As the dredger’s grab had cracked the bomb-case open, and it was still live, naval bomb disposal experts were sent on board to defuse it.
The drama began as the dredger, Clyde Bay, was deepening the harbour bed off Albert Johnson Quay.
The bomb – 3ft long and a foot across – was jammed in one of the dredger’s grabs – and the crew left it exactly where it was.
Portsmouth and Medway clearance diving team’s bomb disposal experts, led by Lieut D Ellis, were called in.
They defused the bomb after two hours.
‘This was certainly a German bomb dropped during World War II,’ said a naval spokesman.