Ravestein delivers another caisson to Royal Navy

Dutch steel-construction manufacturer Ravestein has delivered a new caisson to the UK Royal Navy for installation at Portsmouth Naval Base.

With the new caisson in place, the naval base has reopened the former “14” dry dock for the first time since 2002.

Reopening this dock takes the base capability up to 11 dry docks which can support ships up to the size of a Type 45 destroyer.

In October this year, Naval Base Devonport officially opened a new, 700-ton steel dock gate which was also delivered by Ravestein.

“Today is a significant moment in the regeneration of Portsmouth Naval Base,” Captain Bill Oliphant, captain of NB Portsmouth said. “14 Dock has been unavailable since 2002 so the arrival of this new caisson to give us access to this dock once again is a huge shift in capability.”

“A caisson is like a tailor made plug which fits into the end of the dry dock, forming a seal so that the dock itself can then be pumped empty of water, giving access to the underside of the ship that is in for maintenance.”

The new caisson is designed to remain in service for 25 years without the need for servicing. It also features an operating system involving electric pumps to pump out the ballast water rather than being blown out by compressed air. Routine maintenance and inspections can also be undertaken without the need to remove the caisson from service.

The caisson has already been put to the test with a full drain-down of the dry dock for maintenance crews to assess how much cleaning needs to be done to it before the first ship will be brought in for works.