Cast
Acrylic V Polycarbinate
Cast Acrilic has better scratch and chemical resistance, and far better UV resistance, Polycarbonate wins for absolute strength, but acrylic is a far better material for most boats. Polycarbonate gets its impact resistance from slight flexibility; large, unsupported polycarbonate hatches can sag where acrylic hatches will not. Unless the boat operates in an
environment where impacts are likely, you will get far better performance from an acrylic
hatch. As an added benefit, acrylic is much less expensive than polycarbonate.
Lewmar use cast acrilic the only hatch manufatture that I know that uses polycarbinate is
Bomar
Why use CAST Acrylic verses EXTRUDED Acrylic ?
Continuous
Service Temp: 180 F (Cast) vs. 160 F (Extruded)
Cast acrylic has a higher molecular weight, therefore it will cut, drill and rout cleaner. As you machine cast acrylic, the shavings will flake off whereas the extruded acrylic shavings can gum up on the tool.