Thanks for the input.
Yes I realise that the bags are only any use when you go swimming, but
surely having a sensible distribution of bouyancy is helpful for
recovery. If you put 2 bags front and back on the same side (the RPM
has split front and back), the boat would float go on it's side when
full of water, which would be a pain to recover... same goes for
all-at-the-front or all-at-the-back options (although inherent buoyancy
should prevent the nose or stern (whichever doesn't have the bags)
sinking altogether) ? if it wasn't December, I'd go out and try it !
Given the cost of air bags, I'm going to investigate recycling plastic
milk bottles for the back. A combination of 2, 4 and 6 pint sizes
should fill the space quite nicely at the back... might rattle though.
The front will be more tricky, cause it needs to go past the foot rests
flat.
MB