gelcoat repairs

hi, I have a '77 Hobie 16. Entire boat is a faded orange color. I love it!

The gel coat is worn off the bottom of my hulls in the middle. I can see the weave of the cloth but it appears that there is a layer of glass over the cloth still. Should I try to repair this by replacing the gel coat? Generally I've heard don't worry about it, so I haven't been. BTW I drain 2-4 cups of water out of my hulls after every sail but nothing major. Again, haven't been worried about it.


The hulls also have a bunch of scratches in the gel coat. The scratches look white against my orange hulls. I've never been one to care much about style points but I'd like to get rid of them if possible. Reading the forum, it sounds like Formula 27 is the way to go? I should try to mix in some orange tint?

thanks

Having just repaired three major holes in my H18 hull bottoms (sad story don't ask), I found that the gell coat spraying was simple and the result great. I only gel coated the bottom six to eight inches of my hulls, thinking that it was my first time spaying the stuff and it might not look good. In the end I wished I had sprayed the entire hulls as it looks great.

I used a gravity feed HVLP spray gun hooked up to a 5 HP compressor. Make sure you use "air dry" additive with the gel coat, or buy gel coat that is waxed. Either of these will allow the gel to cure without spraying PVA on top. My boat is white so I did not have to mix colour so I can't comment on that part of it. Though next time my wife leaves town I am going to gel coat my canoe (she finds the stuff smells way too much to let me do it again while she is home, and I agree the stuff does smell terrible but I wear a resperator and don't smell it). As far as quantity goes, I used one liter to do the bottom of both hulls.

Formula 27 (made by Evercoat) is a polyester based "body putty...filler" for lack of better words. It's quite thick, white, and when cream hardener is added it kicks off fast. I would not recommend trying to add any pigment to tint it, as you will change the chemical properties. Sometimes to get the "white" out of a gouge, all you may need to do is apply some resin to it, (not recommended) or, if the gouge is very minimal, buff it with a good rubbing compound (3M Superduty is a good one). If you want to fill the orange gouges and have the boat look better, try mixing orange gelcoat with colloidal silica, (West Systems 406) or aerosil fibers (basically the exact same thing as 406) and make your own putty. You can get the West Sys 406 from West Marine stores (or have it shipped to you). You will probably need to go to a plastics company for the orange gelcoat...They have color sample sheets just like a paint shop and might mail you one. If you can't find one near you try the one I use..Here's their info.. DMC.....Diversified Materials Co. (San Diego) Phone # is 1 (619) 464-4111 (ask for the sales desk). Good luck, let us know how it turns out.

thanks for the replies. I'll let you know how it goes.

I believe the upcoming July/August issue of Hotline is to have the third part of THIS OLD HOBIE that is suppose to review the BLACK ART of spraying gel coat. I’m looking forward to this. I am planning some gel coat repairs / cleanup for this fall (after sailing season).

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John Latimer
'79 Hobie18 - Magnum
Sail#4854

Hi John...You are correct. The next HOTLINE does have my third article in it. The info should get most most of us doing repairs started on the right track with regards to spraying gelcoat. The article shows one way to spray gelcoat..there is always going to be another "style" or "method" from what I show. As for the gouges to Oahu 16s hulls, they need to be filled first to get everything smooth, prior to spraying gelcoat.

West Marine sells two gelcoat products, one is a "finish" coat that air hardens, the other is a "laminating" product, designed for structural application, which stays tacky to accept additional layers with a chemical and mechanical bond. What most people don't know is that the "laminating" gelcoat will cure hard if you cover it with saran wrap or spay PVA over it, depriving it of oxygen. This will give you more bang for the buck if you only want to purchase one variety.

Also, Marine-Tex, which is usually of a sticky, frosting consistency, will cure smooth and hard if you slick it over with a thumb covered with soapy water. It can also be tinted with the same agents as the gelcoat repair kits. It comes in white and gray, depending on what color you're trying to achieve.

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Sea ya,
Chris Larsen
Co-Pilot of the Hobie Getaway
"The Twins"

~~(\_~~

my gel coat supply guy sold me an additive that they call "air dry". This allowed me to economize as you suggested as I just added that to the last coat so that it would firm up. The previous coats were just straight gel coat and as you say they remained tacky. I don't know what the chemical was in the "air dry" but he calls his top coat gel coat "waxed gel coat" and the stuff I bought he called "unwaxed gel coat". Somehow I doubt it is simple wax but I can say that when the "air dry" came in contact with acetone the "air dry" sure started to look like wax and I had to agitate things very vigorously in order to mix it all together.

The air dry stuff actually has a wax in it. You can buy the wax additive separately so you can use the same can of polyester resin for laminating and then add wax to the last batch for air curing the top coat.

As far as coloring the scratches (or a whole batch of gelcoat), you can get coloring agents from various dealers that can be added to gelcoat, polyester, epoxy, fillers, Bondo, etc., etc. You'll need to experiment to find the right color mix.

Wow- check out the videos on gelcoat and structural repair (at the link above)!!!! Everything you always wanted to know about repairing fiberglass hulls.

Unfortunately, they only briefly mention "air inhibited gelcoat" and don't go into the differences, wax additive, etc.

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Alan
'86 H16, Sail #89057