Sweeping the shipping lanes free from the deadly menace of enemy mines was the constant and hazardous task carried out in all weathers, and often in face of air attack, by H.M. Minesweeping trawlers, of which the one seen in this drawing was typical. Various kinds of mines had to be dealt with, including the moored variety (see small diagram), which was held at a pre-determined depth under the seas surface by a cable attached to a sinker resting on the sea bed. The minesweeper had to cut this cable so that the mine floated to the surface, where it could be destroyed by gunfire. To sever the cable the minesweeper trawler wound out from a winch a serrated sweep wire, to one end of which was attached the buoyant flagged Oropesa float and the otter control, these held the sweep wire out on the trawlers quarter at the correct distance and depth; at the inboard end of the sweep wire a box-shaped “kite” kept it down. The trawlers gun crew (A) fire the 12-pounder gun at mines which had just been swept to the surface. At the winch (B) enginemen control the sweep wire. The small wheelhouse (C) and look-out platforms on which are mounted twin Lewis guns (D) The skippers bridge (E). The trawlers crew handling the Oropesa float (F).