Conway Maritime Press - Warship 44

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Bridgewater after the explosion of a 500-pound bomb.
Author's collection
he first trials, in May 1946, were to test the effectiveness
of 20mm cannon fire against surfaced midget
submarines. Two X-class boats were used in trials in
Aberlady Bay to the south of the Firth of Forth. They were
moored in shallow water so that they would dry out at low
tide.
Cannon Fire
The first trial was on 2 May when one craft was attacked
by two Seafires using SAP I ammunition. The first aircraft
attacked in a shallow dive and scored no hits. The second
came in from 2000 feet in a 25-degree dive. One cannon was
defective and the other only fired 69 rounds before it too
jammed. Two hits were scored both making 1/n-inch holes in
the pressure hull. The second X craft was then attacked by a
Mosquito which came in at a steep angle and fired 290 rounds
of SAP I. Four shells penetrated the pressure hull and there
were several more hits on the casing. During the second trial,
on 7 May, both aircraft fired HE I ammunition. A Seafire
attacked the first submarine scoring 22 lnits of which 17
penetrated the pressure hull. A Mosquito attacked the second
craft in a shallow dive, opening fire at about 800 yards and
breaking off at 100 yards. Eighteen hits penetrated the
pressure hull and 15 more hit the casing. It was concluded
that a surfaced X craft was a difficult target but one which
could be hit by aircraft cannon fire and which would receive
lethal damage. HE ammunition was thought to be slightly
the more effective round against such targets.
Bombs
Despite the number of ships hit by bombs during the war
there was a lack of knowledge both of the effect of bombs on
the ship and on the functioning of the bomb. In many
wartime incidents it was not possible to locate the point at
which the bomb detonated and frequently the size of the
bomb was not known. For future designs of both ships and
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