Repairs to canoe---which resin?

[redbopeep]

We've been using our Merrimack Prospector as a dinghy for our schooner. We love the canoe and have used it lots in the decade we've owned it--and I realize that I need to repair its many small problems.

The canoe is fiberglass laid over very thin cherry ribs. Gunwales, seats, thwarts are ash and cherry. The problem is two fold--first, a few of the cherry ribs have small cracks in them--I've talked to the Merrimack company about how to repair and they suggest simple application of fiberglass and resin patch over the damaged spot. This will be thin enough to not distract from the looks of the ribs. The fellow I talked with about doing the repair stated I should also lightly sand the boat and apply a polyurethane to seal the entire interior if it seems that the resin is getting thin over the ribs. It most definitely is getting thin. The other day we left the canoe sitting upright (it is normally stored upside down on deck) and the dew on it actually caused one of the top areas of a rib to split! Yikes!

Ah, but then the question then comes up "which resin?" The boat was built with a vinyl ester resin according to the sales folks (rather than polyester resin) but I haven't confirmed this with the tech folks there that the sales dude is right. He seemed to not know too much about the older boats, so it may just be that the new boats are vinyl ester but old ones are polyester resin.

OK, I'd planned on fixing it using West System since we have it sitting around and I can use it readily. However--is this OK on vinyl ester as well as on polyester?

Any other materials that I should consider? I figure that many folks here build their own canoes and kayaks so can advise on this matter.

Here are a couple pics of the canoe since I know you guys like pics
All the links are large images

http://farm5.static.flickr.com/4013/...bd0e8007_b.jpg
http://farm3.static.flickr.com/2762/...72b8dd1c_b.jpg
http://farm5.static.flickr.com/4002/...1f3b4676_b.jpg
http://farm5.static.flickr.com/4034/...0aa99726_b.jpg
http://farm5.static.flickr.com/4067/...474ba3c2_b.jpg

[Brian Palmer]

Epoxy will bond to vinylester resin. It should work fine. It has to be overcoated with something with UV inhibitors, such as spar varnish or paint.

Brian

[wizbang 13]

Rib Crackin'Dew!! That some severe weather!!!

[redbopeep]

UV resistance... I have some Bristol traditional amber urethane finish (this stuff) that I've not used on the schooner and I was wondering what I'd do with it...perhaps that will be my UV protection.

Yea, Wiz, I was super surprised when I saw the splitting (along the grain) of one of the ribs. The area that split was about halfway up from the turn of the bilge to the gunwale. Those ribs are very, very thin. I don't have a measurement but we're talking 1/16th" to 3/32" I'd say. Almost veneer.

Thanks for your help

[redbopeep]

another question. I'm getting started on the project today and I note that the vinyl ester or polyester resin is cracking along the edges of each rib and and in occasional locations on the ribs besides the ones I'd seen before. There's a whitish/yellowish haze to it where its cracked away from the wood rib. I can painstakingly scrape this off each rib and then coat with new resin but I'm wondering if vinyl ester resin or polyester resin have the same problems with UV that epoxy does and if that's the reason this is happening? IIf so, should I just make this a bigger project and sand all the resin off the ribs and re-resin them? Big project?

[wizbang 13]

I'm not a canoe guy,but are you using this canoe as a tender from the schooner ? Can it become a bit heavier and a lot tougher?

[Cuyahoga Chuck]

A rib that is only 1/16" thick can't be of much benefit structurally. They could be an arty add on to keep the fiberglass from oilcanning which is common on glass hulls that aren't exceptionally thick or don't have any buttressing. If they aren't needed structure peeling the hull apart to fix them may be alot of work for nothing.

[redbopeep]

We have two tenders for the schooner. This is one. The other one is a 12' Tinker Traveller inflatable that is pretty tough. All the insults the canoe has received have actually been from rocks on river canoe trips. Ouch-y. As a tender we're able to take pretty good care of it. It weighs 65 lbs or a little less. That is an ok weight for a tripping canoe (portaging) which is what it spends its primary life being when it's not one of our tenders on the schooner. It is also a great weight for me to lift it onto and off of the car or schooner by myself. Before we moved onto the boat we had 3 canoes and this was the heaviest. The lightest was a 31 lb kevlar one that we also used tripping but had less weight capacity than this canoe.

If we had someplace to store it when we're not using it for wilderness tripping, we'd have a tougher canoe on the schooner, but alas, we live aboard and have no place to put the canoe besides on the boat or on the car (which isn't a great place to put it when we leave the car for weeks at a time in strange places). We have considered driving cross country and putting it in our storage unit in Maryland (there's room for it there) but that's a long drive from the West coast just to store a canoe! Lastly, we have considered selling it but, well, it's a great tripping canoe.

Here's the pics that shows the ribs. You can't see the edges I'm referring to, but you can see how many ribs there are! The other pics linked above show the canoe in use and I can now "link" to them in this post but I couldn't above for some reason...



















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[redbopeep]

A rib that is only 1/16" thick can't be of much benefit structurally. They could be an arty add on to keep the fiberglass from oilcanning which is common on glass hulls that aren't exceptionally thick or don't have any buttressing. If they aren't needed structure peeling the hull apart to fix them may be alot of work for nothing.

They are structural though very thin. I wouldn't be removing them but rather sanding or scraping the resin off the tops of them to recoat. Today I called and left a message for the canoe company that builds them about this matter. I really suspect it is UV degradation of the resin...but just don't know what the right thing to do is.

[Todd Bradshaw]

The ribs are structural on the bottom on those boats - basically because they have filled the spaces between them with more veneer and then laminated a fiberglass mat bilge cookie on top of the entire bottom, inside the hull. They have basically just made a typical cored bottom (similar to the coremat, balsa or foam cores used in the bottoms of a lot of fiberglass canoes) but one that resembles the look of the inside of a wood/canvas canoe with the faux ribs extending up the sides. Once you get to, or above, the curve of the bilge, the ribs do very little to reinforce the sides, since they are essentially an open-faced sandwich (not glassed-over, just glued-in).

The whitish/yellowish stuff showing on some of the ribs is the coating (resin, varnish or whatever they used over the top of the bare wood) delaminating from the wood, possibly due to age and UV, possibly due to water intrusion. If you really want to preserve this canoe, you will probably want to sand all the finish off of the upper, unglassed portions of the ribs and re-finish them. If the boat gets reasonable care and decent storage, I'd probably sand them clean, lightly sand between them and just varnish the entire interior. If the boat sits out much or sits with water inside for extended periods, then the best bet is probably rollong on a couple thin coats of plain epoxy resin (sticks better to cured polyester or vinylester than more of the original resin will). If you roll it on thin and tip it out with a brush on the rib faces, it will be reasonably smooth and not require much sanding. Then it should be varnished to protect the epoxy.

Owners seem to like these boats and the way they handle, but there is a very good reason that none of the other fiberglass canoe makers have ever picked up on this veneer-ribbed construction - it looks nice, but is a tremendous long-term maintenance and repair hassle.

[redbopeep]

Thank you for your reply Todd. It's a funny thing about this boat--we wanted a Prospector hull which weighed 65 lbs or less and we wanted to spend as little as possible. When we bought it in 2001, the only other Prospectors we found were either very costly or very heavy. This maker was in the right price and weight range and had the added bene of being a pretty boat as well. These days, the brand is much more expensive. I'm amazed, truly, by the cost of the new ones.

We've used it extensively and have taken pretty good care of it. It used to be stored indoors. However, the last 4 years it has lived aboard the boat or on top the car and that has been hard on the gel coat. The interior--this is a recent thing. It usually stored upside down so doesn't get a lot of water sitting on it. Must be UV related to start with.

[coelacanth2]

Straight epoxy might be a little soft. Anaddition of a modest amount of colloidal silica might help in the abrasion - resistance department.

[Todd Bradshaw]

Straight epoxy (varnished over) is tough enough to survive quite well on both the insides and outsides of thousands of strip canoes, so you shouldn't need to add anything to harden it up (or possibly reduce its clarity). As for the gel-coat on the outside, hunt up a bottle of 3M One-Step, cleaner/wax or a similar product from Rule, Meguires, etc. They're wax with a bit of polishing compound mixed in and do a surprisingly good job of removing moderate oxidation and shining-up dulled gelcoat with no more than a rag and some elbow grease.

[redbopeep]

Hey all, I am surely slow. Yesterday I scraped off the resin in a few places where it had cracked (due to a rock pressing in on the outside of the hull or something being dropped onto the rib). A couple of those spots experienced cracking of the rib but not breaking of it. One spot has a broken rib. I will reinforce those areas with 4 oz fiberglass cloth (the kind that surfers use out here in CA, it is woven but lays down very thin and ends up being clearer than the "veil" which is a thin fiberglass matt) and use epoxy resin. Tomorrow it rains so I'm not able to get going on this project again until Sunday or Monday. After repairing those particular ribs (a total of 11 ribs) I'll varnish them but then take a break from the project until I have more time to scrape the resin off the other ribs. I am using a sharpened scraper which doesn't damage the wood at all. With all the curves, I have to hand sand and that takes forever plus it takes resin off the black areas between the ribs and those areas are perfectly fine--thus I've resorted to scraping.

Todd, yesterday I stopped by the auto detailing supply place to get some of the 3M stuff and a wool pad as well as a foam pad for my Porter Cable buffer.