C-Forum

Hi,

I'm trying to find information on how to fix damaged skid plates. The outfitter who installed them did a very poor job and the epoxy remained wet for a long time and ran throughout the hull of the boat leaving nasty streaks of epoxy. Also, the skids plates are torn in some spots due to soft plates. The boat is a Mad River Canoe and made of ABS. Since the outfitter is now out of business, I'm on my own for the repairs.

Does anyone know the best way to fix the plates and clean the hull of the boat?

Thanks,

matt

I'd like to add to this - I recall a conversation last fall at Moose fest about skid plates and epoxy. I had just cracked the skid plates I had installed on my Detonator (Kevlar felt with West System epoxy) and I heard it suggested that West system was too brittle to make good skid plates and that some other resins were better. Does anyone have any feedback on this? I'd like to get this repaired, but don't want to make the same mistake again.

Cheers

Matt

PS. Matty T - sounds like the outfitter used the wrong resin/hardener mix. I'd rip them off, clean the hull as best you can and start afresh.

I put two strips of woven Kevlar cloth underneath the Kevlar felt. This helps prevent the felt from cracking. If the felt does crack the Kevlar cloth will help keep the felt from falling apart.

I would sure would like to find out the name of the more flexible epoxy and where to buy it. It would be just the ticket for patching holes in ABS canoes.

Back when I was a boatbuilder, a sales rep gave me a sample of cured flexible epoxy. The sample was a rod 1/2" in diameter and 12" long. It was flexible enough to tie in a knot. I believe the rod was made with two part epoxy, mixed and used like any other epoxy.

This was eight years ago, but the company may still offer the product. Try MAS Epoxies, at http://www.masepoxies.com, or 1-800-MAS-EPOXY.

I never used their flexible product, but the MAS products that I have used all work as advertised. I remember their tech support to be quite good, as well.

I make skid plates totally out of cloth and West epoxy. I prefer S-glass, but will use e-glass if that's all I have.

Many don't realize that Kevlar felt does not make a particularly good skid plate. It has two things in its favor, the Kevlar name, and the fact that Kevlar felt holds together well when sopped into a batch of urethane resin. West epoxy probably is too stiff to use with Kevlar felt.

But for anyone with patience, the properties of S-glass make it excellent for skid plates. Strong in compression, very good modulus, wears smooth (does not fuzz), and drags easily over surfaces. Thinner skid plate, does not affect hydrodynamics.

I recommend scraping off the vinyl before putting on a cloth patch. I think the epoxy adheres better to the underlying ABS. The cloth layers should be cut on the bias so they drape well over bow and stern contours. The first cloth layer should be the largest, and so on down to the smallest. Using roughly 6 oz cloth, I am likely to use four or five layers.

If you want to mix in some Kevlar layers with the S-glass, that's OK, but Kevlar fuzzes and is not particularly strong in compression. Most blows to the bow and stern will put compressive loadings on skid plates, so Kevlar's excellent strength in tension is of little use. If you want to use Kevlar, I would use it for the first, largest layer, and use S-glass for succeeding layers. Then while the epoxy is still wet, tape on some food wrap to press the layers together and squeeze out excess resin.

I've never had a problem with the Kevlar felt; I mean you're whacking into things at this amazingly high speed of what, 9-11 mph? The main problem that I found with most skid plates is that there's way too much resin put into the mix. You just want to barely impregnate the felt, and that's it. You should not be looking at a skid plate that in any way resembles resin over cloth, but rather a skid plate that looks like Kevlar felt that has hardened. I hope that makes sense. When you rub your hand over a skid plate it should feel rough and textured; barely coated with resin, rather than smooth and glassy and stiff. If it is smooth and glassy and stiff you then basically have a piece of resin which when smashing into the rocks will just crack like a piece of resin. ANY type of cloth or felt that's overloaded with resin is just going to be cracking like straight resin, basically. As to NZMatt, I've put pads on a lot of open canoes with West system and other epoxies and I usually just use the least expensive epoxy available. Again, I don't have any problem with any type of epoxy because I barely have any epoxy in the felt pad.

If you don't care about looks, the easiest way to fix the skid plates is to tear off all the portions that are loose or soft and then patch them with a Kevlar paste.. Again, it's MAINLY Kevlar cloth cut into little teeny tiny really really small, as small as possible, pieces (or you can tear up some Kevlar felt if you have some left over) mixed with a TINY bit of resin and some Cabosil (sp?) if you want to make it even less runny. Sand and clean your existing skid plate, and then just Goober the paste into the holes and then smooth it and sit and watch it as it hardens, firming up and smoothing out any new forming discrepancies..
Hope this helps
Ric Taylor

SOunds like I oversaturated the felt then. I had thought it was meant to be heavily soaked in the resin - from some other giudelines and descriptions I'd heard or read. I'll probably peel em off and start again.

Cheers

JAQ, how much do the skid plates cost, ie the epoxy/cloth/felt etc..?

thanks, Mike.