Coosa board instead of marine plywood for stitch and glue boat?

[fallguy]

Rarely, if never, build a boat heavier on purpose. Save perhaps a ballasted boat.

So then the only question is stiffness. And more glass is the typical solution.

But Coosa is about the same weight as ply.

The typical way to get the same stiffness, for the same (or higher) weight materials is to use vacuum to reduce resin content.

 

[gonzo]

Coosa board is lighter than plywood by 30-40%.

The Coosa board is 32lbs/CF and okume plywood is about 29lbs/CF. That is not 30% lighter. Further, the okume plywood is harder and stiffer. The data is from the manufacturer. Coosa board has some advantages, but less weight is not one of them.

 

[Lannie M.]

The Coosa board is 32lbs/CF and okume plywood is about 29lbs/CF. That is not 30% lighter. Further, the okume plywood is harder and stiffer. The data is from the manufacturer. Coosa board has some advantages, but less weight is not one of them.

Appears that reference is for just one of the 3 options---bluewater 32, the least popular flavor. 26 is the most commonly used (based on sales), and 20 the third variant.

I assume this fella meant/ was referencing bluewater 26, being lets call it 19% lighter....lamination schedule variants aside right.

Either way, no way I'd use Coosa for a whole build, that seems to be financially and pragmatically insane when Divinycell H100 or one of the other flavors is less than 50 cents on the dollar the cost of coosa (yes at significantly less density) and you can easily put coosa inserts into planned screw areas.