Heavy Replenishment At Sea Project, HMS Raleigh.

Engineering the Ministry of Defence at sea.

The replenishment of Royal Navy ships at sea is critical to the operation of a modern, flexible navy. Presently, the Royal Navy vessels are limited to two-tonne ship-to-ship transfers, however, this constrains replenishment at sea, particularly with modern equipment. The Ministry of Defence (MoD) commissioned the Heavy Replenishment at Sea (HRAS) project. It was undertaken by Rolls-Royce, which developed the next-generation technology, permitting five-tonne transfers, even in heavy seas.

Replicated conditions.

Before this HRAS technology could be fitted to the new Type 45 Destroyers, the MoD required Rolls-Royce to demonstrate it functioning on land. Once the technology was successfully demonstrated and accepted, the installation was converted for the training of all Royal Navy personnel. The HRAS demonstrator was constructed at HMS Raleigh, the Royal Navy’s modern training facility at Torpoint, Cornwall, and we were appointed to provide the MEP services design with acoustic support.

Powerful transfer.

To faithfully replicate the conditions at sea, a hydraulic ram was built to simulate various sea states. It became apparent during concept design that the power requirements of the hydraulic ram combined with the main winches and ancillary loads would require more than 3MW of power. However, this power requirement would swing between consuming 3MW of electricity to generating 1.5MW within a fraction of a second. If the site was connected to the grid, such power fluctuations would make lights of the surrounding town flicker. We embraced the challenge.

Our solution involved bringing in an external generator farm that could produce the vast amounts of power required, plus load bank to absorb most of the generated power. This allowed Rolls-Royce to successfully replicate heavy sea conditions needed to prove the technology functioned correctly and safely.