Yeah, for the deck, I am thinking it may be worth saving a few bucks and quite a bit of weight and go with the plascore. From what I can find on the internet, it will do the job well. A lot of high end boat manufacturers seem to use it and nida core board for decks. It is not as strong as coosa, but if finished properly it appears to me that it will work great and have the wieght advantage. That is my thinking for now unless someone has a strong opinion the other way.
