Re: Using poly and epoxy resin together?
If polyesters didn't bond well to polyesters then all boats would fall apart. In production all boats have poly to poly bonds, the longer it sits and cures the better surface prep is needed, in the first 24 to 48 hours little or no prep is needed, after that then sanding is advised, after many years, as in this case, you need to grind it well with 36 grit or so. <br />You need to look at what failed in the boat, was it the polyester resin, or was it the wood. If it was just the wood that failed, then whatever they did in the begining worked until the wood got wet and rotted.<br />Now for the epoxy crowd, epoxy is much stronger, bonds better to most things, is a much better glue and is more water resistant, but it's not a miracle cure. It won't stop the wood from rotting if it gets wet, it won't make the repair last longer, and in the small amounts used it won't make your boat faster by being lighter. To take advantage of what epoxy can do, the part needs to be well engineered and fibers other than glass need to be used.<br /><br />I'm not saying epoxy is bad, if you like it and want to use it, it's fine, but don't think you if you don't use it the repairs will fail. <br /><br />Another thing, most of the polyester resin you buy at any store is better than what the main resin base used in production boats is. The main base resin (DCPD, most are blends of it) used to make boats has a very short shelf life, if it's not used right away it will get hard. They need to use a better grade of resin to get the shelf life needed for over the counter products.<br /><br />With epoxies it can be the opposite, to keep the cost down and because of health concerns, some over the counter products are not as good as what might be used in a production application.
