help please Epoxy on EPS finishing

Happy Thanksgiving everyone.

I will be building an outrigger float using a solid core of 2 pound density EPS

foam covered with 10 ounce glass fabric and epoxy.

What can I use as a fairing product to get the float ready for primer and paint?

I was planning to use a ONE part Polyurethane as the finish coat.

 

2 pound density isn't structural. I don't consider this foam structural unless it's at least 5 pounds.

You can buy a premixed fairing compound, such as System Three's "QuickFair" or you can make you own, with epoxy and light weight fillers, such as Q-cells and micro balloons. Once satisfied with the fairing and smoothing operations (nope, they're not the same), you'll want a good epoxy primer, especially if applying a single part polyurethane over it.