Gell Coat cracks... Well the whole damn boat.

dieselboy · #1 (**permalink**) 10-14-2009

So my boat is getting to the point where i want to rework the upper decks.

I have two problems , one is the boat is 40 years old and the gell coat has seen better days the second is that someone applied cheep paint over it and its cracking and flaking too.
So do i strip it down to glass and re do it all?
smooth it as much as possible and fill it?
or just go over it?

P.S. these holes are no longer there. I have redone them and they are the best spots on my deck as of now.

Thank you all for your time and for putting up with all my dumb questions.

scottyt · #2 (**permalink**) 10-14-2009

some will say to sand the deck down some then paint with a high build epoxy primer. then paint it with a quality paint. i believe its better to sand then roll on slightly thicken epoxy, using silica as the thickener. this will make a hard solid surface, but it will be hard to sand smooth. so use a epoxy primer over the silica/epoxy and sand that smooth.

i feel that the high build epoxy primer by it self wont stop the cracking from coming back, but the silica will make epoxy hard as a rock.

you could also use a thin glass ( 3 oz ) with straight epoxy over the hull, then fill the weave of the glass with primer or filler. this would give a very crack resistant surface, but also lots of filling and sanding to smooth it out. honestly this is probably the best way short of sanding off all/most of the gelcoat

any way you look at it its lots of sanding

dieselboy · #3 (**permalink**) 10-14-2009

Lots of work , i know.... But i have thought about using a thin coat of Max Bond epoxy/resin over the real tough area's. I have no water leaks as of yet and none of the crack are very deep, there just ugly..lol
The bad layer of poor paint just makes them look even worse.

mitiempo · #4 (**permalink**) 10-15-2009

Epoxy will not stick to the paint already on the deck so you'll have to remove that at least to get to good gelcoat. Epoxy will stick to gelcoat if it is stable as it's really polyester resin with pigment. I'd sand back to stable gelcoat, fill any cracks that are visible with silica thickened epoxy, sand smooth and fair overall with epoxy thickened with microballoons as it's much easier to sand than silica. Then follow the instructions for the coating you have chosen. Paint will not effectively fill the cracks in the gelcoat - at least not for long.
Brian

xort · #5 (**permalink**) 10-15-2009

Are those cracks in the paint or in the gell coat?

georgefmys · #6 (**permalink**) 10-15-2009

Only approach that will work is to sand off all cracked gel-coat. Maybe use chemical stripper on the paint on top of it first. 60 grit paper works fast-if you do apply high-build epoxy after[a good idea] scratches will easily be filled. Keeping all surfaces fair can be tough-it helps to have a selection of hard sanding blocks with profiles that fit your boats molded radius -easy to make from cut-offs of plywood or foam core.

deniseO30 · #7 (**permalink**) 10-15-2009

if your going to use epoxy ... could you not also lay down FG fabric? then it would bond, seal and be crackless. i would also add weight though.

mitiempo · #8 (**permalink**) 10-15-2009

Fabric isn't necessary. Sand the paint off. Grind out any cracks in the gelcoat to a "v" shape and fill with epoxy that is thickened with silica. Once set wash blush off with water and fair any low spots with epoxy thickened with microballoons for easy sanding. Use a wide applicator and try to keep the surface smooth requiring less sanding. All gelcoat doesn't have to be sanded off, just the places where it's loose ot not attached to the glass below it. After the fairing coat is set wash off blush with water. Coat with unthickened epoxy. Wash then sand smooth with orbital sander with maybe 120 grit just enough to get a smooth surface. Then apply paint of choice, preferably a 2 part polyurethane like Interlux Perfection for a long lasting finish. I've done this to my bridgedeck where I moved the traveller and had quite a few voids under the gelcoat and some cracking of it. It now looks factory finished and was easy just took a bit of time. Here's a lin k to West Systems Fibreglass Boat Repair Manual that details this and other solutions. http://www.westsystem.com/ss/assets/...aintenance.pdf
Brian

georgefmys · #9 (**permalink**) 10-15-2009

Looking at pics,no way to only remove individual cracks,it's all cracked! That gelcoat is,or was, done. If it was a boat bottom,or maybe even topsides, rolling on clear epoxy could help ensure a heavy moisture barrier and be easy to apply to large,flat surfaces. But I see it as unnecessary, and way too difficult to achieve good results on deck. Please don't glass over gelcoat! Should not even apply clear epoxy over any gelcoat...if you must,sand it a bit,close one eye, andprime and paint over it. The new work will probably telegraph the old cracks but it may take a while,and surely would still be huge improvement over present condition.

Stillraining · #10 (**permalink**) 10-15-2009

Good Thread ..Thanks for the dumb question Dieseldoy..

OK I too will be needing to do this some day...so what about areas with differing texture..my deck like most is cut up into smaller blocks that have a non skid finish that was molded into the gel coat seporated by lines of wide smooth ones. How would one retain or duplicate that non skid pattern...Im not real keen on a sanded ( as in sprinkeled on sand for traction ) surface..ever fall on one?..you loose a lot of skin.