Nothing anyone else said was wrong, in my opinion. WoodenBoat did a review of all boatbuilding glues a few years ago and found that PU isn't really the best glue for water use. They also found that epoxy wasn't the best, so these were really the highest standards imagineable. Resorcinol is supposedly the best, but I rarely see it, and I don't think it is necessary for anything we might touch. I see no real advantage to PU for most of what we do except for bondong any exotic woods, where PU really excels. It can bond anything from oily teak to ebony and even the really wierd ones, like oak. Just what I've learned, and I still almost always use epoxy or plain woodglue.