I read that Grumman aluminum canoes have flotation tanks built in and won’t sink by itself (assuming no additional attached weight when tipped over)? I would like to hear comments from those who have tried to sink an aluminum canoe, or at least those who have good knowledge about aluminum canoes.
Please do not assume aluminum canoes are heavy and will sink by themselves, as many plastic canoes are much heavier for the same size.
My (used) 17’ standard version (at around 75 lbs) does seem to have intact flotation tanks at both ends, though I have not opened them to check (if previous owners removed flotation). Should I open them to check though? Is Grumman’s flotation provided by foam or air? I do see some microscopic holes around the tanks, but nothing obvious.
I read from the following thread that if flotation tank is filled only with air and tank has a major hole, then the canoe (not sure if that canoe was a Grumman though) can be sunk:
I can easily DIY additional flotation with sealed gallon-sized water bottles. 8 bottles can easily fit in the 17’, with each one providing 8.35 lbs of flotation (8 bottles would provide 67 lbs of flotation, if I calculated it correctly). Those bottles can be noisy though and take up space. So I prefer not to add them, unless necessary. How many should I add, if I should add any?
Our Grumman won’t have any additional weight attached, when it is tipped over (all weight on it will fall into water). We do not paddle in heavy rains. Total additional weight (people + gears + food/water) should be always under 450 lbs.