As early as 1939 ships plying the East Coast were convoyed to reduce losses. The East Coast convoy route was a mile wide and extended from the Firth of Forth to the Thames and was protected by the Royal Navy.
The principal dangers were from mines and E-boats. Owing to danger of attack, the fishing industry was suspended for the duration of the war. This did not mean the fishing fleet was moth-balled however, as many of the fishing boats were converted to minesweepers to protect the East Coast convoys. Typically, many of the fishermen volunteered for the Royal Naval Reserve and went hunting for an altogether different prey, a much deadlier prey. As well as minesweepers, Great Yarmouth, which had now become H.M.S. Watchful, was protecting the convoys with Air Sea Rescue boats, salvage tugs and M.T.B.s.
In 1940 HMS Miranda was established at Fishwharf and became home to the minesweeping trawlers and sundry vessels. It took until 1944 before purpose built minesweepers had replaced the minesweeping trawlers. The Air Sea Rescue service was a joint operation performed by the R.N., R.A.F. and R.N.L.I. and accreditted with the rescue of 800 airman during the war they could feel justly proud of the part they played.