Originally Posted by benhben
The tubes inflated to 0.25bar on the pump usually read about 0.2 bar and the air floor at 0.8bar is usually about 0.5 bar on the gauge.
The tubes feel ok but i tend to have to overinflate the floor abit. It doesn't affect the boat performance that much
So you're losing 20% of your positive pressure on the main tubes, and a bit more on the keel, which is the bit that is most exposed to the cold water.
I say 20% of your "positive pressure". However, you have to allow for the fact that when your pump shows 0.25 bar, there is enough air in the tube to fill it 1.25 times. All of that air is shrinking until there is only enough to fill it 1.2 times. The contraction is therefore about 4% which is well within the bounds of the effects of a temperature change.
Worry not. Inflatables are surprisingly robust. Unless you're after ultimate performance or going into extreme conditions, the boat will cope happily with this sort of variation. The pressure will vary that much on a summer's day.