The huge curve of her transom was rolling on top of Icarus' jack-staff - and then the frigate was shuddering and pounding to the colossal astern power.

Questions of fire hazard, outer cover defects, gasbag and gas valve leakage, servo motors, structural overweight, astern power, and engine defects were never referred to these two professors, who had no knowledge or experience that would have enabled them to express an opinion on such matters.

During her trials off the west coast of Scotland in 1989, Upholder lost power when her propulsion control system failed to cope with a sudden switch from full ahead to full astern power, a problem which contributed seven months to the three-year delay in her becoming operational.