wheels up and out of the way, it feels and maneuvers like most well-built RIBs. The boat gets up on-plane quickly, and the ride is smooth yet responsive.

On our way to a sand-dune peninsula called Saquish, on the east side of Duxbury Bay, we take a quick detour to drive up and over a small sandbar. The Sealegs takes it in stride. Then, as we approach Saquish, the Sealegs rep coaches me through the procedures necessary to drive up onto the sand smoothly. I do several laps, repeatedly practicing landing and launching the Sealegs.

The smoothness of my transition from sea to land and back again improves after a few repetitions, and before long, a small crowd has gathered on the beach to watch this craft do its thing.

The Bottom Line
While the Sealegs 7.1 RIB is prohibitively expensive for most, its on-water performance coupled with the ability to drive (albeit slowly) in and out of the water will prove invaluable for professional rescue operators and pleasure boaters alike.
    That was very intresting, thank you for posting this. It has a clear advantage over the only amphibious vehicle i have seen, a Argo but this seems like it would have quite a bit more speed than an Argo.
MCG said:
The Army Dive Centre has one of these trailer & LST in one: http://www.admiraldrive.com/FT2069.html

CFFSE Sea Div looked into getting one a few years ago, (mainly to resupply Betinick Island) but we couldn't get the funding. I wonder though how the salt water would effect the workings of the winch that raises and lowers the wheels.
Not exactly an amphibious boat, but a bit of "retro future" fun discovered while looking for information on some Scaled Composites aircraft:


PARLC (Power-Augmented Ram Landing Craft)

Type: experimental high-speed ship to shore vehicle

Powerplant: 2 x 900N MicroTurbo turbojets

Significant date: 1980

Built by Ames Industrial for the David Taylor Naval Ship Research and Development Center (DTNSRDC), the Power-Augmented Ram Landing Craft (PARLC) represented a new concept in marine mobility, combining surface effect ship and power-augmented-ram technology into one vehicle.

The concept was formulated early in Fiscal Year 1979, and the test craft was developed and built around 1980 by the DTNSRDC. The PARLC proved to be an attractive surface mobility concept. It was a slender barge with side walls and a movable flap on the back. It was powered by two front mounted MicroTurbo engines of 900N each that provided PAR thrust at all times. First tested in September 1980, the PARLC was capable of transiting a 100-nm distance from ship to shore at speeds in excess of 90 knots.

The PARLC was the scaled down prototype of a craft that was projected to carry 120 tons of military cargo at speeds of around 180 km/h. It was to be powered by a single 747-size CF6 engine. However, the project was cancelled by the Navy for unknown reasons. Rutan's only other known involvement with boats was the wing sail designs for the America's Cup 'Stars & Stripes'.

A different take on a "jet boat"!