Best way to repair

norcalsail

norcalsail

Well-Known Member
Yesterday, My friend Rick and I brought all four of our collected Sunfish down to the lakeside to work on. We looked at my new, green Sunfish acquisition for chip repair. Rick knows a bit about this having numerous boats of all types. He got out the Dremel and started grinding a channel to add gel coat. Well, he found a soft spot and we decided to grind it out and created a couple of holes that are about a half inch each. These are going to need fiberglass repair, I'm guessing. The gel coat seems pretty thin in this area, overall. I'm hoping for some advice on this issue before proceeding. Should we try to glass inside and out and is there a size/thickness of fiberglass fiber we should use? Also, should we try to gel coat the areas that seem thin? As always, advice and knowledge is much appreciated!
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I'd check for localized "crunchiness" and if none is found, fix with white Marine-Tex. (<$25).

Cover the curing repair with clear plastic film to help reduce the amount of sanding to smoothness.
 
I’d go with this approach. Blind Patch Basics | How to make a blind patch to install inside a hull for fiberglass repair | By Small Boat Restoration - Facebook. A Bondo or similar brand repair kit will come with fiberglass cloth and 2 part polyester resin. For small holes like this Fiberglass cloth is fine. You don’t need a heavier cloth like woven roving.

For a boat with as many scratches as this one has, gelcoat is not worth the trouble. I’d fill the patches from the first step (after they are hard) with white Marine Tex. As LVW says, use a heavy tape or plastic over it to try to get it smooth and minimize sanding. marine Tex is hard when cured.
 

3M Marine Premium Filler​

Green can
Easy to sand and work with
You can paint or gelcoat

Never Marine-Tex
This stuff is hard to sand and most time you will remove more gelcoat
 
LVW said:
I'd check for localized "crunchiness" and if none is found, fix with white Marine-Tex. (<$25).

Cover the curing repair with clear plastic film to help reduce the amount of sanding to smoothness.
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Thank you LVW...
 
beldar boathead said:
I’d go with this approach. Blind Patch Basics | How to make a blind patch to install inside a hull for fiberglass repair | By Small Boat Restoration - Facebook. A Bondo or similar brand repair kit will come with fiberglass cloth and 2 part polyester resin. For small holes like this Fiberglass cloth is fine. You don’t need a heavier cloth like woven roving.

For a boat with as many scratches as this one has, gelcoat is not worth the trouble. I’d fill the patches from the first step (after they are hard) with white Marine Tex. As LVW says, use a heavy tape or plastic over it to try to get it smooth and minimize sanding. marine Tex is hard when cured.
Click to expand...
Thanks Beldar, much appreciation to you and LVW.
 
Are you going to have a "beach banger" as Alan calls it? If so KISS Principle applies. You can spend a lot of time and a lot of money to just scrape all of time and money right back off of the boat during the first launching.

Nowadays we like smooth and one mostly uniform color. in the old timey days we might have slapped a fiberglass bandaid on the hull and gone sailing happily for 20 years. If you look close at WAVE's hull, you might see an ugly but functional and very thick fiberglass patch right below Skipper's butt. I don't think I even sanded the patch before splashing on some Interlux Brightside Blue Glo White.

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This repair is a multi step repair of the fiberglass hull structure (resin/hardener/cloth) and gelcoat (think of it gelcoat as a thick, durable coating that protects the fiberglass from UV and makes the boat purty.)

First we would make a foundation for the fiberglass repair with a Blind hole backer patch inside the hole(s) and let it cure. We use cardboard to hold a piece of woven roving fiberglass cloth inside the hull to create a surface to build up layers on. Thickened epoxy resin SYSTEMS (or polyester resin systems) do a lot of the gap filling inside, Think of the icing between layers of cake, or mortare between bricks. If you used a thin, runny icing or mortar, the cake layers might fall apart.

Now pause to think about the end game, which is the outer coating of gelcoat of paint that protects the fiberglass. For a smooth coating that is fair with the surrounding surfaces, the fiberglass has to built up just shy of your desired coating thickness, otherwise there will be a bump. We also need to make sure that all of the products we use are compatible chemically, meaning resin, fairing compounds, primer, paint or gelcoat. Gelcoat will not stick to epoxy based resin, but it will stick to a dry primer.

Capn Jack always classified paint/gelcoat/varnish as "coatings" that protect wood or fiberglass. He also thought primer as a "bridge" between structure and coatings.

When we say thickened epoxy (or thickened polyester) we are referring to a blend of epoxy resin, hardener and filler (thickener). Different types of fillers are used from soft to hard, soft fillers for easy sanding and fairing, and harder fillers for structure. TotalBoat THIXO for example is a structural thickened epoxy, and so is epoxy based MarineTex. When we sand those hard fillers, we tend to sand away softer gelcoat around the repair faster than the hard bump on resin.

Then we build up layers of 4 oz fiberglass cloth just shy of the surrounding original hull.

Then apply softer fairing compound to get the surface fair.

Prime.

Paint. Paint is easy. Bare bones minimum for $ and time, think Rust-Oleum rattle can Semi Gloss White (Credit Alan Glos). Spray another can as needed.

Now gelcoat is much thicker than paint, and it might have to be sanded and buffed to get the desired finish. We have not tried gelcoat as most of our restos would have needed a LOT of gelcoat.
 
signal charlie said:
Are you going to have a "beach banger" as Alan calls it? If so KISS Principle applies. You can spend a lot of time and a lot of money to just scrape all of time and money right back off of the boat during the first launching.

Nowadays we like smooth and one mostly uniform color. in the old timey days we might have slapped a fiberglass bandaid on the hull and gone sailing happily for 20 years. If you look close at WAVE's hull, you might see an ugly but functional and very thick fiberglass patch right below Skipper's butt. I don't think I even sanded the patch before splashing on some Interlux Brightside Blue Glo White.

View attachment 56684

This repair is a multi step repair of the fiberglass hull structure (resin/hardener/cloth) and gelcoat (think of it gelcoat as a thick, durable coating that protects the fiberglass from UV and makes the boat purty.)

First we would make a foundation for the fiberglass repair with a Blind hole backer patch inside the hole(s) and let it cure. We use cardboard to hold a piece of woven roving fiberglass cloth inside the hull to create a surface to build up layers on. Thickened epoxy resin SYSTEMS (or polyester resin systems) do a lot of the gap filling inside, Think of the icing between layers of cake, or mortare between bricks. If you used a thin, runny icing or mortar, the cake layers might fall apart.

Now pause to think about the end game, which is the outer coating of gelcoat of paint that protects the fiberglass. For a smooth coating that is fair with the surrounding surfaces, the fiberglass has to built up just shy of your desired coating thickness, otherwise there will be a bump. We also need to make sure that all of the products we use are compatible chemically, meaning resin, fairing compounds, primer, paint or gelcoat. Gelcoat will not stick to epoxy based resin, but it will stick to a dry primer.

Capn Jack always classified paint/gelcoat/varnish as "coatings" that protect wood or fiberglass. He also thought primer as a "bridge" between structure and coatings.

When we say thickened epoxy (or thickened polyester) we are referring to a blend of epoxy resin, hardener and filler (thickener). Different types of fillers are used from soft to hard, soft fillers for easy sanding and fairing, and harder fillers for structure. TotalBoat THIXO for example is a structural thickened epoxy, and so is epoxy based MarineTex. When we sand those hard fillers, we tend to sand away softer gelcoat around the repair faster than the hard bump on resin.

Then we build up layers of 4 oz fiberglass cloth just shy of the surrounding original hull.

Then apply softer fairing compound to get the surface fair.

Prime.

Paint. Paint is easy. Bare bones minimum for $ and time, think Rust-Oleum rattle can Semi Gloss White (Credit Alan Glos). Spray another can as needed.

Now gelcoat is much thicker than paint, and it might have to be sanded and buffed to get the desired finish. We have not tried gelcoat as most of our restos would have needed a LOT of gelcoat.
Click to expand...
Thank you Signal Charlie. I'm going to watch your "blind patch" video and go from there. I really like this green, '69, Sunfish. It's all mine, I paid $200 for it and bought $200 of parts (Intensity practice sail, halyard, and a few other things), and I am hoping to have it for many years to come.
 
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I was over at Rick's today, and he knows more about this repair than I do. We ordered Thixo and two kinds of fiberglass cloth. One is 1708 and structural for the inside patch. We ordered another kind for the exterior that has more cosmetic properties. Rick has a lot of primered gel coat. So when the stuff arrives, we are going to turn those two holes in to one, do the blind patch, do an exterior patch and gel coat it. He also wants to sand and gel coat over some thin spots. When that is all done, we are going to buff out the deck. It should be ready to sail in another week and a half. I'll post photos of the finished product. The boat's a beauty. Today is a nice day here with a good light breeze. I'm sitting here in the boathouse watching Rick's flag wave and am getting ready to take the Oldfish out. Still love my "77 Sunfish.
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