The 500 pound World War Two device was picked up during dredging work.
HMS Victory Restoration Hits New Phase
Restoration of Nelson's flagship, HMS Victory, has entered a new phase, with the removal of the final mast.
The mizzen top mast was taken down by contractors overseeing the work as the ship's three masts, bowsprit and rigging have all been dismantled over the summer at her home in Portsmouth's Historic Dockyard.
The last time HMS Victory was seen without her top masts was back in 1944.
Director general of the National Museum of the Royal Navy, Professor Dominic Tweddle said:
"Watching the team painstakingly disassemble the rigging and masts of HMS Victory has been heart stopping at times. To do this intricate work, while still keeping Victory open to the public, has been a logistical masterpiece."
Most of the highly skilled operation on the ship, which was built in 1759, has been carried out by master shipwrights and other specialist staff employed by BAE Systems.
John O'Sullivan, BAE Systems project manager for HMS Victory, said: "We have removed the upper sections of all three masts and bowsprit, booms, yards and spars, including 26 miles of associated rigging and 768 wooden blocks, some of which are 100 years old. We will then catalogue and document everything for future surveying, design and replacement.
"When the rigging is replaced a decision will be made as to whether the wooden rope blocks can be re-used, recycled or replaced. Our team will carefully manage this major restoration project, keeping disruption to a minimum."
Restoration work on HMS Victory, which was Nelson's flagship at the Battle of Trafalgar in 1805 where the Royal Navy beat a combined French and Spanish fleet, will continue over the next ten years.
640 men were killed when the South African troop carrier was hit by a cargo ship in 1917.
The 79-year-old man suffered a serious head injury in the Cranmer Road car park in Winton.
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