Just to return to the swimming for non-swimmers for a sec if I may.
My dad was a Flight Engineer on Halifax III's, returning from Canada in 1943 and ending up on 158 Sqn (he did a number of ops on the famous Friday the 13th). As a F/E it would be his job to assist the dinghy out of the wing if the aircraft ditched. Unfortunatley he swam like a brick so he managed to persuade the PE instructor that he would do a width of the pool at St Athan instead of a length. He then proceeded to open every door along a corridor opened onto the pool, sprinted down the corridor, leapt as far across the pool as he could and beat the water into submission to get to the other side!
He had a nice cushy number as an airframe mechanic in Canada working on Ansons and Oxfords in a Nav School before deciding that bomber ops were the way forward. Luckily he survived 36 ops before transferring to Stirling V's after VE-Day flying to Mauripur (Karachi) from Stradishall via Stoney Cross - Tripoli - Lydda (Israel) - Iraq (Habbaniya). Although he was a regular having joined in early 1939 and a Flying Officer by this point he then decided to become a teacher and never flew again until going on holiday to Spain in the early 1970's.