Actually i was considering doing just that, sanding it back and applying a thing layer of glass before repainting, as i know the ply wood likes to "breathe". Is there however any potential downside/danger to glassing one area of the boat and restricting its ability to expand/contract whilst the rest of the boat is still free to do so, particularly at the junction between where the glass ends and meets the ply that is free to expand/contract? Also where is a good place to get the painting supplies from? Bunnings ok? or will i need to go somewhere more tailored for boating like bias boating or a chandler?