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.