A question on Gel Coat Cracks

[Snookerd]

I've been noticing some cracks on the deck of my 18' where the deck meets the side. Major concern? It looks like stress areas. The cracks are only hairline size, but they are in lengths of 10" or so and in 5 different spots. What's the deal on grinding and filling vs. glass repair to stop the problem for good? What the heck! [img]images/icons/mad.gif[/img]

[Standing Room Only]

My 18 had cracks on the back portion/top where the stern boxes met the sides. The Fiberglass was broken -- so ground our and reglassed -- it is stronger than it ever was. Other parts were from the previous owner slamming a dock -- some were grind and glass, some just got dremeled out a bit and then had epoxy resin and microfiber fill put in, sanded. Small ones just got epoxy and sanding filler. Happens, and an real easy repair.

[Snookerd]

Thanks Standing Room Only. I intend on my 18' to be my usable boat when I get that future$6,000 23' that needs the total overhaul. I want the 18' to look good and function good while I spent most of my life rebuilding the future 23 with twin 200's on a floatation bracket.

[SECF3114M73J]

I was told by a professional glass man that a lot of gel cracks happen because the gel is applied to thickly. He said when the gel is sprayed on it will settle in the inside corners and gets to thick to flex with the hull . Says gel should be between 6 and 10 mils.

[abl1111]

I have a few gelcoat stress cracks on my 23' Tsunami on stern topside, near fishboxes.

I was hoping to just scrape the cracks out, fill and gelcoat. This is a high stress area. Will the cracks just re-appear ? How do you ascertain whether they are into the laminate or not ?

[Standing Room Only]

When you dremel the crack a bit, if the glass underneath is 'white' rather than the dark amber, a good chance the glass itself is cracked. If you just fill in the gelcoat, the cracks will comeback as it flexes. Be careful about using filler where something structural -- like biaxial glass -- should be used. If it is a narrow crack, grind into the glass a bit with the dremel to provide a good seating, and then use the Epoxy and microfiber. If it is a whole network of cracks or worse, then use the grind and glass method. I had a ton on my boat because the previous owner let it beat up on a seawall for a time. Never broke the hull, but I had some star cracks from point impacts at the waterline, as well as gouges in the gelcoat.

One thing about gelcoat is that it flexes at a different rate than glass, and it is more brittle. Just gelcoat, and the cracks will come back. At a minimum, you will need to make the crack wider with a narrow dremel, fill with epoxy/filler, then sand and regelcoat. Anything else is a bandaid and cracks will appear again after awhile. The process can be accelerated if you add too much hardener to the gelcoat -- a fast cure makes it more brittle than you can imagine.