Coosa structure and divinnycell core on mine. Was redone by me many years ago. Vinyl resin and 1708 glass. The boat hull is a very light, tight unit with no flex or cracks. You can use wood for a more quiet ride. I just like working with the foams and core board better. Running a 250 optimax (505#'s) , no concerns with the trans or hull after a lot of miles. Including ruff salt water.