During the next few days Roberts and Laidlaw began to develop a replacement tactic, which involved exploiting the U-boat captain’s natural caution by tricking him into ordering his vessel to dive to avoid an escort moving into potential spotting distance. Hearing the escort pass by and believing that he had not been seen, the submerged U-boat would then move to what it assumed was a safer location. Wargames and experience suggested this would be a slow turn designed to place the U-boat in a position parallel to the convoy while
