The miniature torpedo was based on the limpet used by British commandos, since the limpet was about 10 lbs and measured 10" x 5" x 5 " one can imagine that a small motor was adapted so that it must have weighed about 12-15 lbs.
Maximum range was 400 yds but since it was not long enough to be properly aimed, Wilson decided that he should close to 100 yds to launch it to be able to hit a target about 300 feet long. Detonation was by contact instead of using the delay fuse and magnet was not necessary as in the original limpet.
It was not a great success as the operators launching them from their folbot had only about one minute before the explosion occurred. The standard limpet was more practical as it could use fuse delays of 1 hour and even more, giving the operators sufficient time to make good their escape.
Wilson and Hughes carried with them four miniature torpedoes but managed to launch only one as they heard shots and believed themselves to be discovered. The miniature torpedo did not explode. The fact that they did not return to the submarine proved that the experiment had not be a success and I do not think it was repeated.

Platon Alexiades