Wenonah Kevlar skin coat repair/refurbish advice?

[dogbrain]

I'm curious if anybody has made significant repairs to a Wenonah skin coat kevlar boat, but mostly curious about long-term results? I am doing repairs of over a dozen of these canoes this winter. They have been literally ridden hard and put away wet for a number of years, with some much worse than others.

The list of repairs needed for these canoes includes cracked foam ribs just above the foam core, various rips and tears in the bottom and sides, old repairs that need to be redone and in a few cases the skin coat has degraded to the point of the canoe needing a recoat of resin and possibly even a large patch of glass over soft/fuzzy kevlar. All of the canoes have the big ugly kevlar skid plates installed, and those have done what they needed to do and are in fine shape. I have done a few minor repairs on canoes like these in the past, and have had good luck using epoxy with kevlar and s-glass patches. Those canoes have gone out in the world with the repairs but I have no idea about their long-term survival. I told people that the epoxy needed to be varnished for the long-term, but I doubt any were.

An online search finds people doing repairs as I did with epoxy, and some using polyester resin. Wenonah suggests using polyester resin for repair, especially if I have to re-coat the bottom of a canoe, or patch a large area with new glass. I think these boats were built using polyester resin, so that makes sense.

Now for the Questions: Is it actually a good idea to use polyester resin for these repairs? The advantage of polyester seems to be the compatibility with the original material as well as quick cure time and the fact that polyester is a bit more stable with UV exposure, meaning no varnish. What are the downsides of using polyester? I’ve read about bonding problems as well as possible long-term cracking and peeling, but the stories appear to be mostly second hand. Epoxy adds time, cost and the need to varnish everything eventually. I'll definitely do some small repairs to get the feel of the polyester prior to doing anything large. Any suggestions from the canoetripping crowd?

Mark

 

[memaquay]

Don't know about polyester, although if it is recommended, you will save lots of money. I have redone a couple of these boats, we currently have one in need of work at the shop. I sanded the bottom, applied patches where needed and recoated with two thin coats of epoxy, rolled on. Then I paint them with rustoleum. No more need for varnish, ever.

 

[Mike McCrea]

I am surprised that Wenonah uses Polyester resin, and would have expected Vinylester, but if your contact at Wenonah was Alison and she said polyester, well, she knows her stuff.

I would still use epoxy. In part because I already have it, and don’t like the fumes and odor off polyester. I have never used Vinylester resin, and expect the fumes/odor is similar (or worse).

I have refinished one clear coat Wenonah, a well worn Revdezvous. Washed and wet sanded the hull, taped the gunwales, rolled and tipped a coat of West System 105/206, waited a week for that to cure, wet sanded and re-taped, rolled and tipped a coat of varnish.

The Rendevous looked like new, and now some years later still looks very nice.

If it is clear coat I would not paint it. A possibility would be using a UV protective hardener like West special clear 207, which has some UV inhibitors. And then I’d probably still varnish over top.

 

[Clint]

@dogbrain This is different from the skin coat Wenonah that you have but, I am interested in this thread. Here is why. I purchased 2 Wenonah canoes last year (Solo Plus and a Whisper). Both have a gelcoat. Both have what I think is really bad spider cracking along with gelcoat flaking off in places. In those places it is clean all the way to the fiberglass. The Solo Plus has had some damage done to it and repaired. Where the repairs have been made the gelcoat is cracking and flaking off also. In saying all this, the gelcoat seems to be pretty soft and easy to sand off. Wondering if I can just sand back to the fiberglass then do a skin coat of epoxy. They may not need anything. For now they are just being used as often as possible and enjoying them. I like the Solo Plus so much I may and try and make a carbon copy like others have done on different boats.

 

[dogbrain]

Mem and MIke. Sounds like epoxy will work fine, so I may consider going that way since it's something I know about. Raka makes a UV inhibited epoxy, which might be a way to go to avoid varnish or paint. I have so many boats to do, and I don't have room in the heated shop to hold on to a boat for a week waiting for epoxy to cure so I can varnish. I'm still really curious about the polyester resin though. The 2 hour cure time is really enticing! As far as the fumes, I wear a respirator and I can vent while doing the work, crank the heat and get out of there during cure time. The boat can then go out in the snow to off-gas. I'll try to contact with Alison at Wenonah to get some first hand info. I'll post what I find out back here so there's a record for the future.

Thanks so much, Mark

 

[dogbrain]

@dogbrain Wondering if I can just sand back to the fiberglass then do a skin coat of epoxy. They may not need anything. For now they are just being used as often as possible and enjoying them. I like the Solo Plus so much I may and try and make a carbon copy like others have done on different boats.

I guess it depends on how extensive the cracks are and how easy it is to get the gelcoat to flake off. I don't know about trying to sand it all off. That sounds like a chore, especially trying to not sand too deep.

 

[dogbrain]

Just talked to Susan at Wenonah for a while, who was extremely knowledgeable about the construction, repair and everything else about their skin coat boats. She said they are/were made with either vinyl ester or polyester resin. Wenonah uses polyester resin and fiberglass exclusively for all repairs inside and out. Polyester will bond with vinylester resin. My first patient in this endeavor is a 23' Minnesota IV canoe. It is still warm enough around here to do repairs outside. Since I have kevlar, I think I'll use it on the high stress points like ribs on the inside and 5 oz. s-glass outside.

Mark

 

[Mike McCrea]

Mark, I can’t imagine the amount of effort, elbow grease, sanding pads and dust to remove a full hull’s worth of gel coat. Any areas left behind and you might as well just be epoxying over gel coat, and getting it all completely off without cutting into the fabric below, just. . . . .just. . . .no.

I would lazy man likely debride any loose gel coat, fill with thickened epoxy and sand fair, then roll/tip top coat the entire bottom with epoxy. And then probably paint it to cover any fugly fills, patches and repairs.

Epoxy will adhere fine to properly cleaned and sanded gel coat. A UV inhibited resin would eliminate the need for a varnish coat or paint if the aesthetics are acceptable, and would make any (possible) future repairs epoxy-over-epoxy easier, without sanding away the varnish or paint first.

I used polyester resins many moons ago, and didn’t much care for them. YMMV.

Looking forward to updates and photos as you tackle this refurbishment.

 

[stripperguy]

Mark,
I worked quite a bit with polyester and vinylester resins, they're no different in terms of working with them.
Both are much stiffer than epoxy resin, and this leads to cracking, as there is little "give".
If you're doing a large area, be very careful moving your wet line along...the resin can easily kick along the line as you switch to the other end of the wet out. This could leave you with a partially wet out laminate that will be impossible to stick down when you come back to it. Those resins are very temperature dependent, and can run away in the pot before you know it. The catalyst MEKP, is quite hazardous, handle it very carefully and wear protective glasses.
Also, those resins will need a finishing wax added as the air will inhibit the cure at the surface, and...if you've used a finishing resin (with wax) and need to add another layer, you need to completely remove that finishing wax in order to have an adequate bond to the previous layer.

With all that said, it is nearly 1/3 of the cost, and it can make for rapid laminating.
Myself, I would just use RAKA epoxy and be done with it.

 

[dogbrain]

Mike, the gelcoat boats aren't mine, I was just answering a question from Clint. I agree though, I wouldn't consider removing gelcoat.

SG - I'm only doing small repairs and laminating new glass to small areas. The entire boats might get a coat of resin to seal the kevlar, but that's up to the owner. The 3m/"Bondo" brand polyester resin directions don't say anything about adding wax or cleaning wax before applying more resin or gelcoat. Full cure in 2 hrs and you can add more after a light sand. The word "bondo" makes me cringe when thinking about boat repair. I plan to do some testing before I commit to using it.

 

[Mike McCrea]

The word “Bondo” in boat repairs make me cringe too. And, back in the day of using auto-store purchased poly resin and E-glass, I did use it. To my regret.

I suspect there are better poly resins for boat work these days, but if Bondo is still Bondo I’d rather use JB Weld or the pastier PC-7 epoxy putty, or, ahem, thickened epoxy or G/flex for gap filling repairs.

You know I can’t resist a story. Friend Dave was a master of disaster, and a master of covering up his disasters. He backed his Ford Aerostar into a cliff edge at a no shoulder road-side take out. Oh no, the missus was gonna be pissed.

We brought it back into my shop. Dave packed the dent with Bondo and called the wife to say he would be late. Then, later that same evening, he sanded the Bondo and spray painted it a matching white. Next morning, before the missus awoke, he brushed the two red pin stripes back on top to complete the repair.

Anita never suspected a thing.

 

[Cheeseandbeans]

Automotive fillers have come a long way in recent years. I have used Evercoat Everglass filler on damaged corvette composite panels with good success. It has Kevlar strands in it, it is sandable, flexible, doesn’t shrink, paintable, and waterproof. I have never used it on a boat, but have a Kevlar hull that needs chips in the gel coat filled and am tempted to try it. I would stay away from any Bondo brand product- junk in my experience.

Bob

 

[deerfly]

probably overkill for what you are doing but will share for information and consideration purposes. I've done quit a bit of fiberglass boat repair and restore over the years and currently have a 1977 20' and 1978 23' Seacraft boats that I'll be restoring in the coming months. Until about 10 years ago I always matched the hatch so to speak. If I knew oem used polyester or viynlester systems then that is what I used to repair/restore.

These days unless I'm doing relatively small blended repairs I use epoxy based system to recoat entire surface. I start by sanding the whole piece with 40grit or 60 grit depending on how much the gel coat is damaged/oxidized. If there is major or extensive damage I will feather grind into to the glass around all that and repair with epoxy and glass build up then fair with epoxy fairing putty. Next I will barrier coat entire surface with a few coats of devo bar rust 235 or facsimile (I think jamestown has a house brand of barrier coating). You need the barrier coat to prevent blistering under new topcoat, its the biggest mistake most diy'rs do when restoring a base coat/top coat system over gel coat. Next 80-100grit sand the barrier coat to prepare it for more epoxy fairing followed by 2-3 coats of compatible top coat primer. Then clean up the little stuff with glazing putty and light sanding before topcoat.

Expensive, but I pretty much just use awlgrip products this kind of stuff any more. This of course is fiberglass boats, consoles and bait well's etc. So lots more material to work with vs a thin skinned canoe, but if you're repairing a small fleet of gel coated canoes that need some deep repairs it might make sense to do barrier/base coat/top coat thing depending on the quality and durability desired.

 

[goonstroke]

...
Myself, I would just use RAKA epoxy and be done with it.

That's what I did when I added a new underbelly to my '84 kevlar skin coat Wenonah C1W. I can't speak to the truly long term, but I have 4 seasons on that boat, hard use and stored outside, and so far so good. I find the Raka UV inhibited epoxy to be easy to work with, and I now use it for more or less everything, but usually with fast hardener -- Raka slow is really slow, even if you live in the South.

 

[dogbrain]

Thanks Deerfly. These boats are skin coat, not gelcoat. It got confused up above when someone asked about gelcoat boats, but hopefully your comments will help them out. The skincoat boats are essentially just fabric and resin with no other coating. The resin erodes over time due to UV and normal wear and tear until you're left with just kevlar fabric that is barely waterproof.

I've gone back and forth on this, but I'll go with Raka UV epoxy. It sounds like there is a reasonably good track record using epoxy for these repairs. Goonstroke, comments from a few other people and yours put me over the top on that plan. Thanks, Mark

 

[deerfly]

no worries Mark, I thought the canoes in question were gelcoated and just sharing my 2 cents on epoxy repairs over polyester as it were.

As fer RAKA UV I use it a lot, very happy with it on all points. My Northwind is UV RAKA on the deck.

 

[Clint]

Sorry for getting the thread off subject.

Thank you for all the answers on the gelcoat.

 

[dogbrain]

No problem Clint, there’s a lot to learn about people’s actual experience with all these different resins. I hope you got an answer to your questions. Mark