More than 128,000 tonnes of water has been pumped out from one of Portsmouth Naval Base’s dry docks to make way for Type 23 frigate HMS St Albans.
The ship is undergoing essential repair works following her nine-month deployment – the process of which is made easier by removing all the water surrounding her in one of the 10 dry docks in Naval Base.
The water, which could fill around 1,068,333 bathtubs was slowly pumped out of the dock for over 11 hours while HMS St Albans was kept sitting central using laser alignment.
The ship is then kept upright by a series of large wooden beams that brace the ships side against the dock walls, with cranes levering them into position.
The precise process of lining the ship up is vital as all the underwater equipment located on an antisubmarine frigate, including her sonar dome, only have 50cm clearance to the dock bottom once all the water has been drained.
Maintenance works will include repairs to her underwater fittings and works to her rudders, including painting them, to ensure they are preserved until the next planned maintenance period.
The frigate will be in the dry dock for several weeks before the water will be allowed back in and she will return to sea.
Deputy Marine Engineering Officer Lieutenant Peter Ainscow said: “Getting into dry dock is a lengthy process but it is essential to carry out essential underwater maintenance that otherwise would be expensive or impractical to be completed in the water by divers or in a habitat.
“All ships incur wear and tear from deployments and HMS St Albans in particular has been operating at a high operational tempo which makes this sort of work necessary for her continued capability.”
Dry Docks have been used since the 10th century to allow for maintenance, repair works and construction of ships. Portsmouth Naval base also still has the oldest surviving dry dock commissioned by Henry VII in 1495. This dock currently holds the world’s oldest commissioned Warship, HMS Victory.