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Catalina "smooth" gel coat has a pebble grain texture. Is this normal?

3K views 13 replies 7 participants last post by  SHNOOL 
#1 ·
Greetings all -- I'm working on a 1986 Catalina 24, trying to buff out the topside fiberglass, which is quite oxidized. What's weird is that the gel coat, even in the nominally "smooth" areas has a definite texture to it. It's sort of like really bad orange peel on a car. Because of this, it's really hard to buff the gel coat to any real shine.

This boat seems partly neglected, and partly suffering from overly aggressive cleaning along the way. (Current owner mentioned the use of Soft Scrub and also bleach.) Leaves me wondering if I'm seeing where the gel coat has been damaged.

Has anyone else encountered this or something similar? I don't want to risk wet sanding the existing gel coat to smooth it up, because who knows how much gel coat thickness is still there on an older boat.

Would appreciate any suggestions or thought.

Mark
 
#4 ·
Look for a chip in the gelcoat, that might help tell how thick it is. Some flat surfaces on my Boat show some print through from the cloth but only with the sun just right. I would get the topsides as shiny as possible and the deck benefits from a little non slip from a less than perfect shine.
 
#5 ·
Hmm. The owner didn't say the boat had been painted, but I didn't ask. As far as length, he described the boat as a 24, and she looks about that length. Will double check.

Another interesting wrinkle on this boat is one of the owners washed the topsides with bleach, and now the foredeck is quite yellowed. I'm going to try my usual boat soap and see what happens. Any thoughts on what bleach might have done to older gelcoat?

Thanks, Mark
 
#6 ·
I'd find it surprising, if a single wash with bleach did anything noticeably destructive. Many use it to recover from a mold infestation. However, common advice is to not use bleach repeatedly. It's a harsh chemical, which will ultimately dull the gelcoat and I wouldn't be surprised if it could alter the pigment in the gelcoat over time. If it did the later, it's permanent, I'm afraid.

If you determine is was not painted, maybe it's some sort of tanic staining, which is more likely if around the waterline. Oxalic acid or On-Off should take that off fairly easily. Wax it up well afterward, if this works, as the old gel coat needs to be sealed to deter it from recurring.

If still a problem, you may want to resort to a wet sanding, compounding, buffing regimen to see if you can restore the flat portions of gel coat. I know of no way to effectively restore permanently damaged non-skid, other than grinding it down and re-applying a replacement. It would have to be very, very, very bad for me to even consider doing that.
 
#7 ·
I'd find it surprising, if a single wash with bleach did anything noticeably destructive. Many use it to recover from a mold infestation. However, common advice is to not use bleach repeatedly. It's a harsh chemical, which will ultimately dull the gelcoat and I wouldn't be surprised if it could alter the pigment in the gelcoat over time. If it did the later, it's permanent, I'm afraid.

If you determine is was not painted, maybe it's some sort of tanic staining, which is more likely if around the waterline. Oxalic acid or On-Off should take that off fairly easily. Wax it up well afterward, if this works, as the old gel coat needs to be sealed to deter it from recurring.

If still a problem, you may want to resort to a wet sanding, compounding, buffing regimen to see if you can restore the flat portions of gel coat. I know of no way to effectively restore permanently damaged non-skid, other than grinding it down and re-applying a replacement. It would have to be very, very, very bad for me to even consider doing that.
Bleach is bad for your stainless as well. Cleans that invisible protection that salt water wash will not.
 
#8 · (Edited)
if it is not smooth then it has been coated with a paint or gelcoat or some material has be eroded away. it was smooth when it came out of the mold. sounds like it may be painted. gelcoat when sprayed always comes out orange peel finish and needs to be wet sanded to be smooth. when eroded it has a surface like concretes the solids are worn away. is the whole boat this way or just in areas? if you have not already, read this thread by Mainsail it is the right way to do stand the best polish compounds to use.
https://www.sailnet.com/forums/gear-maintenance/52772-tips-compound-polish-wax.html
 
#11 ·
I know I'm coming in late on this, but is it possible that you're seeing osmotic blistering? I have a small sailing dinghy that was stored under a cover for a year, and unfortunately moisture found its way between the cover and the deck. I ended up with small osmotic blisters over part of the deck, which looks sort of like pebble grain. I have left it as-is, because the only solution is to pop them open by hard sanding, dry them out, and redo the gelcoat. That is far more than the boat is worth. What you described sounds similar. Perhaps leaves fell onto your deck and trapped moisture against the gelcoat.
 
#12 ·
Some notes.
Soft Scrub with bleach is actually, um, soft. It does have mild abrasive, but it wouldn't put a dent in gelcoat.

To damage gelcoat as you you describe would require something of a larger sort, as I've used 80 grit sandpaper to no avail at damaging gelcoat (attempting to smooth).

2 common catalina boats and sorry for my prior sarcasm I was having a bad day... of that vintage (which is honestly quite new if it really is a 1986)... and size...

Catalina 25:

Catalina 22:


Catalina had pretty decent gelcoat process down in their boats by the 1970s, and 1980s they were pros. If you are truly looking at gelcoat (I think you are looking at awlgrip or similar 2 part that has aged), then you can use a wetsand, compound, polish wax method to shine it up... or you can take the REAL lazy approach like I have a couple of times and just polyglow it and go sailing. There will be purists here who say NO NOT POLY GLOW, and I am here to tell you, life is to short to waste sailing time on compound polish wax and repeat, cause every 6 months you'll need to rewax.
 
#13 ·
Some notes.
Soft Scrub with bleach is actually, um, soft. It does have mild abrasive, but it wouldn't put a dent in gelcoat.
Bleach is highly alkaline and will damage gelcoat. As I said, probably not so much, if used once. Probably less noticeable, if the gel cost is already damaged. The issue is not that it's mechanically abrasive.

.......I've used 80 grit sandpaper to no avail at damaging gelcoat (attempting to smooth).
How's your eyesight? :)

There is no way that course sandpaper would not leave actual scratch marks. Even wet sanding with superfine paper needs swirl marks buffed out. Maybe the gelcoat you sanded was just that bad to begin with and it simply didn't get worse.
 
#14 ·
Minni I get your point yes it DOES scratch the gelcoat, but not easily. Gelcoat is not like paint. If there is any thickness to it (the gelcoat) then you can do an awful lot of rubbing to it before it creates a cracking. Impacts maybe, that'd do it. Softscrub with bleach will dry the surface and open the gelcoat to oxidation (more oxidation) which is the reason why you must reseal it to prevent that.

The 80 grit I used, was to level applied gelcoat, then was followed by successively higher grain until eventually compound, polish, and wax to bring it up to a shine. What I call a 10 foot shine, cause after all it was a $7500 boat, that was 40 years old, that had more repairs than the average 70s Ford Pinto.
 
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