The DDH provides a controlled environment for ship and submarine assembly, and avoids the difficulties caused by building on the slope of traditional slipways. Outside the hall, a 24,300 tonne capacity shiplift allows completed vessels to be lowered into the water independently of the tide. Vessels can also be lifted out of the water and transferred to the hall. The first use of the DDH was for construction of the s, and later vessels of the were also built there. The shipyard is currently constructing the s, the first of which was launched on 8 June 2007. BAE Systems is currently studying the design of a new class of ballistic missile submarines. BAE Systems also has orders for submarine pressure domes for the Spanish Navy.