Skid plate suggestions

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Just as I was getting ready to wash the mud off my Old Town Pack 12, I noticed I had a pretty considerable gouge near the stern. Given there was also a little yellow rub spot starting to form near the bow, I think it's high time for skid plates.
These would be virgin skid plates, and even though I've read through as many skid plate discussions as I could find, it seems that the only consensus is to stay away from Kevlar.
I'm leaning toward Dynel sleeves but I'm still a little clueless as to what I should buy for epoxy/resin/peel ply and what quantities of each I should be getting.
Any advise would be greatly appreciated.
 

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I think from the pic I would go with Dynel cloth and not sleeve, I've used both. It looks like the cloth would cover better. I use West System 105/206 (I think that is right) for resin and on skid plates I mix in G-Flex which makes the skid plate rock solid. I'm sure other will chime in.

dougd
 
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I don't know if we are looking at the bow or the stern. I can tell you that anywhere the green has worn off is exposed ABS that is subject to UV degradation and needs to be covered with something opaque, paint if nothing else. So if there is any area of hull that is missing green vinyl that is not covered with your abrasion plate, paint it with any type of paint that most closely matches the color of the hull and accept the fact that you will never get an exact color match. An alternative is to mark off a 3" waterline and just paint everything below it. If you go that route I would suggest Pettit Easy Poxy paint.

As for the abrasion plate, yes I agree that Kevlar felt sucks. Its only virtue is that it is easy for those unfamiliar with laminating with fabric and epoxy to use since it does not fray at the edges and maintains its shape. But it stands way proud of the adjacent hull surface, is difficult to nicely feather into the surrounding hull because of the tendency of aramid to fuzz up when sanded, it soaks up a lot of resin, and for its final weight a Kevlar felt skid plate is actually pretty weak. The Kevlar fibers are individually strong but like all felt materials it consists of short, compressed fibers. When Kevlar felt skid plates receive a good hit it is very common for a sizable chunk of irregularly shaped material to break off.

You have a Royalex canoe. Far and away the best epoxy to use is straight West System G Flex. It will give a better bond than conventional epoxies like West 105/205-206 of a mix of that and G Flex. And for the repair you have at hand the smallest quantity of G Flex you can buy will be enough to do the repair and apply and abrasion plate. Straight G Flex epoxy is more viscous than conventional epoxy and it takes a bit longer to wet out fabric but it does just fine with all plain weave fabrics I have used up to 6 ounce/square yard weight including Kevlar, fiberglass, Dynel, and carbon fiber. Warmer ambient temperatures or gently warming the mixed epoxy prior to application will reduce viscosity if need be.

You have an area of exposed foam core in the photograph that should be filled in prior to application of an abrasion plate. I would use G Flex epoxy moderately thickened with silica powder for this allowing it to settle into the "pores" of the foam core and repeating the application until the area is slightly overfilled. Then after the epoxy is cured you can sand it fair and flush trying to maintain the curvature of the hull contour.

Either 5 ounce/square yard Dynel fabric or 6 ounce/square yard S fiberglass are excellent for abrasion plates. Or you could lay down a layer of S 'glass and cover it with a Dynel abrasion plate. Dynel fabric has a bit less tendency to fray at the edges. Fraying will also be reduced by cutting out the fabric for your abrasion plate "on the bias". In other words, situate the fabric so that the fibers of the weave and weft cross the long axis of the canoe at 45 degree angles. I like to mix graphite powder into the epoxy used to apply abrasion plates but you can also just paint it after the epoxy has cured and been washed.

Here is an old thread that contains a lot of "tricks" for applying abrasion plates: https://www.canoetripping.net/forum...ussions/diy/17299-​skid-plates-an-evolution
 
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To give you an idea, here is a skid plate of 5 ounce/square yard Dynel I applied to a Royalex canoe (Blue Hole Sunburst II) that I use as a river tripping boat. I mixed graphite powder into the G Flex epoxy used to wet out and fill the cloth. It has taken a few scrapes and hits but is holding up quite well.

skid plate.jpg
 
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To give you an idea, here is a skid plate of 5 ounce/square yard Dynel I applied to a Royalex canoe (Blue Hole Sunburst II) that I use as a river tripping boat. I mixed graphite powder into the G Flex epoxy used to wet out and fill the cloth. It has taken a few scrapes and hits but is holding up quite well.


That is exactly what I am looking to achieve and the gouge is located maybe 8"-10" behind the seat so it should easily be covered by an abrasion plate.

So do you think I’d be alright if I got two yards of s-glass (http://www.uscomposites.com/cloth.html), two yards of dynel (https://sweetcomposites.com/Polyester.html) and two four-ounce bottles of g/flex?
 
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I think from the pic I would go with Dynel cloth and not sleeve, I've used both. It looks like the cloth would cover better. I use West System 105/206 (I think that is right) for resin and on skid plates I mix in G-Flex which makes the skid plate rock solid. I'm sure other will chime in.

dougd

Thanks dougd, I think the cloth is probably the way to go over the sleeve
 
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That is exactly what I am looking to achieve and the gouge is located maybe 8"-10" behind the seat so it should easily be covered by an abrasion plate.

So do you think I’d be alright if I got two yards of s-glass (http://www.uscomposites.com/cloth.html), two yards of dynel (https://sweetcomposites.com/Polyester.html) and two four-ounce bottles of g/flex?

I yard of either will be enough and I (pair) of G/flex bottles. Also get a yard of release fabric which will help you force the wetting out of the fabric and give you a nice even finish. You need to use enough G/flex to fully wet out the fabric (especially the Dynel) but you don't need to drown it like is done with Kevlar felt, all that does is make a ton of ugly drips to clean up.
 
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Also get a yard of release fabric which will help you force the wetting out of the fabric and give you a nice even finish. You need to use enough G/flex to fully wet out the fabric (especially the Dynel) but you don't need to drown it like is done with Kevlar felt, all that does is make a ton of ugly drips to clean up.

And the good news is that if you use a release fabric it will soak up much excess resin and greatly help with runs.

I know g/flex is popular with a lot of members here, and I don't doubt that it's good stuff, but there are many of us who have never used g/flex and get along fine. By all means go with g/flex if you have access and want to use it but don't feel like it's a necessity if it's a hassle to procure. Many of us use RAKA for everything.

Alan
 
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Thanks for the advise everyone.

For simplicity’s sake, I think I might just order everything from Jamestown Distributors unless anyone has any other suggestions.

In my cart I have one yard of Dynel fabric (5oz, 55” width) $20.24, WEST System G/flex 650 liquid epoxy resin and hardener 8oz kit $26.26 and WEST System vacuum bagging release fabric (60in x 9in) $11.10 plus $9.99 shipping for a grand total of $67.59.

Given this is the first time I’ve attempted anything like this, I don’t know if this is a good deal or not, but it looks like all these materials have good reviews.

Should I also add some sort of a pigment to the epoxy or can that be painted?
 
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Thanks for the advise everyone.

For simplicity’s sake, I think I might just order everything from Jamestown Distributors unless anyone has any other suggestions.

In my cart I have one yard of Dynel fabric (5oz, 55” width) $20.24, WEST System G/flex 650 liquid epoxy resin and hardener 8oz kit $26.26 and WEST System vacuum bagging release fabric (60in x 9in) $11.10 plus $9.99 shipping for a grand total of $67.59.

Given this is the first time I’ve attempted anything like this, I don’t know if this is a good deal or not, but it looks like all these materials have good reviews.

Should I also add some sort of a pigment to the epoxy or can that be painted?

A nice feature of G Flex is that it can it is mixed in equal volumes of resin and hardener and the mix can be off one way or the other by 20% and it will still cure. This allows very small batches of epoxy to be mixed by eye. Compare that with West System's 105 resin and 205 or 206 hardener where the mix ratio is much more critical and to consistently get it right requires most people to also purchase mini-pumps for the resin and hardener. But the mini-pumps have a fixed volume per stroke and many times the volume of mixed epoxy resulting from one pump each is more than you need resulting in wastage. Being able to mix small batches will be especially helpful when filling in that exposed foam core. And G Flex does produce a stronger bond to ABS and PVC (vinyl) than their 105/205-206 conventional epoxy, which has been some of the best in the industry in my hands. West System does a lot of testing of their products to assess bond strength to various materials and they are happy to share that information with you. A lot of it is published on their website but might not be easy to find. Skid plates tend to get subjected to considerable sheer stress.

If I am applying skid plates or patches to a composite boat I would use conventional epoxy but for Royalex G Flex is the way to go and can be purchased in smaller volumes, but still enough to do the job.

The above prices are pretty good. I have purchased stuff from Jamestown many times and never had a bad experience. I have purchased supplies from Sweet Composites more often but I have never found treated mold release fabric on their site. The do sell nylon fabric that works as peel-ply but you need to remove it when the epoxy cure is still green. If you try to pull it off too soon you will lift up your underlying cloth. Too late and it can be pretty tough to remove, although I have always gotten it off. The West vacuum bagging release fabric is much easier to use.

Conversely I don't know if I have ever found S fiberglass on Jamestown's site. I have used a lot of the style 6533-60 S fiberglass (6 oz./sq. yd. plain weave) that Sweet sells. One 36 x 60" piece costs $23 and would be plenty. Sweet also sells 5 oz/sq.yd. plain weave Dynel in 54" width for $14.10 per yard. The 650-K G Flex kit does contain some moderately useful extras including a couple of mixing cups, plastic stir stick/applicator spatulas, a small container of colloidal silica powder, a couple of "dental" syringes with drawn out tips, a couple of pairs of disposable gloves and a few alcohol pads. But you can also just buy the 4 ounces of resin and 4 ounces of hardener without the do-dads. Sweet sells the 650-K kit for $30 and the plain 4 oz hardener/4 oz resin (650-8) for $20. I suspect that 4 ounces of hardener and 4 ounces of resin will be sufficient but if you have doubts you could get one 650-K kit and one 650-8.

I like to add graphite powder to the epoxy used to apply skid plates but if you don't like the contrasting black color you could just paint the final result. And you may not want or need to apply a skid plate large enough to cover all the exposed ABS. So you could just plan to paint the skid plate along with all of the exposed ABS up to a 3 inch water line. You can add pigment to the epoxy but you won't get a color match. To my eyes a contrasting color often looks "more intentional" and better than approximately the same color that does not match. Wash all of your cured epoxy well before painting.
 
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For simplicity’s sake, I think I might just order everything from Jamestown Distributors unless anyone has any other suggestions.

In my cart I have one yard of Dynel fabric (5oz, 55” width) $20.24, WEST System G/flex 650 liquid epoxy resin and hardener 8oz kit $26.26 and WEST System vacuum bagging release fabric (60in x 9in) $11.10 plus $9.99 shipping for a grand total of $67.59.


Should I also add some sort of a pigment to the epoxy or can that be painted?

It is easier and shipping cost less expensive to order everything needed from the same vendor.

You might add a tube of black color agent pigment if you want the Dynel fabric colored through and through and not just painted on top. Epoxied Dynel comes out sort of milky white, and any paint layer will scrape off down to the Dynel. I add some graphite powder to the epoxy/pigment mix for toughened/slippery skid plates, but the smallest can of graphite powder is many times more than you will need.

I have never used straight G/flex on a skid plate, but instead somewhat strategic* coats of West 105/206, G/flex and pigment, with top coat(s) including both pigment and graphite powder. Some experiments with Dynel have shown that a thinner epoxy mix better penetrates/impregnates the Dynel. That mix has proven to adhere well to Royalex, but the 105/206 would be an additional expense.

On composite boats the first epoxy coat is just 105/206 and pigment, with G/flex and graphite powder added to the top coats.

*I use a mix of 105/206 and G/flex mostly because I’m cheap and have both on hand. 1[SUP]st[/SUP] epoxy coat on the hull just the epoxy mix and pigment, don’t really need the graphite powder underneath the Dynel, just on top. Then lay the Dynel, top coat the same mix of 105/206, G/flex, pigment and graphite powder. Often a second top coat of the same with more G/flex in the ratio, to fill any remaining weave exposure with the same. It is hard to fully fill the Dynel weave right at the curviest part of the stem.

P5050017 by Mike McCrea, on Flickr

To the actual repair – there appears to be a deep slice and gouge through the vinyl skin and ABS layer, all the way to the foam core. You’ll need to fill and fair that first with G/flex. DO NOT get acetone of any solvent near that exposed foam core slice, it will disolve the foam and ABS.

Add the hardware store stuff; painters tape to mask the area, disposable brush and – important – a cheap wallpaper roller to compress the Dynel & epoxy mix under the release treated peel ply. Dynel swells “like an old sweatshirt” when epoxy impregnated; you can push down atop the peel ply with a gloved hand, but a roller works better.
 
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​ Dynel fibers do tend to be "thirstier" than fiberglass fibers and soak up more resin. At summer ambient temperatures G Flex, while more viscous than conventional epoxy, will wet out 5 ounce Dynel fabric just fine. I have applied more than 2 dozen abrasion plates to Royalex canoes using G Flex and Dynel cloth. But you do have to pay a bit more attention to make sure that none of the fabric is "resin starved". When applying a Dynel patch or plate to a Royalex canoe I will often gently warm the hull with a hair drier or heat gun on low, then apply a layer of the G Flex before laying the fabric on. When I think I have the fabric completely wetted out, I usually wait 15 minutes or so before applying any peel ply (when I use peel ply) and go back and apply a bit more epoxy to any areas that look as if they are incompletely saturated. Then lay on the peel ply. I have not used a roller. I have had good luck using a flexible plastic squeege. If you have an area of wear in the center of the hull that is not close to the stem and you want to avoid a long abrasion plate you could also consider applying a keel strip and smaller end skid plates. I did that on this old Mad River Royalex ME which had pretty severe keel wear in the center of the hull resulting from its extreme rocker and shallow V hull configuration. The abrasion plates and keel strip are 5 ounce/square yard plain weave Dynel. They were applied with straight G Flex epoxy with graphite powder mixed in.
 
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When applying a Dynel patch or plate to a Royalex canoe I will often gently warm the hull with a hair drier or heat gun on low, then apply a layer of the G Flex before laying the fabric on.

I “warm” any epoxies if they are cool to start with, usually by sticking them atop a bathroom vanity (one of the few rooms we heat in winter) overnight. Any epoxy, especially G/flex, is more viscous when cool.

I had not thought about warming the hull, makes sense. I could do that with a radiant oil heater set below the hull, something I do off-season in the (largely unheated) shop to keep the hull warm while paint or epoxy cures.

PB050012 by Mike McCrea, on Flickr

If you have an area of wear in the center of the hull that is not close to the stem and you want to avoid a long abrasion plate you could also consider applying a keel strip and smaller end skid plates

This (black) is a full length 1 ¾”wide Dynel sleeve keel strip on a vee bottom that was badly worn

P6050019 by Mike McCrea, on Flickr

Dynel sleeve, being two layers folded together () and epoxied at once, with no opportunity to top coat the “bottom” layer, is more difficult to thoroughly wet out.

This is Dynel sleeve wetted out with pigmented epoxy after compression under peel ply. The wee bit of white showing is from cutting the test piece in half.

PC060024 by Mike McCrea, on Flickr

This, on the right, is pigmented epoxy on Dynel sleeve without peel ply compression. The lack of complete saturation is apparent by the larger amount of un-pigmented white showing in the center.

PC200028 by Mike McCrea, on Flickr

I’ve done a fair number of Dynel and graphite powder skid plates, sometimes going four-at-once production run. Left to right, all with graphite powder and black pigment: Dynel fabric, no Dynel just G/flex and pigment over a poorly installed kevlar felt skid plate, Dynel sleeve, Dynel fabric.

PB180013 by Mike McCrea, on Flickr


I really like using the roller; I think I can get more downward compression and there is less chance I’ll wrinkle the peel ply or Dynel. I hard roller compress almost everything under peel ply now.

The roller pressure down a marvelous job of knocking down the raised selvage edge of E-glass tapes. I did that first with a large nail through a drilled dowel and liked the result so much I bought a small hard roller just for that purpose. Even something like this will do.

https://www.homedepot.com/p/Piranha-...2314/203809609
 
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I may be repairing an old Mohawk XL 13 soon, and applying abrasion plates and a center keep strip. I will give the roller a try. Unfortunately, all of the cheap rollers I have tried last about a day before the plastic roller drum falls off.
 
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I will give the roller a try. Unfortunately, all of the cheap rollers I have tried last about a day before the plastic roller drum falls off.

Pete, after I saw how well the drilled dowel worked I bought one of these

https://www.amazon.com/Deadening-App...4478726&sr=8-9

I’ve used it on a dozen skid plates and keel strips, bearing down on it with considerable pressure. Still good as new.

P5240019 by Mike McCrea, on Flickr


Bear down Joel, that's Dynel sleeve under peel ply.
 
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Mike, Pete, I really wish I could buy you guys a beer, was honestly not expecting this much expert advise for this project, so the pressure is on. My order with Jamestown is supposed to arrive by Monday so I'll have some photo updates for everyone next week. I did add some black pigment to the order but I'm assuming the graphite you guys are talking about is the same stuff that's used to lubricate locks and what-have-you, so that should be at the hardware store.

After looking at Mike's photo of the full-length keel strip, that's probably the route I should have gone, but that can always be another project for another day I suppose.

Thanks again guys
 
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was honestly not expecting this much expert advise for this project,
I'm assuming the graphite you guys are talking about is the same stuff that's used to lubricate locks and what-have-you, so that should be at the hardware store.

I’m not surprised you received actual been there/done that advice, that’s a large part of what this board is about. The surprising part is that five different boat repairers all agreed that Dynel, (at least some) G/flex, pigment/graphite powder and peel ply is the way to go when installing skid plates.

It’s is hard to get five canoeists to agree that water is wet, much less agree on a choice of materials. There are a lot of possible choices for skid plates; kevlar felt (ugh), Keel Easy kits (meh), multiple layers of fiberglass cloth with some laid on the bias (not as abrasion resistant as Dynel/more work), and worse (duct tape, just epoxy, just neverever install skid plates).

About the graphite powder, someone on this board tried using (old) automotive graphite powder lubricant. I don’t know if there is a difference between that stuff and West System 423, but the results were less than satisfactory.

West 423 recommends adding a max of 10% by volume to the epoxy mix.

https://www.westsystem.com/423-graphite-powder-2/

423 is an ultra-fine marine grade graphite powder and the composition may be different from lubricating graphite powders.

https://www.westsystem.com/wp-conten...e-Powder-1.pdf

Couple more notes. A full length keel strip works better on a hull with a vee bottom, where the wear accumulates along the apex of that vee.

If you wanted additional impact resistance you could install a layer of material, cut/laid on the bias, under the Dynel. E-glass or S-glass works fine. Probably not necessary on a Pack, maybe worthwhile on a WW canoe that might see more hard impact at the stems.

Since my skid plates are pigmented black - a tiny pencil eraser-sized dab of pigment will tint the resin mix sufficiently to thoroughly color the fabric – after the epoxy has fully cured I top coat them with black paint. Hardware store black enamel works fine. I re-tape the skid plates and brush on a coat of paint; that provides some UV protection to the epoxy and fabric, but mostly allows me to “sharpen” up the lines so everything looks neat.

It’s early, but I’ll take that beer now.
 
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Mike, Pete, I really wish I could buy you guys a beer, was honestly not expecting this much expert advise for this project, so the pressure is on. My order with Jamestown is supposed to arrive by Monday so I'll have some photo updates for everyone next week. I did add some black pigment to the order but I'm assuming the graphite you guys are talking about is the same stuff that's used to lubricate locks and what-have-you, so that should be at the hardware store.

After looking at Mike's photo of the full-length keel strip, that's probably the route I should have gone, but that can always be another project for another day I suppose.

Thanks again guys

Actually it's far removed from the pure graphite powder that boat builders use. graphite lubricants contain things like acetone (60-85%), binders like paraffin or carnauba wax, surfactants, and propellants (if aerosol), none of which is good for your purpose because they can cause problems with adhesion and may actually damage the hull.
 
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QUOTE=scoutergriz;n125986] Actually it's far removed from the pure graphite powder that boat builders use. graphite lubricants contain things like acetone (60-85%), binders like paraffin or carnauba wax, surfactants, and propellants (if aerosol), none of which is good for your purpose because they can cause problems with adhesion and may actually damage the hull.[/QUOTE]

Thanks, good to know and kind of what I suspected, but I was too lazy to do the research. And didn’t need to.

Some years ago I bought a small can of West 423 graphite powder, 6oz or so, and thought “Ah, a lifetime supply”.

I’m now working my way through a 12oz can, but that’s after a lot of skid plates. Not sure West System still sells the smaller cans.
 
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Mike, Pete, I really wish I could buy you guys a beer, was honestly not expecting this much expert advise for this project, so the pressure is on. My order with Jamestown is supposed to arrive by Monday so I'll have some photo updates for everyone next week. I did add some black pigment to the order but I'm assuming the graphite you guys are talking about is the same stuff that's used to lubricate locks and what-have-you, so that should be at the hardware store.

After looking at Mike's photo of the full-length keel strip, that's probably the route I should have gone, but that can always be another project for another day I suppose.

Thanks again guys

Hulls with shallow or deep V contours are prone to wear down the keel line. So are highly rockered canoes. Whitewater canoes will often wear through at the center before they do at the stems. That is where the hull draws the most water in a highly rockered design, and is also where the paddler's weight is concentrated. That creates a lot of abrasion as the canoe goes over rocky ledges and shelves.
 
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