Let me start by saying that I’m not a fiberglass guy and this is just how I did the repair. I don’t own a repair shop or claim to be a professional. We good? Cool. OK, so have you ever had an incident where your ski has had a bit of an owie? Well if you have a Kawasaki, modern Yamaha SuperJet or any other watercraft with gel coat this article will show you how to fix it.
The ski I am working on is my own 2023 Yamaha SuperJet which had some gel coat shaved off from making contact with the trailer bunk bracket. The damage was on the bottom, near one of the chine’s on the hull – not what you’d call an easy spot. So let me say, if you can fix a spot like this, you can certainly fix any flat part of your hull.
To make this repair you will need a gel coat or fairing compound. I personally use the Evercoat brand. You can get it at most marine supply stores and even some hardware stores. If you use a neutral gel coat you are also going to need a pigment for the gel coat to blend in the repair.
You will also need sandpaper, acetone, painters tape or masking tape,g loves, something to mix the gel coat (or filler), a respirator and some rags (or no-lint paper towels). If you are using non-thickened gel coat you will also need a silica powder, which will thicken the gel coat so you can use it as a filler, which you can also get at most marine supply stores.
The first step is to wipe the damaged area with acetone to remove any grease or contaminants. It has to be squeaky clean or the new gel coat will not bond properly. Next, use the painters tape to mask off the surrounding area that you don’t want to get gel coat on.
If you are using a filler like Evercoat’s Formula 27 or a pre-thickened gel coat paste, all you have to do is mix the product and hardener (and add pigment if it’s a neutral gel coat) in the ratio that it says on the back of the can, which in my case was 12 drops of hardener per ounce of gel coat. If you are using a non-thickened gel coat then you will have to put on your respirator and add some silica until the gel coat gets to a mayonnaise-like consistency.
Once you have the gel coat and hardener mixed together, use a putty knife to force the gel coat or filler into the repair area. Be thorough about pressing it in or you run the risk of having an air pocket. I used my fingers (with nitrile gloves) to shape the gel coat. If you are using regular gel coat you have to cover it with a piece of Mylar or wax paper (look what it says on the back of the can to know what to cover the repair area while curing).
Curing time depends mostly on ambient temperature. The colder it is, the longer it will take. In my case, in a 65-degree temperature controlled garage the gel coat took around 2 hours. Once cured, it is time to sand and make that gel coat smooth. If you are doing this repair on a part of the ski that is flat, use a sanding block.
Unfortunately, I put the gel coat on a little too thick. I just used 80 grit sandpaper because I also forgot to put the pigment in the gel coat so I had to put a coat of white paint over the repair. In most cases, you should just be able to start with 120 grit, then 400 grit and finish with 600 grit. If you paint over the repair area, apply two to three thin coats instead of one thick coat. If you try to do one thick coat it will run and you will end up with a big mess.
After the paint is dry, wet sand with 1000 grit and then buff with some rubbing compound. If you use a gel coat thickened with Silica powder or if it’s on the underside you can skip the painting step entirely. Just apply a coat of your favorite wax and you are done. Save yourself $500-plus dollars by doing this yourself once you understand the process of it it is super easy.