Not to pour water on this endeavour, but might I suggest that anyone embarking on this or a similar venture read the following book:
'The Frogmen: The Story of the Wartime Underwater Operators'
by Waldron & Gleeson
The very birth of the use of reberathers by the Royal Navy. Apart from being a true and highly readable story, it details the designs, misfires, mistakes and the high loss-rate of 'frogmen' who were used, to some degree at least, as guinea pigs for a
then new (but needed) concept in diving.
Good luck Digger - just be careful
