In a recent demonstration carried out during RIMPAC 2014, the US Marines displayed and tested a fully-functional, half-scale prototype of its new amphibious transport vehicle. In its proposed full-size version the Ultra Heavy-Lift Amphibious Connecter (UHAC) concept is designed to power across the water with a payload of nearly 200 tons (180 tonne) at up to 20 knots (23 mph/37 km/h) and be capable of driving up on to the shore and over the top of obstructions up to 10 ft (3 m) high.

As the proposed next generation of amphibious lander, the full-scale version of the UHAC is set to boast triple the carrying capacity of the Landing Craft Air Cushion (LCAC) vehicles currently used to provide ship-to-shore transport for the US Navy by offering a payload capacity of up to 190 tons (172 tonne). Even though the demonstrator is just a half-scale version, it is still a substantial vehicle in itself at 42 ft (13 m) long, 26 ft (8 m) wide, and 17 ft (5 m) high.

Developed from its previous incarnation as a one-third scale Captive Air Amphibious Transporter (CAAT) concept, the land-sea capability of the UHAC is provided buy a set of tracks – similar to a tank – fitted with captured-air foam cells that provide buoyancy, act as paddles when in the water, and behave as track-driven pads when on the land. This system provides a very low ground pressure footprint that helps make the UHAC truly amphibious, at it is also able to traverse through mud, sand and marshland equally well.

The RIMPAC demonstration involved the UHAC leaving the Marine Corps Training Area Bellows and traversing the ocean to the USS Rushmore, where it entered the ship’s amphibious landing dock (or well deck), picked up an assault vehicle, and successfully transported it back to the shore.

"Showcasing the UHAC during RIMPAC is a big deal," said Dave George, project officer at the Marine Corps Warfighting Lab. "This is a great way to let people know that this new technology is being developed and this is a great way to show what it can do. Today went quite well. We had much better seas then we anticipated and we were still able to get onto the well deck of the USS Rushmore."

The next stage of the UHAC's development remains unclear at present and no mention has been made of taking the final steps necessary to produce a full-scale version. But given the apparent success of the RIMPAC demonstration and the obvious advantages of the captured-air foam cell track design, it is likely that we may well see more developments on this vehicle in the not too distant future.

Originally created by Navatek Ltd – a hydrodynamic research and naval architecture company based in Honolulu – the project was funded and carried out by the Office of Naval Research (ONR).

RIMPAC (Rim of the Pacific) is the world's largest international maritime warfare exercise and runs from June to July every two years. It takes place in and around the Hawaiian Islands with the US inviting military forces from the Pacific Rim and beyond to participate.

The short video below shows the UHAC in action.

Source: US Navy

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