When I build my two inside storage/flotation compartments, my hatches need to be water tight. I see in my Hamilton Marine Cat. the line of BOMAR high inpact polycarbonate UV stablized deck plates that are cheap and come in sizes up to 10" in dia. The smaller hatch covers are screw in and press in while the larger ones are locking. Has anyone had any experiences with these, especially the locking type and are they water tight. I may have to call the company. Thanks.

John