Thanks
I saw that CLC has the West System peel ply. Is it better than the generic nylon that Sweet sells?
CLC is a bit further drive. But I was planning a trip out to Annapolis anyway to hit up Velo Orange for few bike parts, so maybe I’ll get the peel ply there. The same guy started both companies, incidentally.
repairs not going so well
I finally got around to taking a crack at this canoe repair (pun not intended). So far, not good. I was hoping to not mess with the interior, but when I was beveling out the crack, I slipped and went all the way the hull. I found that the foam core was indeed crushed under the cracked abs, so I went ahead and drimmeled out all the crushed and soft foam. But now I have a two inch long oval hole in the bottom of the canoe. Too big to slap a little g-flex in, so I think I’ll need to do an interior patch afterall. So should I:
a: tape some wax paper to the inside of the hole and layer up the g-flex on the exterior, then patch the interior with Dynell or glass?
or
b: put the Dynell/glass patch on the inside first, then do the g-flex patch on the outside?
Either way, I’m going to finish up the repair with a Dynell skid plate, so I don’t think I’ll need an exterior patch over the g-flex.
My approach
Would be to start on the inside and work my way out using multiple layers of crisis crossing fabric I would use glass on the inside as a backing for thickened Gflex.
Hopefully Pblanc will chime in as he’s experienced with this stuff.
For holes in the canoe another product worth looking at is 3Ms marine adhesive sealant, sold in a caulk like tube-5200. About 20 years ago(before Gflex) I used it to fill a hole in my OT Tripper, which revealed itself as I was doing a Kevlar skid plate repair and, like you, my efforts punched a hole in the damaged area.
The 3M 5200 worked just fine. Had enough flex in it that it didn’t crack when the canoe was put to use on the water bouncing off rocks. I used glass as a backing on the inside for the sealant to bond to.
Today thickened Gflex, glass, and Dynel may be all you will need. Perhaps unnecessary to state, but whatever your choice it will be important that the added fabric overlaps onto the exiting hull at as many locations as you can so the hole doesn’t pop open.
thanks
Okay, that’s sort of what I was thinking. I’ll work inside out. I’d kind of like to minimize having to buy a bunch of different materials, so I’d probably rather use dynel for all the patching, but when I get over to Sweet Composites I’ll ask them about it.
Suggestion
I would use glass for all the structural part of the repair. I’m no fiberglass expert but it seems s-glass gets high marks from many folks for adding strength to your repair. I don’t think Dynel will do as good a job adding strength.
Dynel I would use on the outermost layer(s) as it is extremely abrasion resistant. With a fg/epoxy underlayment providing strength the Dynel will hold everything intact from abraiding away.
noted
thanks, I’ll keep that in mind.
a photo would help
– Last Updated: Sep-29-15 10:30 AM EST –
If I understand correctly, you now have a sizable void in the Royalite extending to the interior that is dished out toward the exterior.
If that is approximately correct and you have not already done so, I would bevel the intact Royalite at the edges of the void at a pretty shallow angle before doing anything. That might seem "wrong" because you are removing good material and making the exterior hole bigger, but it will provide a much bigger bonding surface for your epoxy and fabric, which will make for a stronger repair.
I agree with waterbearer that filling a sizable void with epoxy/fabric composite will be much stronger than using epoxy alone. Epoxy blended with silica powder is great for filling in small voids like cracks, but a big mass of cured epoxy unsupported by cloth is going to be more brittle than epoxy supported by cloth. I would also use fiberglass for this purpose in preference to Dynel, although Dynel will certainly work.
Dynel is an acrylic resin and its stand out characteristic is abrasion resistance, although it does have good tensile strength. It is best used as an exterior layer in an abrasion-prone location.
S fiberglass is considerably more expensive than regular (E) fiberglass but I think the improvement in tensile strength, compressive strength, and stiffness is worth the additional expense, especially since a yard of material should be fine for your repair. S 'glass also has pretty good abrasion resistance and works well for skid plates. The fibers do not swell in resin nearly as much as Dynel does, so a skid plate made of fiberglass will be much less thick than one made from Dynel cloth of similar weight. If you want a thicker plate you can just use two layers of 'glass.
I would fill in the dished-out external void using multiple layers of cloth as waterbearer suggested, orienting the fibers of the layers in different directions by cutting the patches on varying biases to the weave and warp of the fabric. Ideally try to apply each new layer while the epoxy of the preceding one is still "green" so as to maximize the chemical bond.
Each new layer should be concentrically slightly smaller, or larger than the preceding one. The number of layers will depend on the thickness of the Royalite. Some folks insist the first patch should be the biggest. I don't feel it makes any difference whether you go progressively larger or smaller with patches from a strength perspective, so I would do whatever seems easiest until the void is filled in.
If you have an interior split or hole, I would cover it with clear packing tape to avoid epoxy leak while patching the exterior, then deal with the interior after the exterior repair is done.
I prefer using aramid such as Kevlar 49 for interior patches but fiberglass will work just fine if you don't have any aramid cloth and don't want to buy a second type of fabric. If you have a through and through hole, I would cover it with an interior patch of at least one layer of cloth that overlaps the edges of your exterior repair by a couple of inches.
If you are interested in the varieties of different types of fabrics and their particular strengths, this webpage at Sweet Composites is helpful:
http://sweetcomposites.com/Fabric.html
also this:
http://www.christinedemerchant.com/carbon-kevlar-glass-comparison.html