Need HELP with gelcoat.

Old 05-02-2002, 09:32 AM
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It all depends on the depth of the scratchs you are refering to. First, determine the type of scratch, is it a swirl scratch or a deeper scratch. The swirl scratchs you can not feel. When you look at them with the correct light they do not have any depth to them. If they truely are swirl scratches do the following:
Clean boat very good.
Polish with buffer running at 1600-1800 rpm.
Polish to use is 3M FineseIt-II, use this with the yellow foam pad from Mequires. This will not cut but polish only.
When complete you will not see any swirl scratchs.

If the scratch is more than a swirl you will need to use the compound and a wool bonnet on your buffer. Run about the same speed. Use the compounds listed by others or try Meguires #49. Follow up with #45, then 3M FineseIt-II.

It the compound does not take out the scratches then you will need to wet sand. Start with 800 then 1200 and or 1500. Then repeat the compound process above.

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Old 05-02-2002, 09:59 AM
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ONLY use the 600 if the original scratches are to deep to remove with the 1000. You said that it looks like someone went over the hull with a Scotch Brite pad. These pads are a hell of alot more abrasive than 1000 and even 600 for that matter. For example, you cannot remove 80 grit scratches with 320 grit. Not abrasive enough. You would have to go to 120. Then 240 to remove the 120, 320 to remove the 240 and so on. You get the idea. So, depending on how deep the original scratch are depends on what grit you will start with. As stated before, start with the compund first and see how that turns out. Then adjust from that point.

600 does seem kind of course, but the sides of my hull were in rough shape. They actually felt like sand paper when running your hand over them. Now they are like a mirror and smooth. Every piece of literature I read on gel coat repair had a finsh grit prior to buffing of 600. That is how I made my determination on what grit to use.

I WOULD NOT wet sand the corners as Meguires eluded to. Too risky.

The buffer you are going to rent sounds like the wrong type if it is an orbital. It needs to be a rotary. The orbital has a sort of dual motion (like a sanding DA) of spinning and vibrating.It does not build enough rpm to be effective with the rubbing compound. The rotary buffer only spins which will have enough rpm.

I am not an expert, but have experience in this. Some good and some bad, but that is how I learn.

If you want give me a call at the office or on my cell.

office 847/368-5594
cell 773/837-1008 After 10a.m.C.S.T

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Old 05-03-2002, 12:59 AM
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Thanks for all the help. I was in Denver all day and just got back to NYC so I just got on now to respond.

I'm going to check over my friend's boat with him before we begin. From what I remember, the deck has scratches that are very fine and which you cannot feel but you can see. He said that he did not notice them until late last season and he did not have a chance to work on the boat before he laid it up for the season. He thinks that they appeared after the boat was detailed and he thinks they look like the cleaning agent was too coarse.

Now, on one or two spots on the hullsides, just below the rubrail, and covering almost the entire area of the waterline, are deeper scratches. These scratches you can feel and see more readily. They were clearly caused by someone using too much abrasion in removing any scum. I know that a guy we have both used locally for cleaning does use the Scotch Brite pads to clean the hull bottom if you want. I kow some people think that using sandpaper or a Scotch Brite pad is a good thing, but someone screwed up it looks like and went up on the hullsides a few inches. Now, my friend is a perfectionist, so he wants everything to be perfect. We'll see what happens.

I think the game plan is to buy or rent (depending on what the selection is for sale) a good, high-speed sander/buffer/polisher and spend some quality time with the boat. I think we'll wash the boat thoroughly and use the heavy oxidation remover as well. Then we'll get to work. The idea is to use some 3MF2 on the deck in a small spot and some more on the hullsides where it is scratched and a third time in a small spot at the water line. From there, we'll determine if the deck needs a stronger compound and what the hullsides and the water line will require. If need be, we'll use the wet-sanding technique for the worst scratches.

No matter what, the entire boat will eventually be gone over with 3MF2, 3MPerfect-It, and some kind of really good wax, so hopefully the whole surface will be even and mirror-like.
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Old 05-05-2002, 09:25 PM
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Well, thanks for all the help. We did need to wet-sand, but the results were worth it. We didn't finish everything yet, but we did get most of his boat done and the final result was excellent.
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