I love to get on the stump regarding hull restoration! I have a NACRA5.0 that was a $700 Ebay special. When I picked it up I thought I had gotten screwed! The hulls were like chalk, the black pollution residue was all over the top of the hulls and the striping and decals were beat to heck! I told my daughters that I was going to strip it down and redo the decals and striping in a more modern motif. They were aghast at the idea. Like me, they are completely turned off by the smoke mylar look of the current generation catamarans and still long for the colorful heyday of the mid-80's. They wanted me to keep the original look. Problem is...where do you find a match to the original? My solution was to wet sand and taper what was left of the stripng and decals.
Went to the local box store and found three shades of blue that closely matched the original in rattle cans. Tape over the decals and cut out the outline with an exacto knife. Then spray the color on . For the striping use the original lines and tape them off and spray. Don't worry about runs sags etc. all you're concerned about is getting the color on. Once the paint is dry, put a few drops of dish soap in a gallon bucket and wet sand with 1000 grit automotive paper. When that is done, go over it all again with 2000 grit paper. Make sure evey square inch is covered! Rinse. When dry use Meguires Ultimate Compound over every square inch. Do this by hand not by machine! Buffers tend to "burnish" the compound and it's a bitch to rub off! Follow this with a hand rubbed coat of Mother's Carnuba wax.
I've seen all sorts of "miracle" solutions and cures for bringing hulls back to life, but the best solution is plain old elbow grease. Remember, on these old fiberglass cats, the gelcoat is pretty thick so don't be afraid to wet sand the heck out of it!
Here's how my hulls turned out. They look better than original and shine like wet glass!