Big Buffalo

im trying to figure out what would be the best way to attach the inspection hatch onto the GRP deck...I believe the hatch is made out of 6mm plywood, and im thinking...could I just use small hinges and then some sort of thumb screw on the other side.... so I can easily open it up, etc... and use some sort of rubberize (or whatever) rimming on the hatch door rim...to help keep water out. would the hinges & thumb screw(s) be a good idea or does somebody have a better idea?