Yep, that's a fiberglass explorer. I have a 1985 FG Explorer I bought in similar condition. I suspect it is a few inches narrower than the newer Royalex Explorers.
It's way stiffer than Roylex, so it paddles much better in flat water. Overall a better boat than I expected it to be.
The only real rub with these are the sloppy flotation. If the hull is in good shape it's probably worth cleaning up the top foam, filling it up, then putting a small fiberglass cover over it to keep the water out. Mine used to gain about 10 lb in water weight if she swamped.