puzzled about leaky toob

[BogMonster]

Originally Posted by codprawn

You aren't filling it with warm air at the hottest time of the day are you? Bet it's not that warm anyway but could it be expansion/contraction rather than a leak?

The thermal expansion is quite noticeable but that wouldn't explain why one chamber was still nice and firm last night (rear one on one side) but the other 3 were somewhat flaccid (I didn't actually look at the bow chamber as I was too busy stomping around and muttering!).

If I have got 3 leaky chambers I will be well *****d off! Perils of buying an inflatable boat I suppose...

[jyasaki]

Hypothetical situation:

4 chambers in line (a multi-chambered tube straightened out.) Movable (pressure equalizing) baffles between each attached pairs of chambers.

Fill the left most chamber full (operating pressure.) Fill the second chamber to 75%. Fill the third chamber to 75%. Fill the right-most chamber to operating pressure (which will also bring 2 and 3 up to operating pressure as the baffles migrate into the partially filled chambers.)

Now, there's a leak in, say, Chamber 4 (the last one filled.) As the pressure drops in Chamber 4, the baffles will flop towards the lower pressure side, which will cause an apparent decrease in pressure in Chambers 2 and 3.

Chamber 1 will not be affected, as it was filled to a volume of the chamber plus the baffle at the outset.

Bottom line is that the inflation procedure will have an effect on how a pressure loss in one chamber is presented when looking at the whole boat.

If your full chamber is in the middle, well, I guess I have no explanation.

jky

[BogMonster]

Today there is just the one (port side rear chamber) right down again, the others seem OK though one is still harder than the others and it is the one furthest away (stbd side rear).

I don't know how much "give" there is in the baffles but surely even if there is 3-4 inches movement, the volume of air displaced by the moving baffle will be relatively small compared to the volume of 6 feet of tube so the pressure change will only be a little bit?

I have pumped it up hard (again) and advised it in a stern voice that I will be looking for the leak with a chainsaw if it doesn't stop messing me around

back after work for another look...