The ALLIGATOR All-Purpose Anchor is great for attaching cleats to the fiberglass on boats. I recommend the AF6 anchor, which requires only a 1/4" dia. hole. The AF6 anchor can be used with a #8 - #10 screw and is weather and corrosion proof when installed with a stainless steel screw. Some people like to use blind-installed threaded rivets (like RIVNUT®) and other products, but they are expensive and difficult to install. The ALLIGATOR Anchor is SO easy to install, and it's a fraction of the price.
RIVNUT is a trademark of Bollhoff Rivnut Inc.