Austal will build the fourth and fifth joint high-speed vessels (JHSV) for the US Navy under a $204.6m contract awarded by the US Department of Defense.

The JHSV features a flight deck for helos and a slewing vehicle ramp on the starboard quarter that facilitates the use of austere piers and quay walls.

The 103m vessel can transport medium-sized operational units with their vehicles, or reconfigure to provide troop transport for an infantry battalion.

The joint-use platform operated boat will also be capable of supporting humanitarian relief efforts.

Operating in shallow waters of under 4m, the ship can reach speeds in excess of 35kt when fully loaded.

The contract is part of an existing ten-vessel $1.6bn programme.

Austal, the principal contractor, was awarded the first ship contract in 2008, with options for nine extra vessels expected to be exercised between 2009 and 2013.