After about three hours out on the river, the standard floor in my convertible seemed very soft, but I since I didn't want to rely on just my perception, I hooked it up to my AE double-action pump. The pressure reading was close to zero. So I tried the soapy water thing - no bubbles from pinhole leaks - and then I carefully submerged it in a swimming pool - same result.
So then in my living room, I filled it to 1.2 psi, and after an hour it read 0.8 psi. To get it back to it's original fill level, it took three full (up and down) pumps on my double-action - I estimate about 10% of the number of pumps it takes to fill from empty. By the way, I was always careful to close the twist valve completely before attaching or detaching the pump to keep air from escaping.
So it seems that I can't blame the loss of pressure on leaks or temperature changes, and I'm left with thinking that my perception of the pressure loss is wrong and the gauge on the double action is inadequate for measuring such things. Any other ideas?
Floor seems to lose pressure at room temperature w/no leaks
Firstly, the pressure gauge is not 100% accurate: I think a conservative error margin of 5-10% is normal. So 1.2 could be 1.1 and 0.8 could be about 0.9.
A pressure drop of 1.2psi to 0.8 psi over 1 hr would seem to indicate a very very slow leak. Just that tiny bubble now and then in the water submerge test. I would test again, but use a small basin or similar, just to submerge the twist valve area and just watch around the twist valve.
I am inclined to suspect the twist valve. Replace it.
Have a lot of twist valves, purchased from NRS when I was trying to build an inflatable kayak some time back. Can spare you one or two. Its just 50 cents each, buying a small quantity makes no sense, the shipping cost is stupid!!
If you live in the USA or Canada, pm me with your slow mail address, if you want one.
Cheers
A pressure drop of 1.2psi to 0.8 psi over 1 hr would seem to indicate a very very slow leak. Just that tiny bubble now and then in the water submerge test. I would test again, but use a small basin or similar, just to submerge the twist valve area and just watch around the twist valve.
I am inclined to suspect the twist valve. Replace it.
Have a lot of twist valves, purchased from NRS when I was trying to build an inflatable kayak some time back. Can spare you one or two. Its just 50 cents each, buying a small quantity makes no sense, the shipping cost is stupid!!
If you live in the USA or Canada, pm me with your slow mail address, if you want one.
Cheers