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Old 11-03-2009
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I doubt that Hinckley, Morris or other premium builders put ply under the mast step. Cost really isn't a factor for these builders - quality is. I suggested using multiple layers of biax. Not all at once. Even if you wait until one layer is hard it's easy to wash the amine off with a nylon pad and some water. Exotherm is not an issue if done this way. West epoxy is usable down to 35 degrees f. At these cold temps exotherm is less of an issue. Plywood does have more compression strength than solid wood - of the same species. Fir or mahogany plywood still compresses and under a mast fully rigged it will eventually happen. If any moisture gets in it will deteriorate and that's where we started. As far as core material where core should be used, balsa is far superior in several ways than plywood. Less chance of moisture travelling with end grain balsa, less weight with balsa where the weight is not an advantage, and better bonding to curved surfaces with balsa than with plywood. The following is taken from West's fibreglass repair manual which is free on line here.http://westsystem.com/ss/assets/HowT...aintenance.pdf
Brian
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