While it's not the boat in question, my ex-racer's cockpit is surrounded by a hopeless number of spider cracks but the cockpit trim is in good shape. (The ex-racer is my #1 Sunfish—#2, ready to sail, is in excellent condition). I'm a few weeks from viewing Sunfish #3 (with #4 & #5 standing by) which got the cockpit trim replaced. (Thanks to Alan Glos ). When I get there, you'll get a full report. Does it stiffen the deck? I think, if you removed all the pop-rivets on the aluminum cockpit trim—and sat on the "unstiffened" deck—I'll bet the trim will pop right off. Riveting (but especially gluing) permits the trim to become a structural part of the deck. It especially helps against strain at the fiberglass margins. IMHO.