I have done several things for customers, depending on both the customer and the advisability. For one customer, I installed 1/4" safety glass (cut by a glass shop) which he had tint installed on the inside after I''d sealed the panes in. It was definately a ''sunny day harbor boat'' and he insisted on being able to wash the boat like a car and feared hazing plastic. For other customers I have installed varying thicknesses of clear Lexan, and for others, various thicknesses, usually at least 1/4" but sometimes up to 1/2" (Which I have in my own portholes) tinted plexiglass. If you''re carefull washing the plastic and use approved plastic polishes on it, it seems to last prety good.