View topic - Skid Plate Materials Testing

No guess, I checked and the answer is absolutely.

I have a 7 foot long (x 54” wide) piece of Dynel left. I didn’t feel like cutting one yard off to test mailing thickness so I folded up all 7 feet to fit inside a 9x12 envelope, stuck it in a big ziplock bag and purged the air.

Measured with a loose caliper the thickness is just a hair under ¾ inch. A yard at a time should be no problem.

Thanks Mike, really appreciate that test.

Since my existing multi-layer (probably about 6+ now) s-glass only skid plate has a few "gaps" from last summer I figure it's time to add a layer of dynel.

If I'm going to buy I might as well buy lots and as you suggest corner the Canadian market for 1 or 2 yard orders.

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"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915

.....*psssssssst*....wanna buy a yard of Dynel? .... I know a guy....





(that said...I'm likely in for a yard, keep me posted!)

The best skid plate I have installed to date.

15oz, 12ml thick biaxial glass tape up the keel line under 5oz Dynel, using a 50/50 mix of West Systems 105/206 and G/flex, with graphite powder and black pigment added to the epoxy mix.

I use a roller atop the peel ply to knock down thickness of the tape and selvage edge, and the thickness of the Dynel, which swells in resin saturation.

Not this roller, I used a drilled dowel (crappy Old Town seat hanger) but now I have a proper roller. And already have at least four more sets of skid plate installations waiting in the wings.

P5050015 by Mike McCrea, on Flickr

Epoxy cured and RO sanded with 222 on a foam disc, re-taped and painted. It took two coats of black enamel paint to fill the weave left from the peel ply, which was imprinted deeper than usual from using the compression roller.

The most time consuming part of the skid plate installation is taping and masking the area, once for the epoxy, once before sanding so I didn’t oops sand out past the skid plate edge and finally twice more for paint coats when the first coat didn’t quite fill the peel ply weave.

Seems like a lot of work to use cheap Rustoleum enamel paint at the end. I have some black Pettit EXPoxy paint to try on the next skid plates as a top coat. It may still need two coats, but it’ll be epoxy paint.

P4290006 by Mike McCrea, on Flickr

15oz tape with selvage edge plus 5oz Dynel, and everything disappeared flush and smooth using the roller on the peel ply layer. I am seriously impressed with how well even a DIY roller worked on that thick material(s) layer.

I’ve got four boats in the wings waiting for skid plates, and I’ll do exactly the same thing with them.

I'm sold, and ready to build my skid plates. It's a flatwater solo (Swift Adirondack Pack 13.6) so I'll skip the glass layer and just use a layer of Dynel (thanks, recped). I'll use G/flex 650 with some added graphite powder (I think you said less than 20% volume somewhere, Mike?). And I'll press it all thin using West System's release fabric. I'm just a bit nervous, not having worked with glass/resin in 30 years, but life's about trying, right?

Just two questions, please: First, do I really need the 32" length that pre-cut kevlar skid plates use? My canoe is only 13' 8" and I figure 20" x 2" will still go 5" past any paint I've worn thru in my 2 years without skid plates. Why not save weight after paying so much for a 26 lb canoe?

Second, I'm not thinking of painting over the epoxy once done. Will I need to sand or paint to fill in the woven pattern of the rolled-in release fabric? Will it be gurgle-noisy if I don't?

Thanks, guys.
...Terry

You don't need 32", just cover the area (plus a bit more) that has shown some wear. I would guess that the more rocker the longer you might need.

I have not used the release fabric myself, having seen the stuff I expect it leaves a rough to the touch surface that after modest use will become almost entirely smooth.

Mike might have alternate opinions as he's the one with more experience.

_________________
"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915

Terry, the can of West System graphite power I have recommends a max of 10% powder per volume of resin. I use a bit less and add it to the resin (using a plastic spoon) a small amount at a time, otherwise it is kinda flyaway when stirring it in.

You can cut the Dynel to any size you want. I’d go a couple inches outside any visible worn areas; 2” wide sounds skinny.

I use black paint over the epoxy/graphite in part for some UV protection, but mostly for the opportunity to neaten the black epoxy/graphite edges. I think (but do not know) that the graphite powder adds a bit of UV protection.

Epoxied Dynel WITHOUT using peel ply has a very rough cheese-grater consistence, with peel ply it is nearly smooth, with a very faint weave imparted from the peel ply texture. It won’t be gurgle-noisy if left unpainted. I don’t topcoat with paint until a week later in any case, so you can see how it looks unpainted and then decide.

If you do a good taping and papering job, perimeter of tape just outside where the Dynel will lie, newspaper half way up that tape, another perimeter of tape spanning the tape/newspaper edge, pull all of the tape and paper when the epoxy stops dripping down the side, lay and press the peel ply – I think you will be pleased with your results.

One helpful trick, drawing a center line down the cut piece of Dynel will help align the cloth with the keel line of the canoe as you lay the Dynel atop the epoxy base.

FWIW a skid plate install with photos (post #4 in this thread)

http://www.canoetripping.net/forums/for ... urbishment

Terry, Recped and others, I’d love to hear how your Dynel skid plates turn out, and after some trips how the material is holing up for your use.

BTW, after a short learning curve installing the first set putting Dynel skid plates on subsequent canoes got easier, cleaner, faster and better.

Thank you, Mike and recped, for your great advice. Life got in my way and I haven't done the skid plates yet, but I will indeed update you here. Phew, I'm glad you told me to apply the release fabric after you had peeled off the tape/newspaper, Mike, as I would have done it before. But doesn't pressing or rolling over the release fabric squish the expanded Dynel (good) and push surplus epoxy out onto my Kevlar canoe surface (bad)? I'm using G/flex 650.

Thanks for the link to your well-photo'ed skid plate report, Mike. I see why you suggested my 2" width be widened; your skid plate is triangular but I was thinking it should be a replacement for the retail kevlar skid plates, which are strips only 1.5" wide at the bow and maybe 3" at the 'under the seat' end. Is your base width (8"?) because this is a whitewater canoe?

Your example also surprised me because it doesn't run up the front 'bumper' of the bow to just above the water line, as I thought most Kevlar skid plates do. I agree with the easier taping, but don't you need that front bumper?

Hah, I didn't even know West System sold a graphite powder. I had been thinking of just using a bit of some 10 year old graphite powder meant as a lock lubricant. Do you think a half-teaspoon of that is better than not using any at all?

Other people do it the other way, I’m just not sure how they manage it?

If I leave the perimeter tape on, lay and roller compress the peel ply over the dripping epoxied saturated Dynel, won’t I epoxy the tape to the hull? Does that tape pull cleanly, or do I have to slice pieces of it out with a razor blade the next morning?

Maybe this is done using “green pull” (nylon) peel ply, peeled off (you hope) a few hours after the epoxy goes on? I am not fond of that just in time green pull guessing game. “HELP, somebody come hold the canoe, I need both hands!”

I love release treated peel ply; after some shop hours of cleaning, prep work and taping/papering I’m ready to lay some epoxy, cloth and peel ply and then walk away ‘’til the big reveal the next morning.

I dunno what I dunno; my way works for me and I have become seriously fast and proficient at taping and papering prep work, so efficient that I don’t mind doing it twice, once for epoxy and once for paint. Skillled enough with tape that I probably get a job with Earl Scheib.

https://www.youtube.com/watch?v=PtjdHaMeiiQ

Tape pullled off and peel ply compressed it does leave the epoxy edge a little fuzzy, but if the epoxy/graphite powder has stopped dripping before the peel ply is compressed it won’t smush out that far, even rolling down the edges.

I just wait a week, clean it, retape it and paint it with cheap black Rustoleum enamel for some UV protection and nice, neat straight lines.



Once the stems are scratched up a bit I have a target area to overlap in length/width/shape. I have installed some skid plates on minor/early scratches, kinda knowing where the stem shapes and typical use will merit protection.

I have a half dozen differently shaped skid plates on different use and stem-shape canoes. Great broad triangles on wide boats that get bow driven onto sandy beaches and shallows. Two inch wide skid plates on some sharp stemmed wetfoot lake boats.

Vee bottoms and decked hulls tend to be longer ands skinnier; I would pay the price for seamed-edge 2 or 3 inch wide Dynel tape. Someday.

Some DIY skid plates match the size and shape of Old Town (and others) kevlar felt skid plate kits. OT’s, which were neatly rounded on both ends, were 3” wide at the narrow end, 8” wide at the fat end and 36” long. Too much felt for most applications; even when I regrettably used them I often cut them down to more appropriate lengths. Lengths plural; bow and stern are sometimes wear-area different.



The taping, and especially the worse results complex-curve form fitting of a woven material along a curve is a PITA. Making a keel line slice for an inch or two down the narrow end of the Dynel helps accommodate some recurve without puckering. Rolled down (repeatedly) under peel ply even the wrinklepuckerfolds mostly disappear. But you don’t need a 3 foot long bulbous teardrop skid plate on every stem.

I have some canoes with the skid plate a few inches above the cutwater. And yeah, I have mistimed some rocky eddy and smacked a RX bow into a vertical rock. Oops, I try not to do that, even in canoes appropriate to WW.

Some of the old kevlar felt skid plate instructions read something like “Measure down five inches from the tip of the deck plate and begin the skid plate there”. On some rec canoes with classic re-curved stems that put a comical lotta fugly kev felt sticking up out of the water.

One thing with a single layer rolled-compressed Dynel and peel ply skid plate – It turns out so hull-flush and smooth that, if you mis-guessed the size, you could (years later) install a bigger/wider skid plate overtop and it would still be flush. And double Dynel layered in the center.



I have zero idea how 10 year old graphite powder lock lubricant would work with epoxy. I do like the graphite black; if that stuff is a fly-away dry powder maybe lay out a test patch of Dynel scrap, epoxy and that graphite powder and see how it turns out.

About “just a bit”, that depends on the amount of epoxy mixed in each batch. I’m in the “Can-always-pump-another” party, and mix couple or three ounces at a time on something like skid plates. I hate wasting epoxy left in the pot, and try to have some secondary use prepped and waiting, even if that if just sealing wood sawhorse feet

I put a teeny dab of black color agent pigment in the epoxy, just ‘cause I have some, and something under 10% by volume graphite powder. The graphite powder adds far more and deeper dark than the dab of pigment, and closer to 10% gets thickened less G/flex wasteful drippy down the tape and paper, and graphite slippery as hell, which can’t hurt for sliding over unseen oops.

Blahblahblahblahblah. A thoughtful material, well executed and well designed skid plate can be a thing of beauty instead of an ugly pimple plastered on the stem

Epic reply, Mike! I sure appreciate you sharing all the things you've worked out. I'll let you know how it goes... Terry

Terry, if I get to it tonight I'll post the results of the one I just finished, I've written it up but I need to edit the pics that go with it.

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"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915

OK, got that finished (sort of). I included details on all the repairs I did in order to have my boat (Mohawk XL14) ready for my summer trip. Initially I was going to post here but it was easier to put it up on my own site (Yes one day I'll create a proper main page so you can find the currently "hidden" ones).

http://www.recped.com/repairs/mohawkxl14/

_________________
"What else could I do? I had no trade so I became a peddler" - Lazarus Greenberg 1915

Excellent documenting, Mike! I agree, the key to not having epoxy overflow when pressing the release fabric is applying just enough epoxy to soak the Dynel and not much more. That plus waiting until all drips are done, but not waiting too long! Out of curiousity, how long was that for you, between applying epoxy to the Dynel and applying/pressing the release fabric?
Thanks again... Terry