Then, in the early evening, Duncan picked up a U-boat close on the port bow. He made chase, ordering Tay to make a parallel search to port. Forty minutes later Duncan’s bridge spotted a telltale cloud of spray, where the waves had struck a U-boat conning tower. As Duncan approached, the U-boat dived. After dropping a pattern of ten depth charges, Gretton and Robert Sherwood, captain of Tay, executed the first WATU operation of the journey, Observant, a search of the area in a square shape, each ‘side’ two miles long, with the U-boat
