Yes it is on grass but the tyres are on paving slabs. Tyres don't like to be left on grass too long
I agree, tyres don't like to be left on grass for too long and they don't like to be left in one place for too long either, they tend to get flat spots. If you want to be ultra cool, buy some cheap axle stands, jack up the trailer and pop the stands underneath. Keep the tyres off the ground and they'll be ok.
The reason I asked about grass is, in a similar way in which washing dries better on concrete rather than on a lawn, your boat being covered by a waterproof material, will in effect keep moisture in as well. My little boat has been kept in a barn for a number of years and is completely dry except that the base is thin layer of gravel covered soil. Every Winter the hull which is covered by a loose Tarpaulin, thrown over, not tied down and is there to keep the dust and leaves out. However, during wet weather, invariably the hull is covered with moisture. I use the moisture traps we have spoken about, but placing another old Tarp on the floor stops this happening. The air flow through has kept it very dry and no need for heating.
