it StarBoard XL is a lightweight, marine-grade, cellular high-density polyethylene sheet that is up to 30% lighter than the original it 3/8”, 1/2” and 3/4”. Custom sheet sizes and gauges available upon . Yes, at a rate of 6×10-5 in./in./°F degrees, changing approximately 1/32 inch for every foot of length or width over a 40 .