Originally Posted by boristhebold
Yes significantly, which is why its best not to inflate your tubes to a very high level in the morning if you know the weather will warm up considerably in the afternoon. especially if your not with the boat all day.
Ive seen lots of posts about pressure and the use of pressure guages, I dont use a pressure guage, I just feel if the tubes seem OK when I go out in the morning, if they feel overly hard after the air has warmed up (which doesn't happen that much in the UK) then I may let some air out if sitting in the sun.
Other than that I dont generally worry about it, my tubes are never rock hard and never overly soft so I perhaps have the right balance for the weather here. I would expect in the med for example people have to be a bit more careful.
You really *do* need to use a gauge IMHO - certainly with an airfloor SIB (not so much with RIB's) where it is critical for performance and the last 1/2 psi in the floor really makes all the difference.
As an example - we went out Saturday and anticipating the effect of the still very cold sea I went with just under 1/2 psi extra in the floor and tubes to compensate (so around 3.9 psi in the tubes). All fine and dandy and the boat performed great.
After a hour stop for lunch 3 hrs after launch and with the boat sitting in the sun I stuck the gauge on the tubes and they were approaching 5.
Sure you can ping the tubes or bend the cones etc but it's very hard to judge properly and it really is worth using a proper accurate gauge to be sure.
Originally Posted by Poly
Charles law actually...