What is the best composite to use?

[flyingfrizzle]

I would like to know what you recommend to use to build a composite stringer and bulk head grid. I have always used wood and thought this time about trying composites due to the rot free advantage but mainly for their lighter weight. I like the foam type blocking and sheeting but not sure how strong it would be if used for this type of rebuild. Looked at some samples at my buddies boat repair yard and the sample with a layer of 5 oz mat on both sides seamed really strong. What do yal guys recommend to use for good strength and light weight when building a grid.

[bbh57]

This is how im doing a small boat I have. First I made strips of glass. Then I stood the foam on them and tabbed them to the foam, I suspended them in place glassed the sides and tabbed them to the hull. The foam is simply a mold, the strength comes from the glassed sides. Seems to be strong enough for this small boat.

[flyingfrizzle]

I thought of something similar with foam, I was going to take a marine grade foam (like Divinycell) and make box stringers or just stand up a 1" piece vertically and fit them to the bottom of the boat. Wrap them with several layers of glass and then tab them in very well. Most of the strength would come from the glass but thought it might end up heavy in the end due to needing more glass than if it had a wood core with less thinner layers of glass. Also I thought of using Coosa, this would be the strongest and would not need as much glass over it just tabbed well. I know that the wood is strong for the small amount of weight that it adds but then I'm back to the rotting issue. I want this boat to last 25+ years. Also I would like to keep it light as possible but don't want to loose any strength.

[3rdday]

you will be fine with divinicell laminated with epoxy & biax I made the stringers bulkheads and ribs with this material. My stringers were 2" thick, I used the leftover transom core for the main bulkheads between the fuel tanks, I filled all the cavities with USCG foam.

[flyingfrizzle]

I have been using a material similar to the divincell foam. It is about the same but it has pre drilled holes threw it in rows two inches apart and the holes on one inch spacing. It is easy to work with and bonds well, once the resin makes it threw the holes it locks it in place and makes the core super strong. Also it is a bit cheaper too. No marine structural foams are cheap but it is not bad for what it is.