Not that it is off a half inch but there are difference from where the hull weight presses down from g-forces on the trailer during rough road rides, etc. Even a tiny amount of irregularity in the hull could result in a wear area if the outer, horizontal supports (they are horizontal with the ground is what I was implying, and the hull is horizontal as well) albeit the boards are turned up vertically for max support. Thats what I was saying. The gel coat wear is from an area of the hull hitting the boards, that simple. If we could get solid contact all the way we wouldn't have any issue. I've not lost any gelcoat but I have watched mine trailer bunks pretty close. I've seen the damage that bad adjustments and contact can cause though.