coosa board

[6buoys]

rebuilding a 72 20 sf want to put a bracket on and thinking about coosa for floors and transom and what thickness to use for each

[bly]

The blue water 26 is 30% lighter then wood and the bluewater 20 is 45% lighter. One layer of 1208 or 1708 is all that is needed on top. On a replacement transom changing over to a full transom with a bracket I would use two 3/4 pieces with a layer of glass in between as well as on inside and out with 2 layers of 1708 on a 23 sea craft. I prefer Vinylester resin but polyester is more then OK. Epoxy is a waste of money and a lot more time curing. On a 20 ft boat 2 sheets of 1/2 should be good with the same glass laminate. The reason for smaller core on 20 is the engine options and the smaller lighter boat being pushed. Also the new raised floor will also support the new transom in a higher and much better way then the old wells. One thing to remember is! Transoms never fail or flex until it gets wet. Then the wood softens and looses its structure. Most old boat floors use small scraps of junk plywood in and did not fail or flex until water got to it. So blue water 20 is way better and will not fail or weaken if water was to get to it. The 26 is a lot more money and is not usually stocked. Just remember it will not hold screws near as good as wood. I usually mount all my hatch hinges once near finish. Then remove screws. drill out holes much bigger and make a thickened putty from epoxy or even vinylester resin.

[martin]

Originally Posted by bly

The blue water 26 is 30% lighter then wood and the bluewater 20 is 45% lighter. One layer of 1208 or 1708 is all that is needed on top. On a replacement transom changing over to a full transom with a bracket I would use two 3/4 pieces with a layer of glass in between as well as on inside and out with 2 layers of 1708 on a 23 sea craft. I prefer Vinylester resin but polyester is more then OK. Epoxy is a waste of money and a lot more time curing. On a 20 ft boat 2 sheets of 1/2 should be good with the same glass laminate. The reason for smaller core on 20 is the engine options and the smaller lighter boat being pushed. Also the new raised floor will also support the new transom in a higher and much better way then the old wells. One thing to remember is! Transoms never fail or flex until it gets wet. Then the wood softens and looses its structure. Most old boat floors use small scraps of junk plywood in and did not fail or flex until water got to it. So blue water 20 is way better and will not fail or weaken if water was to get to it. The 26 is a lot more money and is not usually stocked. Just remember it will not hold screws near as good as wood. I usually mount all my hatch hinges once near finish. Then remove screws. drill out holes much bigger and make a thickened putty from epoxy or even vinylester resin.

Did you say one layer of glas just on top for decks You do not need to sandwitch to board in glass???