C-Forum

I am considering putting a stern kevlar skid plate on the stern of my Viper 12. The stern is not cracked but is getting worn. I have already fixed a small gash caused by a rock on the stern. I am hoping to extend the life of the boat. But I am wondering if the skid plate will ruin the boat's handling? Will it increase the longevity of the boat, or will this be a waste of time and money?

Thanks in advance for any helpful advice.

Adding one won't hurt the boats handling. If you want it to last you should also reinforce the stern on the inside. This will keep the stern from getting dented which could cause the skid plate to break. It should increase the life of the boat. Hope this helps.
Bill

Check into the skid plates made by Rec Repair. See http://www.recrepair.com/skid_plates.html

I'm impressed with the ones I put on my boat. I used g/flex for the epoxy.

I'm a firm believer -- helmets on the head, and skid-plates on the stems. The stems (bow AND stern) are the first and worst parts of a royalex boat for abrasion and general hard-knox.

I've even seen skid-plates installed onto composite hulls. Looks funny, but functional.

It's doubtful the performance of the boat would be affected too noticeably. Originally, I thought skid-plates were the cause of my frequent swims, but friends have suggested other reasons. . .

Yeah, but Kevlar felt skid plates are an inferior convenience product. They developed because Kevlar has a magic name, and because Kevlar felt hangs together when wet with resin so that it can be shoved around before the resin sets.

A three to five layer S-glass cloth skid plate sits lower, slides easier, wears smoother, and has better resistance to compression blows than Kevlar felt. And if damage does occur, you can repair an S-glass skid plate much easier than one made with Kevlar felt. It takes a little more work to put on S-glass skid plates, and they don't confer the "stud" image that Kevlar does. You have to live with the image problem.

Another thing---experienced boat builder and composite guru John Sweet said that the vinyl should be skimmed off the ABS before a Kevlar felt or other skid plate is installed. That's what I did. Most people just stick the skid plate on the vinyl skin, but it may not stay on as well there.

i'd never peel the vinyl off a perfectly good boat to stick any skid plate to it.... maybe if it was already wrecked. I'd rather it pop off than do that. Just my humble opinion. WHICH is also what is being presented (opinions - as fact) in that s-glass glorification, or perhaps more appropriately termed Kevlar(tm) slam. The real reason (again IMHO) that you want something like Kevlar here, is due to it's inherit nature of staying together. The compressive nature of this material is it's very benefit, as it can be battered, and still remain mostly intact fibers (a fact). Even after all the resin is smashed to smithereens, the fibers may still be there. This action in my opinion (again IMHO) will help reduce any possible effects of an overly-stiffened piece of composite material smashing through the ABS. These are simply opinions, and are not being passed as absolute verifiable fact... and yes - I've used whole rolls of both materials, as well applying those Kevlar felt kits. My idea (IM-humble-O) is to apply a pseudo-temporary wear area, not a permanent bullet proof end. And if I have to replace one, oh well... it's done it's job. For (i believe) it's not desirable to build some inflexible cap, which will simply push through the weaker ABS. This is why Milkman's idea with using G-Flex sounds so good, as any malleability of a skid plate should be a big benefit. EZWATER's notion of the intrinsic nature of a mesh of material forming to a complex shape, is not it's only virtue. As I believe in this application, these individual Kevlar strands (again JMHO) will wear more favorably, than a matrix created by a woven-sheet of anything (including Kevlar). Which is sort of nice when applying to plastic. It's also sort of nice (and neater) to apply one thick layer of Kevlar mat, than many layers of cloth... Again these are simply my OPINION(s) - and are not being passed along as fact.

I wouldn't remove the vinyl to apply a skid plate - I would wait (to add the weight of a skid plate) until the vinyl was already worn off...

G-flex does sound appealing as does the "rec repair" material.

philcanoe--- decades of occasional Kevlar felt skid plates cracking and falling off shows what sort of compressive strength Kevlar has.

Of course, the many boats made of Kevlar felt rather than S-glass and Kevlar cloth (the latter inside where it belongs) certainly supports your point of view.

We currently have two relics in the fleet with kevlar skid plates bow and stern - one is an ancient OCA the other a Mohawk Intrepid. Three other Intrepidss of similar vintage and similarly dressed have come through the fleet and on to other homes - all paddled hard by the outdoor program at Montreat. I paddled an ME for several years that had skid plates plus the entire rectangle of felt from a kevlar skid plate kit extending from the rear plate forward along the center line. None have been babied (or particularly abused) and all are (or last I saw) intact except for small chips and divots. So, YMMV.

As for whether to remove the vinyl layer or not, what I did was simply sand it (100 grit) so that the g/flex would have something better to adhere to. I also taped the glued Rec Repair skid plates tightly to the bow and stern and left them like that for several days. I have to admit the gluing job and the bits of duct tape left on the hull weren't pretty, but I'm more of a function guy anyway.

milkman wrote:As for whether to remove the vinyl layer or not, what I did was simply sand it (100 grit) so that the g/flex would have something better to adhere to. I also taped the glued Rec Repair skid plates tightly to the bow and stern and left them like that for several days. I have to admit the gluing job and the bits of duct tape left on the hull weren't pretty, but I'm more of a function guy anyway.

As far as prep, I add to the above a barbaric and violent marring of the surface with my dremel tool.

did you flame treat?

from: http://www.westsystem.com/ss/gluing-pla ... lex-epoxy/

Effectiveness of different surface preparation techniques on the adhesion of G/flex 655 Epoxy to ABS

Method of surface prep -followed by- resulting tensile adhesion

Sand w/ 80-grit 1,854
Sand w/ 80-grit + Flame treat 1,813
Alcohol wipe + Flame treat 3,288

Thanks for posting that. Interesting that flame treating can improve even G-flex adhesion to ABS. Ordinary West 105/205 is sticking pretty dam well for me. But I have a torch and know how to use it.

I am not suggesting that Kevlar felt skid plate installers are likely to find the result unsatisfactory. I am only saying that if one wants a lighter, neater, harder, smooth wearing result, multiple layers of S-glass cloth will provide it.

And before slapping any sort of skid plate on the ends of a canoe, assess the use pattern. Because I don't run a lot of steep creeks or rocky drops, my 12 year old MR Synergy has no damage to the underside of the bow and stern. But when the vinyl wore off underneath my pedestal seat, I applied a couple of layers of S-glass and epoxy, and after three years that patch is standing up completely.

Others who know that they often run ledges and drops that hammer the ends might choose to add skid plates as soon as the vinyl starts to wear through, or sooner. Many others may never need skid plates, unless they just like the look.

philcanoe wrote:did you flame treat?

from: http://www.westsystem.com/ss/gluing-pla ... lex-epoxy/

Effectiveness of different surface preparation techniques on the adhesion of G/flex 655 Epoxy to ABS

Method of surface prep -followed by- resulting tensile adhesion

Sand w/ 80-grit 1,854
Sand w/ 80-grit + Flame treat 1,813
Alcohol wipe + Flame treat 3,288

Interesting that the sand + flame treat yielded a weaker bond than sanding alone...I guess the ROH wipe does more than superficially clean the surface.

Clean is better.. I wonder if sand & flame-treat as posted involved prior cleaning too, as I found that alcohol wipe, sand, flame treat holds best with my tests (new ABS to new ABS using GF)

? anybody up for asking West System about that?