Alberg 37, 1975, gelcoat cracks above waterline

[Oldsailor27]

Hi there,
I have started to dremel cracks on the gelcoat on the hull above waterline.
There are thousands of them. Gelcoat is quite thick and it looks like the cracks mostly appeared due to the boat sitting under the sun for extended time plus there might have been some banging on the dock in the past.
The fiberglass under the cracks seem to be in good condition accept to showing some light lines on the fiberglass right underneath the cracks. I have tried to grind these likes and they appear to be not deep, just a surface discolouration as a result of water seeping inside.
Anyone who had experience with this kind of problem please let me know what is the best course of action, - should I just v-dremmel the clack lines going a bit to fiberglass and fill the gaps with thickened epoxy or I have to go to extreme and strip all the gelcoat and repair and paint the hull.
Also in addition to old cracks I see in some area microscopic new cracks appearing in some areas of the hull. The thiught of stripping the hull makes me nervous to say the least.
Please let me know what you think.

[Cheechako]

They look to already be grooved for repair? I would buy some matching Gel Coat, fill those up above the surface with a tiny artists brush, let it harden. Wet sand it flush and polish the area. Sheet wax, or even wax paper can be used over it if it runs too much before hardening but it shouldn't.
Final polish with 3M Finesse It and a foam wheel works very well..
I even do this on guitars now after repair:

[jpendoley]

I’d peel the topsides, fair it and paint it. No matter what you do that gelcoat will keep cracking

[Oldsailor27]

Thank you guys.
What is the best tool to peel the topside.
I have seen some guys using gelcoat stripper but it’s really expensive
Bend held belt sender is another option I guess.
I have tried orbital sander and it’s very ineffective.
Any suggestions?

[jpendoley]

Look before you leap. Peeling topsides is a pretty big job. Ideally, you peel it with a gel coat peeler, coat it with a fairing compound like a high build epoxy primer and then fair it. It’s a big job as boat refinishing jobs go.
If you google “ you will see some YouTube’s and the name of two companies will come up-one in Europe and one in Rhode Island. I have the tool from the RI company-it’s a fantastic product and 1/2-1/3 the price of the European one. It captures 99.9% of the waste and can remove minute amounts of gel coat at a time leaving a very fair surface. That helps lessen the fairing required before you can paint.
That said, it’s not for the faint of heart. As with any tool you can damage your boat if you don’t practice on a less critical surface-think an old dingy that you have been meaning to paint. And the fairing will still require long boarding to get a fair surface for paint. The tool will peel a 37 foot boat in 8 hours of careful work and leave a very smooth, but not perfect surface for painting. stripping the gelcoat is the easy part-fairing will make you want to take up another hobby.
Before you consider such an ambitious project be sure those cracks are in gelcoat and not old paint. Gelcoat of that age usually fails in a alligator fashion-you have some cracks that suggest possible stress induced cracking-you’d want to determine why the cracks occurred before you embarked on an ambitious program like peeling. It would suck to do all the work and have the problem reoccur.

[jpendoley]

And a belt sander is a really, really bad tool for the job

[bil56]

what is the average thickness of the gelcoat where you scraped ?

[Oldsailor27]

Thank you jpendole, just a thought of peeling and fairing the hull makes me g to sick in a stomach.

The gelcoat thickness is up to 1/8 of an inch, may be a bit less but wuirevthick.
There are some new very tiny cracks are developing in some areas. Some could be stress cracks, but majority I think due to the sun exposure. All the cracks are on the port side which was failing the sun and there is almost none on the starboard side.

[Manateeman]

We think you ought to do more research on this model as there has been a lot written about more serious issues than gel coat cracks.
Much more serious issues.

[Bowdrie]

Originally Posted by Oldsailor27

All the cracks are on the port side which was failing the sun and there is almost none on the starboard side.

It wouldn't surprise me.
A fiberglass/resin matrix is more flexible than might be thought, and it does expand and contract with big temperature swings.
Gelcoat is basically resin with a lot of filler in it and it has different expansion/contraction rates than the underlying laminate.
The effect you describe is more often seen as the gelcoat thickness goes up. and with the passage of time.
It's similar to the crazing you might see in old "hot rods" that were painted with large amounts of Lacquer.
The steel body "comes and goes", and the rigid lacquer can't accommodate the movement, especially as it ages.

[Don C L]

I have a lot of crazing too. IMO there is no way to bring that gelcoat back to look like new. Time to think about painting I think. Interlux makes a 2-part primer called Primekote which I have seen used on gelcoat crazing and it seems to work well. Looks like you have dug out the crazing so you may need a filler first, I am not sure that Primekote was intended to fill voids that large. I have had good luck with white Marine-Tex for filing. Westmarine sells their own version, which is cheaper, that has worked well for me.

[MarkSF]

Originally Posted by Manateeman

We think you ought to do more research on this model as there has been a lot written about more serious issues than gel coat cracks.
Much more serious issues.

Is it a secret what those issues are?

I just tried searches on this forum for "Alberg 37 Structural Issues" and there is virtually nothing out there.

I do get some hits, with that search term, for Lagoon problems.....read into that what you will.

[MarkSF]

My thoughts in no particular order, and worth exactly what you're paying for them :

Gelcoat isn't structural, it's there to make the boat look nice. The fibreglass underneath is what holds the boat together.

If the gelcoat is failing, obviously it doesn't look nice anymore. The easiest path to get it looking nice is to paint it.

Grinding and filling every crack will be a Sisyphean task.

There are products designed to fair cracking gelcoat but this field is outside my experience.

I can see some old boats around the marina, that have been DIY painted, and they look great.

I would re-phrase your thread "painting a boat with cracking Gelcoat"

[Manateeman]

Sorry for the delay. The shaft log. This is a major. If you can do it yourself, ok but some yards just are not skilled enough. All the bronze rudder bolts. The Edison steering all should be examined. Any soft deck area.
Mark