It is polycarbonate, i knew it was not perspex but could not remember the name. They use it for certian illuminated signs... i think they stick vinal onto it infact.
Thanks for the complement about the RIB, i've developed a method of making the paddles turn in a circular motion by attaching a 2.5lt v6 engine to them, you can just make it out in that picture at the back of the boat but i think "tango" was towing me at the time
Somewhere in the gallery you'll find a substantial thread about the fit-out of this boat, it's called 'my new toy' i think.