As my hon. Friend said, HM Submarine Affray was an A-class submarine completed in 1946. The class had originally been designed for operations in the far east during the latter part of the second world war. The submarine used a diesel-electric power plant, with diesel engines being used for surface propulsion and charging of the batteries. The batteries powered electric motors for underwater propulsion.
Some time after completion, Affray was fitted with a snort mast. That was a tube whose head was above water permitting the submarine to run its diesel engines while at periscope depth, reducing the chances of it being detected by surface ships or from the air.
The submarine was scheduled to carry out a series of exercises. She was scheduled to make a surfacing report by radio at 1000 hours on
Some weeks later, the wreck was detected and identified north of the Channel islands, lying in 260 ft of water. In the succeeding months, the diving tender HMS Reclaim dived on the wreck in an attempt to discover the reasons for her loss. One of the discoveries made was that the Affray's snort mast had broken off and that that might be connected to her loss.
A board of inquiry was convened under the presidency of Rear-Admiral R. M. Dick. It presented its interim finding to the Commander-in-Chief, Portsmouth, Admiral Sir Arthur Power, on
The board considered a number of possible causes for the loss, including battery explosion, material failures, operating errors, mines and collision. Of these, material failure was considered the most likely immediate cause.
The board of inquiry therefore concluded, with the reservation that
"certain technical evidence and calculations will need further checking", that the submarine was lost due to the sudden snapping of the snort mast. It determined that that was caused by a material failure resulting from the mast's brittle condition, that the submarine was overwhelmed by the resultant rapid flooding, and that death would have come very quickly to the crew.
The Board of Admiralty signalled the Commander-in-Chief, Portsmouth, on