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jconover
04-18-2011, 01:20 AM
Going to post this as a series of pictures and number them. Asking the TT community for any advice on technique or approach on these specific types of gelcoat damage. I've read a lot of threads, but few with detailed pictures, so i'm including those as well so that future readers can benefit as well.

Question 1: Scratching in Gelcoat
After wetsanding and limited compounding, I'm getting a nice shine, but a lot of scratching in the black gelcoat. Before I make things any worse, could someone take a look and advise on what i'm doing wrong? Will these scratches clean up with just compounding/buffing/polishing (using a circular single axis buffer)? Or do I need to do better with my wetsanding? I'm paranoid about sanding through the gelcoat, as I have no idea what condition it is in, but a few chips in other places show me that it isn't more than 1/16" thick on the transom.

jconover
04-18-2011, 01:21 AM
Question 2:

Black is not a fun color. Here is a small scratch in my transom gelcoat. I don't think sanding is going to help me with this one. Is that a safe assumption, and if so, what is the best method to fix this type of small damage?

jconover
04-18-2011, 01:23 AM
Question 3:

Here is another small scratch (about 4 inches long), clearly through the gelcoat. This one i'm assuming I can fill with a gelcoat patch kit - should I scrape it with a 'V' shaped tool to give the gelcoat a better surface to adhere to? I hate to make the damage bigger before I repair it, and I'm a bit paranoid about getting a good color match.

jconover
04-18-2011, 01:24 AM
Question 4: This picture shows some sort of impact damage on the hull. It HAD to be right on the line between the two gelcoat colors. I'd be interested in some more detailed advice on how to repair this particular wound.

jconover
04-18-2011, 01:29 AM
Question 5: This hull has had several other repairs in the past, including a few by myself. The corner transom repair was done by the prior owner, and I am not sure what sort of material he used to do the repair, but it is very hard and sands well. He had painted it with some cheap paint that didnt match the boat well.

The small white spot in the second picture is a repair that I did last fall; it showed through to the glass slightly, but no glass damage. I dried it out and had a local fiberglass guy repair it, along with some damage to the nose. He painted the finished product with a 1-stage paint, and you couldn't see the repair, but when wetsanding this spring, the paint was sanded away. I'd like to gelcoat this, but I'm not sure where to start - it would seem that i'd need to remove some material in order to leave room for the gelcoat. Is that right? What would you do? Use a dremel/router perhaps to grind away a thin layer of the material and leave room for a gelcoat repair?

I am assuming the technique for both of these will be similar.

jconover
04-18-2011, 01:33 AM
Question 6: Last one!

Previous owner had vinyl redone. Apparently he couldnt be bothered to line up the holes from previous times, and just drilled new ones. While hidden behind the vinyl, these are still slightly visible when you stand on the boat and look down between the gunnell and the gunnell body plate. Can't stand it. Pardon the stray ladybug in the picture, darn hitchhikers. The wasp nest i found was worse.

Obviously this will require some glass repair. I am thinking of just glassing over the back of this mess, and then filling the holes with gelcoat repair, thinking potentially that some of the glass resin will seep into the holes and fill as well. I may even consider putting some clear plastic over this whole thing and using that to hold back the resin, in hopes that it will fill the holes completely and give me a flush surface to do gelcoat work on. Any idears here?

Skipper
04-18-2011, 10:11 AM
Going to post this as a series of pictures and number them. Asking the TT community for any advice on technique or approach on these specific types of gelcoat damage. I've read a lot of threads, but few with detailed pictures, so i'm including those as well so that future readers can benefit as well.

Question 1: Scratching in Gelcoat
After wetsanding and limited compounding, I'm getting a nice shine, but a lot of scratching in the black gelcoat. Before I make things any worse, could someone take a look and advise on what i'm doing wrong? Will these scratches clean up with just compounding/buffing/polishing (using a circular single axis buffer)? Or do I need to do better with my wetsanding? I'm paranoid about sanding through the gelcoat, as I have no idea what condition it is in, but a few chips in other places show me that it isn't more than 1/16" thick on the transom.

Scratches need to be removed incremently. Meaning that you have so sand (or buff) the larger scratches out first with a more aggressive paper (or compound). Then get less aggressive on the next pass. If you have already gone through the wet sanding process and you have large scratches, then you missed several stages of sanding where the larger scratches exist. Does that help?

Skipper
04-18-2011, 10:12 AM
Question 2:

Black is not a fun color. Here is a small scratch in my transom gelcoat. I don't think sanding is going to help me with this one. Is that a safe assumption, and if so, what is the best method to fix this type of small damage?

The black gelcote is gone. Sanding will only remove the remaining gelcote. One technique is to bevel out that gouge and apply new gelcote. As you said, black is difficult.

Skipper
04-18-2011, 10:14 AM
Question 3:

Here is another small scratch (about 4 inches long), clearly through the gelcoat. This one i'm assuming I can fill with a gelcoat patch kit - should I scrape it with a 'V' shaped tool to give the gelcoat a better surface to adhere to? I hate to make the damage bigger before I repair it, and I'm a bit paranoid about getting a good color match.

Anytime the damage goes completely through the gelcote the decision is already made. One method is to bevel that damaged area out. Repair any damage to the glass with epoxy resin and fiberglass mat. Then regelcote the damaged spot.

Skipper
04-18-2011, 10:16 AM
Question 4: This picture shows some sort of impact damage on the hull. It HAD to be right on the line between the two gelcoat colors. I'd be interested in some more detailed advice on how to repair this particular wound.

Same story just a little more work. You likely have fiberglass damage. Grind away all of the gelcote around the damaged area. Grind down to the fiberglass. Repair the fiberglass first and build up the area to the depth of the gelcote. Then, tape off between the colors. Regelcote the first color, then the other.

Skipper
04-18-2011, 10:18 AM
Question 5: This hull has had several other repairs in the past, including a few by myself. The corner transom repair was done by the prior owner, and I am not sure what sort of material he used to do the repair, but it is very hard and sands well. He had painted it with some cheap paint that didnt match the boat well.

The small white spot in the second picture is a repair that I did last fall; it showed through to the glass slightly, but no glass damage. I dried it out and had a local fiberglass guy repair it, along with some damage to the nose. He painted the finished product with a 1-stage paint, and you couldn't see the repair, but when wetsanding this spring, the paint was sanded away. I'd like to gelcoat this, but I'm not sure where to start - it would seem that i'd need to remove some material in order to leave room for the gelcoat. Is that right? What would you do? Use a dremel/router perhaps to grind away a thin layer of the material and leave room for a gelcoat repair?

I am assuming the technique for both of these will be similar.

Same as before, grind, bevel, repair the glass, then regelcote.

Skipper
04-18-2011, 10:24 AM
Question 6: Last one!

Previous owner had vinyl redone. Apparently he couldnt be bothered to line up the holes from previous times, and just drilled new ones. While hidden behind the vinyl, these are still slightly visible when you stand on the boat and look down between the gunnell and the gunnell body plate. Can't stand it. Pardon the stray ladybug in the picture, darn hitchhikers. The wasp nest i found was worse.

Obviously this will require some glass repair. I am thinking of just glassing over the back of this mess, and then filling the holes with gelcoat repair, thinking potentially that some of the glass resin will seep into the holes and fill as well. I may even consider putting some clear plastic over this whole thing and using that to hold back the resin, in hopes that it will fill the holes completely and give me a flush surface to do gelcoat work on. Any idears here?

Number of options. One idea is to use tape to make a temporary backing. Then fill the holes with a mix of epoxy resin and chopped fiberglass (like West 404 of 403). Use some aerosil cabosil or other thickening agent to keep it from running out. You can make it as thick as peanut butter. Or you can apply a layer of glass with some epoxy resin to the back side of the area. Then fill with filler and epoxy. Once the glass is repaired, bevel out the repair area to the thickness of the gelcote and regelcote.

check out this site (http://www.freewebs.com/billsboatworks)

Thrall
04-18-2011, 05:39 PM
I'm not sure how to handle the one that's in both colors. I guess you'd have to spray that repir and mask off the opposite color to get a good line. I've done a couple repairs but never sprayed gel coat, guess it wouldn't be too bad.
Don't worry about the color match if you Order your materials from Spectrum. They mixed up the factory color for my old boat '96 and it matched perfectly.
As others said, you'dd have to bevel out a shallow area to provide for some gel thickness. If it's too deep, buld it up with a little bondo and then grind it back out about 1/16" deep. Better deeper than not. I completed a repair and was just doing the final sanding when I burned through a thin spot in the repair.
The gel bonds better to a vertical "egde" or close to vert than "feathering it out" It will melt together where you can't see the bevel line.
The black scratchy pic, start over sanding. Either you started with too coarse of grit or got some contamination on the sandpaper that was inducing scratches as you were sanding. Start with 1000grit, go to 1200 then buff and polish.
Here's a pic, unfortunately it's not too close up, of a repair I did. Had a big nasty long scratch down into the 'glass about 2' long under the reg #'s (partly above the body line, part below, but all in the white gel. I called it a 3' job. I could see it from about 3' away, but the guy that bought it from me asked me where the repair was and I told him I'd show him AFTER he handed over the $. He had to wait, couldn't find it on his own, and he and an inboard mechanic went over the boat thoroughly before he bought it.
Good luck.

jconover
04-18-2011, 07:10 PM
Deleted - doublepost

jconover
04-18-2011, 07:11 PM
Scratches need to be removed incremently. Meaning that you have so sand (or buff) the larger scratches out first with a more aggressive paper (or compound). Then get less aggressive on the next pass. If you have already gone through the wet sanding process and you have large scratches, then you missed several stages of sanding where the larger scratches exist. Does that help?

I sanded from 400 to 600 to 800 to 1000 to 1500 and then buffed with a wool pad and Meguire's #46.

As someone else mentioned, I may have had some contaminants from one pass to the next. I can start over, assuming i dont end up sanding through the gelcote!

Luv2Ski
04-19-2011, 01:43 PM
400 grit is great for the spots with a lot of damage, but it does leave some pretty good scratches to contend with. I found that in spots where I dropped to 400, I had to spend a lot of time with the 600 and 800 to get the scratches out. Use a rubber spatula to wipe off the water while you are sanding. This provides a clear view of the scratches as you go. If you watch closely you will start to be able to differentiate 400 grit scratches from 800 grit scratches. If you buff a mild shine into it and then return to a fine grit, the deep scratches will remain shiny and really show up well when you use the spatula.

In my (biased) opinion, folks tend to spend too much time sanding. I hate sanding so I move quickly to a good cutting compound. I felt the time trade-off associated with sanding over 800 was not worthwhile . A good cutting compound will remove a consistent 800 grit scratch pattern and leave a very nice gloss. Sure, sanding higher grit may be slightly better, but these are boats not show cars and the difference was hardly noticeable and after less than one season is not visible. You could go to 1000, but 1500 is crazy talk these days - Modern compounds use an abrasive that cuts quickly at first and then breaks-down into a very fine grit which begins the polishing stage. I was amazed at the quality of the shine after just using the Meguire's #49.

I would say, in general, I probably applied the #49 twice over most of the black, 3 times in some areas that required more effort. The gray usually looked good after just one pass, except for the areas below the water line which probably required about 3-4 passes.

I assume you are using a high-speed buffer and a good pad. Makes all the difference in the world. Don't mess around with a cheepo pad or backing plate.

To address your questions:

1) See above

2) Up to you on this one. You could try some local sanding, but you may not leave a lot of gel left if you do. I did this in a couple of places with a foam block and some 800 grit. The other thought is just to let it go. It looks pretty small. You will not be able to apply a gel paste over it unless you remove more gelcoat.

3) Paste will work well for this repair. As you noted, you will need to get in there and create a nice surface by removing more gel. The 'V' technique is more for fiberglass work, for gelcoat, the edges can be sharper and still be okay. It does need to be thick though, smearing a little on the surface will not work. This does not apply if you spray it on, but that has plenty of challenges and I don't know that your repairs are worth going down that road.

4) First remove the gelocat and see how the glass looks. You may have some glass repair to do there as well. For the two colors, I had the same problem and found a good technique after a little trial and error. If you use the paste, put a good chunk on there of which ever color you want to start with, be sure it is sufficiently thick - you will be sanding it down. After it has PARTIALLY cured, you can simply come back with a razor blade and cut it off right at the transition. Then apply the other color. This results in perfect line, actually slightly better than the original.

5) For a paste, you will need to remove much of the gel. Dremmel tool or similar works well. The area on the transom is large enough you may want to consider learning how to spray gel. Unfortunately I don't have a lot of knowledge on spray so I am of limited use. But I think you would sand the entire area down a bit (probably about half of the gelcoat) and then build it back up with spray. Sand, then polish.

6) Wow, that was pretty lazy of the PO. The tricky part here is going to be getting the filler to stay in place on the vertical surface. Even the paste will run some on a large repair like these holes, you will probably need to pu8t on several coats, but I think it would work. You could also go with a bondo or similar. I don't think the holes really hurt anything other than esthetics which and will not be visible once the combing pad is back in place.

Good luck man! Very cool project, wish you the best and looking forward to seeing how she turns out!