Maintaining Fibreglass - 2004 Cat

[trest1]

I would really appreciate any advice re maintaining gelcoat/fibreglass on my newly acquired cat. Currently she has some oxidisation light to medium and being over 40 feet will need lots of work. Would really appreciate advice re products for sunny Queensland Australia

[AbaftAndBaffled]

Originally Posted by trest1

I would really appreciate any advice re maintaining gelcoat/fibreglass on my newly acquired cat. Currently she has some oxidisation light to medium and being over 40 feet will need lots of work. Would really appreciate advice re products for sunny Queensland Australia

Depending on thickness of gelcoat, just sanding will fix that. 180, 280, 400, 600, buff to shine. If gelcoat is too thin, spray some fresh gelcoat!

[colemj]

Originally Posted by AbaftAndBaffled

Depending on thickness of gelcoat, just sanding will fix that. 180, 280, 400, 600, buff to shine. If gelcoat is too thin, spray some fresh gelcoat!

Yowza! Don't follow this advice!

If it is in really bad shape, then wet sanding may be in store, but NOT the grades listed above. You should probably START with 600 at the heaviest (that would be a boat in very bad shape) and go up from there. It has to be wet sanded, not dry, and it needs to be done correctly.

If you start at 180, you can kiss the gelcoat goodbye and start pricing paint jobs. It will not buff out after 600 either. You will need to be well above that before buffing. Maybe cutting compounds could take it from there, but easier to wet sand.

But try a quality rubbing compound made for this type of work first, and use good equipment. If it is in bad shape, simply using turtle wax products and a cloth is not going to make a difference.

A new gelcoat job is going to cost big bucks. I would estimate $20-30k for your boat. After all, the old gelcoat is going to need to be sanded back into fresh state before new can be put on, so you will be going through part of the procedure anyway.

Mark

[FLLCatsailor]

I would start with an angle grinder, and then go from there...

[AbaftAndBaffled]

Roughing gelcoat at 180 is pretty standard for us, though in his case I'd only do that if, like I said, the gelcoat was thick enough (and if there are pits in the gelcoat - at that point you're going to have to get in there anyways). We don't wetsand so I can't speak to that, but doing a 40 ft boat starting at 600 grit sounds like a full-time job in and of itself.

[barnakiel]

I never sand gelco if I am going for the aesthetics. Soap/Wash/Wash it down very, very well, let it dry then apply plain car wax (without rubbing compounds) and buff. Then apply more wax and buff again. Then look.

If at this stage your gelco looks dull, only now it is the time to consider a more radical method.

I have never found any superior wax but I found that some apply better than others. I prefer gel/thick over liquid. Avoid working in sun/heat too - the wax will dry instantly rather than soak into the gelco. Early mornig / late evening best time IMHO.

I wax/buff by hand, but if you have big/flat areas on a bigger boat, go with a power tool.

b.

[Cotemar]

Start with Collinite No. 920 Fiberglass Boat Cleaner

[colemj]

Originally Posted by AbaftAndBaffled

Roughing gelcoat at 180 is pretty standard for us, though in his case I'd only do that if, like I said, the gelcoat was thick enough (and if there are pits in the gelcoat - at that point you're going to have to get in there anyways). We don't wetsand so I can't speak to that, but doing a 40 ft boat starting at 600 grit sounds like a full-time job in and of itself.

I can't imagine what gelcoat dry sanded with 180 grit looks like. Even dry sanding with 600 must leave it a mess of scratches. Wet sanding with 1000 can make pretty fast work out of moderately oxidized gelcoat. I don't think dry sanding would work at all.

Mark

[atoll]

i have found phospheric acid good for removing oxcidization,acetone for general cleaning,then buffing with wax or silicone polish.
a mixture of bleach and washing up liquid will also do wonders before hitting it with more stronger cleaners.

sanding with very fine paper would be more of a last resort,best left to experts in gelcoat repair!

[AbaftAndBaffled]

Originally Posted by colemj

I can't imagine what gelcoat dry sanded with 180 grit looks like. Even dry sanding with 600 must leave it a mess of scratches. Wet sanding with 1000 can make pretty fast work out of moderately oxidized gelcoat. I don't think dry sanding would work at all.

Mark

I'm starting to wonder if there's some sort of Imperial/Metric grit difference going on here, lol. 600, imo, leaves gelcoat looking 'natural' - shines, but not polished and gleaming.

[atoll]

Originally Posted by AbaftAndBaffled

I'm starting to wonder if there's some sort of Imperial/Metric grit difference going on here, lol. 600, imo, leaves gelcoat looking 'natural' - shines, but not polished and gleaming.

the grading of glass paper is pretty universal,and i belive refers to the amount and size of grit per 1/10th of an inch square,ie 40 grit being very rough and 2000 very fine

[nimblemotors]

This is what I did to make my ski boat shine. Gelcoat was toast, buffing did nothing.
Wet sanded it with 400, then sprayed it with 2-part urethane clear that I use painting cars. Looked great, 10 years younger, like it was only 5 years old instead of 15..

[neilpride]

Originally Posted by atoll

i have found phospheric acid good for removing oxcidization,acetone for general cleaning,then buffing with wax or silicone polish.
a mixture of bleach and washing up liquid will also do wonders before hitting it with more stronger cleaners.

sanding with very fine paper would be more of a last resort,best left to experts in gelcoat repair!

+1.. phosphoric acid clean well gelcoat, you can laugh at me, but here the charter companys use toilet bowl cleaner to scrub the decks , and it work!! there is some amazing rubbing compounds and polishes in the market to bring the shine again....

[colemj]

Originally Posted by nimblemotors

This is what I did to make my ski boat shine. Gelcoat was toast, buffing did nothing.
Wet sanded it with 400, then sprayed it with 2-part urethane clear that I use painting cars. Looked great, 10 years younger, like it was only 5 years old instead of 15..

But that is a lot different. You painted the boat, not restored the gelcoat. So 400 wet sand prep is correct. The gloss comes from the clear coat paint, not from the gelcoat.

How easy is it to repair clear coat? I thought on cars it was difficult.

Mark

[nimblemotors]

Originally Posted by colemj

But that is a lot different. You painted the boat, not restored the gelcoat. So 400 wet sand prep is correct. The gloss comes from the clear coat paint, not from the gelcoat.

How easy is it to repair clear coat? I thought on cars it was difficult.

Mark

Yes exactly, how shiny depends on how smooth the surface and how well you apply it.
(to really get a shine, do multiple coats and sand between, show cars they go crazy..)
You don't 'repair' clear coat, it can peel which is bad, you have to sand it all off in that case.

And btw, I only did the dark blue part of the hull because it wasn't dark blue anymore..the white part of the boat, it was still white.