Have all the above boats
And never 303 'ed any of them. Nor wax
They are fine after 23-3 years. Not much sun exposure on overturned hull
I learned long ago about the virtues of having a slip free interior and no more 303 in there
303 does help in washing pond scum off without scrubbing. In Maine that is not a issue but in algae choked waters it could be
Millbrook recommends yacht wax.
Millbrooks have no gelcoat, only a thin layer of pigmented vinylester resin before the cloth goes in the mold.
303 makes a nice ritual, but the basis for using it is not objectively established. The same can be said for waxing.
Run fingers over the surface
Same for waxed vs nonwaxed vehicle sheet metal. The nontreated surface is less slippery.
3-5 weeks
Usage Directions:
Use only on clean surfaces. For best results use 303® Multi-Surface Cleaner™. Place a drop cloth under the cleaner to be treated to catch any overspray. Out of direct sun, spray surface with 303® Aerospace Protectant™ and WIPE COMPLETELY DRY. If streaking occurs, too much product has been used. Use a wet towel to remove excess, IMMEDIATELY WIPE COMPLETELY DRY. Note: this product does not air dry. Extra buffing with a dry cloth INCREASES bonding, repellency & longevity. Apply every 3-5 weeks for maximum UV protection. Great for use on a variety of surfaces such as: vinyl, leather, plastics, synthetic & natural rubber, eisenglass, PVC, teak, gel coat & fiberglass. Ideal for: Hypalon inflatable boats, wet/dry suits, tires, side-out seals, RV EDPM rubber roofing (for your safety, never walk on a wet roof), helmets, visors, and goggles. Not for use on unfinished leathers (such as suede), fabrics (canvas) or floorings.
45 per gallon
I have a Boston Whaler the wax 3M marine on the hull exterior beads water for over a year, The deck and flat horizontal surfaces a month or two. Use 303 on it now in areas with flat surfaces during the season. Fast and easy. I see it on fleabay shipped for 45 a gallon.
Buff
Buffing 303 by hand with dry cloth does bring a better shine. Just tried some NU-Finish along side 303 and 303 gave it a better shine.
Not objective data, just advice
calculated to get buyer to use 303 as often as reasonably possible. “For maximum UV protection…”
When water no longer beads
on the treated surface. I recall reading this on the 303 website.
I use it on my hull and neoprene gear.
When I had my pontoon boat, I faithfully applied it about every two weeks to the vinyl seats since the boat was never covered; just left the bimini up. Those seats looked as good as new this spring, when I sold the boat.