Hull repair substance?

E

easy does it

Member
Getting home from picking up my new boat (2004) I noticed a hunk gone out of the hull about the size of a small walnut. It is where the boat hits the roller on the ratchet up front. Ugly ..Ouch! maybe I tightened it to much on the trip and it looks like it may have been repared before so I want to do it right this time? I would probably use some J and B weld ..never let me down yet but it seems there must be a better idea? Help! on a good note after driving 5 hrs I got a flat tire in front of my house backing in the R.V. pad...what are the odds ...father Neptune? Angeles?
 
You need to grind out the damaged area and feather it back several inches. Then if it is into the glass laminate use multiple overlapping layers of fiber glass cloth and polyester resin. Grind it smooth and once it is fair, coat with gel coat.

This is not an eaiy to do job by a DIY and very difficult to get it to look perfect. Pros can make it look perfect so you may want to find a boatyard who can do that for you.

But if you don't care about perfection and the chunk is just gel coat, then use Marine Tex which is a thickened polyester gel coat patching compound.

David
 
thank you so much. No it goes in maybe an inch, can't imagine what would have caused it in the 1st place. Is the front not meant to be tight against the roller? I just cant pay anyone to do something I am able to do ...the older I get the more of a curse or a blessing this is!? So I am looking forward to learning about my boat and how to fix it. I grew up on surfboards so really this thing is just a big surfboard to me...ya I know....
 
Grinding and feathering sounds good, but if you don't care so much about a perfect finish, this will take < 1 hour overall.

PC Products 160114 PC-11 Two-Part Marine Grade Epoxy Adhesive Paste, 1 lb in Two Cans, Off White
Sold by: Amazon.com Services, Inc.
$14.66

This is amazing stuff.

Just mix 1:1, it will start as a thick paste that you can just form into the hole. It is incredibly sticky. After forming into hole, I usually cover with plastic wrap and mold to the shape I want with mu fingers. The plastic wrap initially sticks like mad, which is fine, since after it dries, it peels right off with a glossy, smooth finish. The color is slightly different than the C-dory hull, but it is quite hard, durable and completely waterproof. I also use this to seal the holes through plywood or balsa (like C-dory) cores by drilling out holes to a little larger size, and then either forming it around the inside of the hole edges (large holes) so the balsa is completely covered, or filling flat, then redrilling so there is epoxy all the way around with no balsa showing. You may find holes through your deck that aren't sealed, which is a bad idea, as water will enter and can rot the wood core. This stuff is hard, durable and waterproof. I go over the entire hull every time I pull the boat, because I often beach it and my hull gets nicked too.

You can sand it if appearance is important to you. I don't.
 
Easy Does It,
The option that I choose for quality repair and future value of my boats is to hire a fiberglass repair expert. Yes, DIY is not tough to do and the repair will likely be sound, but it WILL always bug you, unless you are using your boat for commercial crabbing of fishing.
My C-Dory had a ding on the chin about the size of a quarter, spider cracks below the door and aft of the port-potty location and a chewed up edge on the swim platform. All of these were on the boat when I purchased it, but I finally took the time to have the repairs done locally by a fiberglass repair guy. The repairs are unidentifiable and the cost was about $350...
 
I believe I have the same ding, near the bow roller. I'm guessing this is from pulling the anchor in but it could also be from fetting the boat back on the trailer. Our used boat came with it, and the previous owner had filled it with marine tex.

I hate it, and it drives me crazy. I plan to use a dremel tool to grind out all the marine tex and fill with thickened epoxy and cloth. Sand it smooth and cover the repair with gelcoat, and sand with very fine sandpaper until it looks as good as I can get it. I'd hire it out but I enjoy the process and developing a new skill.

So as someone who already has the marine tex patch, that definitely does not match the gelcoat color, I'll caution against this fix. Also gelcoat will not stick to marine tex.
 
PaulnBrianna- You have indicated gelcoat does not adhere to marine tex ( a epoxy base ). What is different about filling with thickened epoxy and cloth?
It is a epoxy base.
Much is talked about using thickened epoxy. Gelcoat is a different base, it does not stick to epoxy.
There is a capatibility issue.
 
You are right, I had not thought that far ahead. Using a traditional poly with cabosil will have a more predictable outcome. Thank you for steering me straight before I got carried away and had to do it twice.
 
Easy Does It,
Based on a lifetime of building and repairing surfboards and some limited experience of repairing fiberglass on boats I would recommend using a good grade of marine epoxy (along with glass cloth if the existing cloth has been damaged). Epoxy makes a much stronger mechanical bond than polyester resin. Polyester resin works well for the original lamination when consequtive layers can be added before the previous coat(layer) has completely gone off (cured). If added before the previous coat has cured, new layers form a chemical bond and become essentially a single single thicker layer. On cured polyester resin, epoxy forms a much stronger mechanical bond.
I recommend you go to West Systems Epoxy web site. They have a wealth of information and videos on doing fiberglass repairs including using gel coat over epoxy. They also have a great customer service department with really knowledgeable people who can answer questions.
Using various resins is not that hard. There's no reason to avoid doing repairs yourself if you are careful. West Systems Six10 Epoxy comes in a large tube used in a caulking gun and comes out in the correct proportions without measuring. You can also add a tip to the tube which will mix it as it comes out. If you don't use this tip be sure to mix your resin thoroughly. Six10 is an interesting viscosity that is stiff enough to not sag in vertical or overhead situations but also be used to wet out fiberglass cloth. Resins are hazzardous Be sure to follow all safety practices and always wear rubber (disposable) gloves.
 
Polyester gelcoat does NOT adhere to epoxy.
Repairing a cosmetic issue with an epoxy ? Now you have trouble making the cosmetic finish coat to blend into the surrounding area.
Boats ending up with spots of epoxy that can not be finished properly, because people are confused with the hole filling trend on this site.

If I was going to repair a 1 " gouge, the repair would start by grinding a tapered dished out area 3 to 4" in diameter, filling with layers of polyester resin and chopped mat ( proud of the surrounding area), sand back down to flush, then spray gelcoat mixed to match color of surrounding area.

I do not believe most DIY would dare to grind out the area to begin with.

In a lifetime of rebuilding boats, never have used epoxy. Then I have never owned a painted boat.
 
I'm a rebuilder of old sports cars and old airplanes and a couple of fiberglass airplanes. Lots of experience with glass repairs. So I'm a super DIY, but if I had great pride in a boat with a chunk missing, I'd definitely go find an expert in such a repair. Professionals can make that problem disappear so that no one will spot it. It will be out of your brain. If you do a typical DIY, it will sit in your brain forever and haunt you and you will sell the boat so you never have to think about that less than perfect repair.
 
I repaired all the holes left after I moved the swim-step from starboard to port. I used the above procedure that was taught at the old factory. The repair(s) itself is pretty easy.

Most difficult part, just like cars, is blending the gel-coat (like auto paint). Definitely a skill involved. I did it using a Preval kit with thinned gel-coat I got from the factory. On the first try, I did run into an issue with the gel-coat having a reaction which did not allow it to dry, but only on the patches. I wiped it down with acetone, re-sanded and re-painted. Once that was done, it dried properly. Still don't know what caused the reaction. Pics in my album.

It was not perfect but once I wet-sanded/buffed it the patches are pretty much imperceptible. One is a tad bit "thin" on the gel-coat but that's because I only had a limited amount left and once I sanded/buffed, it showed thru.
 
san juanderer":1f1m1gn6 said:
Magic Fix for the DIY !
Presto and it all looks perfect.
Click to expand...

:lol: Like the magic scratch fixer for painted cars...WITH clear-coat! Uhm, no...


The guy at Boatworks Today does some cool stuff. I watched the video where he used an old hatch lid to make a mold then made new hatches. He made it look easy.
 
There is no question that epoxy makes a secondary bond far better than polyester resin. Vinyl ester resin has a secondary bond between epoxy and polyester, and will have a better bond with Gel Coat. Yes, limited areas one can get good bonds with gel coats--and there area some tricks. Some use a "tie" primer.

I use epoxy when repairing a structural part, such as a hole in the bottom of the boat. But there is no problem with the strength of polyester when doing a cosmetic repair--that adherence is just not needed. I personally prefer to work with epoxy, but I suspect I have been working with fiberglass and polyester resin for longer than anyone else on the site: since I was responsible for the wooden boat repair at Camp Fox, Catalina Island, in 1952 when Glasspar left a half a dozen 12 foot fiberglass skiffs at the camp to test them out. They left me a gallon of resin, some MEKP and glass, mat and cloth, plus a 15 minute primer. I have built boats, as well done many repairs, including extensive repairs on boats with osmotic blistering.

You will find that virtually all good professionals will prefer to use only polyester products for a gel coat repair. Many will do so for full structural repairs also. The professional winces when they are brought a boat to repair which has had epoxy used--it will have to be all ground out for their repair.

I also second those who suggest that a good professional will get a better match than all than the most seasoned amateur. Matching white gel coat is not easy. You need pigments, a little brown, yellow and blue to get the correct C Dory match.

The depth of the void, will dictate if you will need to grind out a large area, or if just a limited repair will be fine. If you do have to lay up multiple concentric circles of mat/cloth to rebuild structural strength--then definitely grind. But if it is just a small area, where you can fill with chopped strands, and resin--then you may have sand a limited area. I would caution about ever using a substance such as "Bondo" on boats...not a good idea. Although I have used a thickened polyester as a fairing substance, I would not use it to fill a void. A true void needs fabric support.
 
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