Extensive Gelcoat cracking and grazing

[mvweebles]

Originally Posted by BruceS

Some time ago I had a 23ft power boat that had a lot of 'crazing' that I fixed/hid a different way than a lot are advising here.
I broke an 1/8" drill off so I had a square sharp end, put it in a drill & just laid it at a 30 degree angle to the surface and chased all the cracks down to the cloth.
After a quick wipe with acetone cloth I filled all the cracks with a fine sign writers brush with gelcoat till slightly over filled.
Wet & dry to rub down flush finishing with VERY fine one.
A good wax & polish & you couldn't see where I'd fixed it.
No painting at all.
Give the whole topsides a good cut, wax & polish .........

Essentially the same process for repair of serious cracks - gouge-out, fill, sand, fair. Only piece missing is I believe the boat will need a complete paint job when complete - I doubt the job would look complete without a full paint, but who knows. Might be the 80/20 rule in action (20% of effort yields 80% of benefit).

[Mackie]

You guys are doing it all the hard way. First, be sure all moisture is gone. Grab a heat gun to be sure then use crazy glue to fill cracks. It will penetrate the area and completely fill and seal all voids no matter how small or large. When properly cured, wet sand down to 2k grit and then buff. All but the very worst cracks will be invisible. I have been using this method for years on countless jobs & they never come back!

[GordMay]

Greetings and welcome aboard the CF, Mackie.

[Greg K]

I owned a 1979 Cape Dory 36 that had a similar issue with gelcoat cracks. As Most people are saying here, basically a cosmetic issue. In my case, most of the cracks were in non-skid areas which needed renewal anyway. Was relatively easy and inexpensive to deal with. When we got down to Venezuela, I painted all of the non-skid deck area with Imron mixed with non-skid fine sand particles and it was as good as new. 10 years later when I sold the boat in Turkey it was probably due for another coat soon. Cape dory 36 is a wonderful seaboat, so if everything else is in pretty good condition, the gelcoat cracks would not be a deal breaker for me.

[Squanderbucks]

If you just lightly or even moderately sand the deck and can still seel cracks in the gelcoat and try to coat over it whatever you put on will not fully penetrate and fill in the cracks. It will look good for a while and then come right back.

All gelcoat needs to be removed and recovered with a new barrier such as gelcoat or epoxy for the purpose.

I would consider removing the gelcoat and using a polyester product called SlickSand. It is laike a high build primer and has excellent coverage properties and is easy to sand and is much much less expensive than Awlgrip products.

I use it for projects all the time. Excellent. Then paint with whatever you want.

[sailingchiro]

depends upon if you can live with it. I couldn't and spent $16k to have all the cracks ground out and repainted with Awlgrip.

[dennismenace111]

Ive got a 1987 Watkins 29 with lots of gelcoat cracks on the deck and in the cockpit seating areas.

Im leaning toward sanding the area down, and priming with thinned out epoxy primer and then overcoating with Kiwi Grip. All of my cracks, are in the non skid areas, so Im thinking that the thicker material will hide them better..

Any thoughts?

[Greg K]

Originally Posted by dennismenace111

Ive got a 1987 Watkins 29 with lots of gelcoat cracks on the deck and in the cockpit seating areas.

Im leaning toward sanding the area down, and priming with thinned out epoxy primer and then overcoating with Kiwi Grip. All of my cracks, are in the non skid areas, so Im thinking that the thicker material will hide them better..

Any thoughts?

That's more or less what I did with my former CD36 in Venezuela years ago except that I used Imron, a local two-part, epoxy like aircraft paint. I did the job myself using good quality brushes and a fine non-skid sand mixed into the paint. My only problem initially was that in the tropical climate the Imron was going off too quickly for painting by brush, and I had to ad retardant to slow it down. The job looked like new when finished and only started to show some deterioration after about ten years or so.

My only advice would be to put the epoxy primer on thick ( don't thin it out) so there is a good, thick coat over the whole surface before overcoating with Kiwi Grip. And use good quality brushes.

[dennismenace111]

For what its worth, i was goingb to put a thinned down priner coat first to fill the cracks. Then follow up with an unthinned coat of primer to build up and hide the imperfections. I'm in South Florida so, Ill have to take the ambient temperature into consideration!

I'm familiar with imron having painted a few dozen airplanes in a previous lifetime .

I'm leaning towards Kiwi Grip to help hide the imperfections and because it's one of the few non skid paints that can be custom tinted and has no aggregates in suspension which can wear thru over time.

[Tillsbury]

There are way too many cheap old small monohulls for sale to be wasting your time with one like that...

[boatpoker]

Originally Posted by weephee

I'm looking to purchase a 1983 Cape Dory 36 which has a lot of crazing and cracking of the gelcoat all over the deck, not just in a particular location as per the pictures below. Any ideas as to what would be causing this damage and can it be repaired. Is this boat worth pursuing. Thanks

The photos do not look like gelcoat crazing to me. They look like cracks.
Have you sounded the deck ? Have you moisture metered it ?

It is possible to repair gelcoat crazing (expensive and time consuming) but patching cracks is a waste of time unless you also repair the underlying cause.

Moisture Meter Mythology and Flir thermal imager

[dennismenace111]

Its certainly worth a couple I hundred bucks on materials and a week or two of part time effort! Im retired and have lots if time!

[Greg K]

Originally Posted by dennismenace111

Its certainly worth a couple I hundred bucks on materials and a week or two of part time effort! Im retired and have lots if time!

Agree. Absolutely worth the effort and minimal cost. Good luck with the project.

[sailingchiro]

I would make sure the deck is completely sound, meaning no water intrusion or softness. Also, a dremel with a small bit to clean out the crack then refill with whatever, this is the first time I heard of using super glue, may give it a try.
I guess a guy can fill with epoxy, high build, super glue, etc. Just need to get it clean prior.

Another option that I would have considered prior to paint is to wrap the area with vinyl. It is cheap, easy to apply and will last about 6 years before it will need to be redone. Just cut along the non-skid and press on after cleaning the surface. It will take a weekend, about $50 of vinyl and some determination. It will also seal the area from weather. Just my thoughts.

[Aethelwulffe]

#1 Don't use high-build primer...ever. It absorbs moisture, and then mold grows in the stuff. You can take a sander to a lot of boats and find out this is true.


#2 Paint does not get rid of the cracks. You will see them.


#3 Fixing this for real isn't that complex.


So...You have removed all the hardware, and given everything an 80 grid DA sanding down to fresh color. FOR THE FOLLOWING PROCESS do not bother doing anything to the non-skid areas. Use those as you working areas. We take care of that later.



You then mix up some 1:1 epoxy resin (laminiating resin, high adhesive strength. You now either spray or roll and tip (avoid bubbles) and squeegie it on the whole deck or hull. Lay it on the horizontals THICK, and work it in with a spreader on those areas. Do this in either big, slow curing batches of resin, and keep a wet edge. KEEP it out of the SUN or you will get a mass of bubbles.


You may notice that where you put the material on in sufficient thickness (1/16 inch, 2mm) that the epoxy has self-leveled when curing, and has given you a slick mirror like finish over the cracked old polyester gelcoat.



You now have a "candy-coated" boat. You may see some through-print of cracks on vertical areas. Wash the layer, or wipe (one direction, not waving a rag back and forth) down with alcohol, a scotchbright pad, and a rag to get the amine residue off the surface.


Test sand those print-through areas (which may not exist at all). If they are a problem, sand and re-coat with the straight resin.


Now sand the crap smooth, and handle anything else with epoxy and cabosil filler. Avoid the other "lightweight" fillers.


You can now sand to a smooth finish (220 - 320 grit).



Go to your paint store. Tell the salesperson you don't need no dang primer. Get Awlgrip or Sterling or some other good tough linear polyurethane two part paint (not Imron).


Spray or roll and tip with properly thinned and catalyzed (right kind of catalyst for the application method) in a thin-to-win painting scheme. Use small radius foam rollers, and *ultra-high density* 4 and 6" foam brushes. The brush tips or applies the paint while moving very very slowly and in one direction.


All painted now. Evaluate for a second or third coat if you can see through that very thin coat you applied directly on top of the epoxy resin. Prep with scotchbright pads on orbital sander to remove the gloss between coats.


By time you are done with the second coat, you will have learned how to run the foam brush slow and patient. Woohoo. You are now a real painter, and the stuff is at least as good a sprayup.


NONSKID.


Pull all your tape, fix any under-tape boo-boos where paint strayed onto your hatches or toe-rails etc...


Tape and paper off most of your fresh new paint, unless you are confident you won't goof up the next part.


Tape off the perimeters of your nonskid areas with nice radii on the corners and all that. Go an 1/8" larger then the original to establish a clean edge, or even change the shape if you want.


For the next step, you will want some sort of colorant to add to epoxy resin so that you can CLEARLY see to ensure you have an even coating, with no "holidays" or bare patches.



Roll out a very very even layer of this epoxy resin with a small radius foam roller over the taped off nonskid patches.


Taking 2 bags for a 30' boat, cast handfuls of 20/30 silica sand blasting media on top of that very very even layer of epoxy you rolled out. You are not sprinkling here. You are going to throw sand until the deck looks like a beach.


Let that cure. Don't mess with it. Don't try to patch it unless you must.


Vacuum off the masses of sand with your huge shop vac. Don't go grinding it into your fresh paint.


Sweep at the exposed sand stuck in the epoxy, and vacuum some more until very little loose material remains.


OK. What you now have is silica sand (essentially the same material as fiberglass cloth) poking out of a bed of epoxy. It is even and beautiful, but we still need to coat it.


You have two choices: Rolling more epoxy over the top, then painting the non-skid, or my preferred option, which is to paint it out with exterior (has paraffin wax added for a curing layer) polyester gelcoat.


Now Gelcoat is polyester, and polyesters (in any form) DO NOT STICK to epoxy for squat...BUT you have lots of exposed silica to bond to. So, you may now choose a light grey or tan (purple is not allowed I think) *cool* color to contrast your beautiful titanium white paint.


First, pull the tape you used to apply the sand.


Clean up (scraping any tape stuck under edges etc..) and re-tape a little bigger than the rough part, and over the edge of your pretty new paint job. This is a detail issue here, so get that tape stuck down CLEAN.


Roll a coat of gelcoat (molding gelcoat, without wax), then follow up with a second coat after that starts to cure using Exterior (also called "tooling gelcoat" or "wax added") gelcoat.


Pull the tape when the gelcoat has reached the "orangepeel" stage, or it is soft-cured.


Pull all tape and crap off the boat. Rinse with water. Wash with soap and water. Go sailing. Six days well spent.