Sandpaper advice

[tunawish]

I have no experience restoring previously painted boats. My past 3 projects were all done in Gel Coat. The PO had the B20 sprayed with either Awlgrip or Imron 7-8 years ago. The prep looks lousy and the paint quality is just OK but at least it's not peeling. Except for the engine box, which has badly crazed and pock marked gel coat under it and is flaking off all over the place. I thought a temporary solution till I can do the whole boat would be Interlux Perfection roll and tip over an epoxy prime coat after sanding off all the crazed gel coat.
I've seen some incredible results using this stuff from some guys who have trouble waxing.

Spent the past 3 hours trying to get the paint and gel coat down.
I'm using 3M Green Procut 40 grit paper on a pretty aggressive 5" Dynabrade sander and I'm maybe 1/2 done.
What the hell is this stuff made of? Is this paint that hard or am I using the wrong paper. It's not loading up but seems to loose it's cutting quality after about 2 minutes.
What are you guys using for paper? Does the gel coat have to come all off
or will the epoxy prime coat fill the crazing and pock marks as it says it supposed to.

Thanks
Ray

[Skipper Dick]

Ray,

When I had to remove blisters and gel coat on a Bayliner a few years back, I used 30 grit on a 6" orbital sander. It took me about 4 or 5 days to get the bottom gelcoat off and I went through 3 suits and 4 paint masks doing so. It is hard stuff. Then it took me another 3 days to fair it all out with an epoxy fairing mix. I used 80 grit to fair it and then put a couple of coats of a barier coat on before putting bottom paint on. It turned out great even for a bayliner. It is hard and it is hard work.

Dick

[jspiezio]

Have you guys ever heard of Osmotech in Annapolis? The owner, Marty Munch, has a very specialized grinder for removing paint and gel coat where they are blistered.

I don't know if he sells them, or if someone sells them for him, but it might be worth calling if it saves a lot of time.

(410) 280-9704

Just want to say I've never used them so I can't speak from experience, just passing along what I've heard.

[tunawish]

J

Not sure if it's the same one but I've seen a peeller for gel coat used before it was on a sail boat.
It seemed to work great where they could take one long vertical cut from water line to bottom of keel.

I don't know how good it would work on our boats with all the strakes.

I have the Norten rep coming by the shop this week. I'll see what he recommends for paper...

Ray

[jspiezio]

J

Not sure if it's the same one but I've seen a peeller for gel coat used before it was on a sail boat.
It seemed to work great where they could take one long vertical cut from water line to bottom of keel.

I don't know how good it would work on our boats with all the strakes.

I have the Norten rep coming by the shop this week. I'll see what he recommends for paper...

Ray

THat makes sense, this guy does a lot of sailboats. Swan in particular.

[scot]

The entire hull on my 25 is crazed, badly. "someone" did and excellent job of priming and painting about 10 years ago and the hulls sides still look great. This is VERY hard paint and difficult to feather, I think it must be Dupont imron.

The cap is another story. I decided to strip the cap of all gelcoat, fair and paint.

I used a 10,000 rpm 4" mini-grinder with a sanding disc, we call them tiger disc? They are multiple layers of sand paper bonded onto a wheel. Eats it right off. In fact if you left it in one spot it would eat right through the hull....so you have to keep moving and pay attention not to dig in. But fairing and 5" Randum orbital sander is required to get everything flat and pretty for paint.

I'm glad I did it. The boat will look good. Now I'm debating the bottom. I think sandblasting is the answer for bottoms, it you want to keep your back functional.

[tunawish]

Scot
The Norton guy was in today and that's what he recommended, a grinding disc.
I was trying to stay away from it to keep the surface as flat as possible and reduce the sanding/fairing.

So he is sending me some 40 grit Zircon ?? or Zircite?? impregnated disc for the 5" DA. The cutting quality is
supposed to be 5 times better than what I was using...

We'll see

Ray

[scot]

Ray,

Let me know how that works, I still have a nasty bottom to contemplate and if I can find a DA disc that is aggressive enough to take off the gelcoat it will diffinately be less work overall than the 4" mini grinder + sanding wheel.

This is the style I'm currently using:

The flat area is better than the square egde of a hard disc. Much easier to keep the grinder from digging in, also very smooth and easy to control. But still WAY TOO MUCH WORK!
Thanks