Re: HSE advises against the use of Octopus rigs.

I should think they do advise against using an octopus in an emergency. An
independent air supply is clearly preferable. Also if you double the breathing
rate - plus extra for panic - you more than double the chance that the reg will
freeflow due to icing. I expect a fair number of people are now dead because of
this last effect (deepish dive, attempted air share in a panicky situation,
sudden huge outflow of bubbles... would you make it to the surface?). I reckon 2
independent tanks ought to be the minimum below about 70 feet/20 meters.
Especially in cold water.

Cheers,

Charles.