HMS H29 and the cost of an unclear order

During 1926 basin trials at Devonport, H29 needed to settle far enough to submerge her torpedo tubes. The first lieutenant said that he intended to put only a little water into the main ballast tanks, but his words were understood as an order to flood them. Shore cables and lines obstructed open hatches as the stern submerged, and water entered too quickly for the tanks to be blown clear. One rating and five dockyard workers died. The courts martial faulted unclear orders and failures of supervision while clearing the petty officer who believed he had obeyed the instruction given. The episode shows how ambiguous command and temporary dockyard conditions can combine into a fatal accident.