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Sunfish Hull Repair Help

Drew Kobasa

New Member
Hi guys, I just bought my first sunfish last weekend. It's a 1988. I got a great deal on it with a racing sail, but it has some damage. The guy I bought it from said during the winter wind flipped the sailboat and the impact caused the crack. I've looked through the forums, but I haven't found anything with a fiberglass crack on the hull like mine where the bottom and side meet. Also, I could use some advice on how to repair the little bit of damage(not cracked/leak) on the keel of the boat along with the spider cracks.
I would really appreciate it if you could also tell me what kind of products/tools I should use. I've attached pictures of the damages I'm talking about.
Thanks for all the help!


Kevin Mc

Active Member
That looks familiar! I had a very similar crack on the hull I bought used a few years ago - see the attached photo. I cut out the bad area, removing as little as possible, and beveled the edge around the hole. I used a little spray foam to provide some support behind the patch. If the opening was wider I would have epoxied some wooden slats across the hole on the inside. I applied layers of fiberglass to cover the hole and bevel and sanded it flush once I had a sufficient number of layers. A little paint over the patch and it was good to go - no problems in the 5 years since making the repair.
new hull - 4.jpg


Well-Known Member
Photos #2 and #3 appear to be superficial: sand them away, and/or fill those with West® epoxy.

Photos #1 and #4 indicate structural damage. By sanding, taper away the damaged part, and determine how big to make a patch (for bonding inside the hull).

Cut a 1-foot square of grocery-bag plastic, and tape it next to the damage. Again, using West® epoxy, create a fiberglass cloth patch on the outside of the hull to use as a matching (curved) backup inside the hull. Your newly-created fiberglass patch won't stick to the grocery-bag plastic.

Before it cures, imbed wood or metal "points" in the centerline of the patch: you'll need them to pull the patch against the damaged area. If you forget, you could drill 1/8" holes to attach sheet metal screws, after the patch has fully cured.

Use thickened West® epoxy on the contact area of your patch, and insert it behind the cut-away damaged areas. Use the best means at hand to bond the patch strongly. (Bungee cords, elastic, Cleco fasteners, gravity).

Instructions to complete the hull repairs are found here, highlighted in blue print:
Hull Repair | SailingForums.com
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Drew Kobasa

New Member
Thanks for all your help! I though I would add some photos of the repair. Also, I'm attaching a link to a video on youtube that I thought was really helpful when I was repairing the crack. I have some more photos that I might upload later. The only thing left to do is paint the hull. Any suggestions on type of paint?



I had some hole in my Super Porpoise that I had to patch. The fiber glass patch look pretty similar to yours at that point. I took it further, after sanding it, I used some Bondo to make it smoother. It required a few thin layers and lots of sanding, but you can't see where most of the patches are. I also used fine filler on the hairline cracks in the gelcoat. Again, sanding required and work with thin layers.
For paint I used Rustoleum Topsides over Rustoleum Wood and Fiberglass primer. The primer covered great. The Topsides required three top coats to cover the primer and scratches off if your not careful. I used it top and bottom even though it says it's for above waterline. My boat spends most of its time out of the water so that's not an issue(so far).
Good Luck