C-Forum

Check it out here:

http://www.ipernity.com/doc/mahyongg/83 ... 1276767686

I would like to hear your thoughts. Idea so far: dry out the water soaked in, cut to shape some ABS sheet as thick as the original green stuff, lay it in the holes cut before with g-flex underneath and flush out the edges with the rest of the hull.. then cover the whole thing up with several consecutive layers of ABS putty and spray-paint over with plastic paint.

Would you suggest using fibre reinforcement instead? Anyone had a successfull repair done this way? the cracks dont go through the boat, so I am reluctant to do the usual crack-style repair with the G-flex ;D

Hope we can get a couple more years out of the beauty, so go ahead and get your fingers hot typing away.

Cheers,

Jan

Hi Jan,

Wothwhile project to get a bit of time in a Viper 11!

I might cut away all the ABS of what's delammed. I have low confidence in the delam "re-lamming", so would prefer to cut it all away and know exactly what I'm working with. The ABS sheets sounds like it could be a hassle, I think I'd go with ABS slurry as a cap after the cracks are filled.

Personally, I have not had good luck with glassing flexible areas of Royalex, so would go with the ABS slurry or sheets, byt maybe glassing is better with the new G-flex.

Good luck!

Pat.

Pat, I don't think G-flex will be better for any wide area "glassing" projects. The tricky thing is guessing what sort of forces will bear on a cloth and resin repair. This depends on both the contour of the hull, and on where and how the hull is distorted by a force.

For example, take the stern center of a boat, and ledges. The stern is not necessarily absolutely flat, usually somewhat convex. A blow to the center underside produces compression forces at the surface. But inside, there are tension forces, and nearby at the chines, the forces will be tensional outside and partly compressive inside.

Chines on an open boat take a beating. A direct hit causes compression and tension close to the blow.

If a boat is very flat-bottomed, a blow to that flatness actually causes tension stresses at the point of the blow and nearby, and tension on the inner layers.

So while we often say that S-glass and carbon are for outside, and Kevlar is for inside, there actually are cases where Kevlar or polyester may be better outside cloths, particularly along chines. And INSIDE chines, when those chines are bent by a blow to the boat's underside, Kevlar's mediocre compression strength can result in surprise damage, and S-glass or carbon may make good reinforcements.

So when I hear of the failure of a substantial outside cloth/resin patching job, I don't blame the resin (unless preparation was poor), I wonder about whether the choice of cloth was appropriate for the commonest forces affecting the area. There may even be cases where Nylon would make the best cloth.

I would be interested in what sort of failures you have had or seen with cloth/resin repairs on Royalex.

SCRAP IT!!!!!!

Darned canoeists, there is no prize for keeping a worn out piece of junk on the water. Support your boat builders and buy something. If we all keep repairing pieces of junk like that there will be no new whitewater canoes nor any manufacturers left.

SCRAP IT, CRUSH IT, TRASH IT, IT IS A PIECE OF JUNK.

I tend to avoid using the slurry where the foam is exposed - I think the solvent will just eat away what it contacts. I've used PC-7 (2 part epoxy with great success (that stuff lasts for years - 10+) . I've also injected urethane glue (i.e. Gorilla Glue) into delaminated areas then cemented on a sheet of ABS.

I repaired a similar wear patch on a Viper 12 (but no foam exposed) by merely cementing on a sheet of ABS. Like yours, it wasn't on the chine so a flat piece worked fine. It wasn't flush, though I may have used a little cement to fillet the edge. I guess the stress riser wasn't significant - the patch was solid when I swapped the boat for a case of beer 2+ years later. However, the chines were shot and I'd cracked the bow in a piton by then

Keep it simple and get it patched in an hour or two - use the remaining time to paddle.


Mr. Deadlegs does make a point, but I don't think that one is ready for the scrap heap yet.

Scott swapped the Viper 12 to billcanoes for beer. I acquired it for some other gear. I cut the whole center 28" of the boat away. It was trashed. I was going to join the two ends together to make a Viper 10.1, but the boat eventually ended up in little tiny pieces in the dump. Basically, Scott stole a case of beer from Bill Reap. That ABS sheet that Scott cemented on was still very much intact when I cut up the boat.

If we all keep repairing pieces of junk like that there will be no new whitewater canoes nor any manufacturers left.

On the other hand, we want them to know that we're not happy dumping fresh money into new boats that aren't durable. When they make a boat that can withstand a beating better than the Royalex we've got, I'll buy new. Until then, I'm not willing or able to spend a few grand every few seasons on boats that get banged and go soft!

Pat.

p.s., EZ, the cloth & resins repairs I've done & seen either crack &/or lift or cause cracking around them, mostly just eventual lifting because they don't flex with the hull. Perhaps no big deal since no repair lasts forever. And maybe they weren't done done perfectly by experts - but that's the case with most repairs!

I suspect that one reason cloth/resin patches don't do well on Royalex is that they are difficult to plan so that they patch will match the original flex/extend behavior of the Royalex. Instead, the patch sits on the surface like a limpet, and when the hull is bent hard, the patch cracks or pops off.

When an "ideal" patch is done on a composite hull, like a slalom boat or a Millbrook, the hull is tapered, the cloth is chosen to match the original, and the # of layers of cloth result in a patch that is essentially part of the hull. It bends like the original hull, so it stays on.

My main Royalex patching project is a wear patch on the bottom of my Synergy, right under the solo spot in the triple saddle. The vinyl had worn off. I put on a two layer, concentric, S-glass patch. It has worn like iron and has not cracked or popped loose. But while this is a high stress area, the pedestal does limit the extent of bending. It would be more interesting to do a chine repair. Unfortunately I was never very hard on boats, and at my age, my boats are not stressed much at all.

Hi Guys,

thanks for all your input - I guess covering it with cloth is not an option, although I have a polyester fleece that has interesting properties. The darn thing with the bottom flats is probably that it gets compressed OR pulled at depending on where you hit a (rock).
I guess what you really want is something that flexes with the hull, as the original hull material does. So i am probably going for just the ABS "inlay" method, to mimic what was there.

I guess I am going to remove that ABS which is delaminated. Might keep whatever is still attached to foam. Set up a couple of glueing experiments yesterday evening, so I'll see how that works out (NEW ABS sheet to foam, ABS to ABS, ABS sheet to OLD ABS, ABS to ABS non flame-treated). Will be fun to destroy these I hope..

Regarding scrapping.. yeah we thought about a Viper 10 as well.. but that did seem too early. I'd rather repair anything than throwing it out, if it can be done and reliably. Which is the case with glueing plastic. Rather than using any more dinosaur juice.. hey maybe we can just toss it in the Gulf and it repairs itself?
Then, its not even my boat. I am just supporting a paddling friend. My guess is for him its either the repair or no Viper, so..

Besides, if Esquif wants to they can pay me to design reliable anchors and a new logo, then I would be able to afford a new boat. Heck, they could pay me with boats if they wanted. But they probably don't, otherwise they would have these already, innit?


;D

Cheers,

Jan

ncdavid wrote:... Basically, Scott stole a case of beer from Bill Reap. ...

Hye now! In the interest of full disclosure, I talked him *down* to only a case of beer! However, I do admit I got the better end of the deal... I certainly got my money's worth out of that boat - lots of river miles and smiles in that Viper...

One of the other repairs I tried on that boat was to put some glass on the chine. I already had some West Systems resin and the local West Marine had some seam tape that kinda looked like it might work (I didn't know better then and, for that matter still don't). I put 2 layers per side, maybe 4' along each chine. That was on there about a year - it seemed to work OK as it never popped off. The only problem was the "fiberglass itchies". That got really annoying as I'd roll the boat up on my thighs everytime I'd dump it or pick it up to carry it. That might be the single biggest reason I finally gave it up. That and I was thirsty and Bill had a case of beer

I used a Rec Repair skid plate to fix a soft spot in the bow of my Phantom and it worked great. Glued it on with g/flex. Seems like a bomber repair.

I wouldn't try a sheet of the Rec Repair stuff (I think it's available in sheets) on a large patch on the bottom of a boat though. The Rec Repair material doesn't have enough rigidity and stiffness. It can easily be shaped by a heat gun though and hold its shape, so I'd be tempted to try it on a soft chine.

yarnellboat wrote:

If we all keep repairing pieces of junk like that there will be no new whitewater canoes nor any manufacturers left.

On the other hand, we want them to know that we're not happy dumping fresh money into new boats that aren't durable. When they make a boat that can withstand a beating better than the Royalex we've got, I'll buy new. Until then, I'm not willing or able to spend a few grand every few seasons on boats that get banged and go soft!

Pat.

p.s., EZ, the cloth & resins repairs I've done & seen either crack &/or lift or cause cracking around them, mostly just eventual lifting because they don't flex with the hull. Perhaps no big deal since no repair lasts forever. And maybe they weren't done done perfectly by experts - but that's the case with most repairs!

plastic .... my skeeter is still holding strong after being molded in what 96 or 97

and my luck with Royalex i cant get anything to glue to it ... got an old ocoee that the knee cups need regluing .... and the vinyl to glue the Velcro to dont help matters

Hmm, sounds great with all your successfull repairs and patches. I just destroyed three test pieces I made - interesting to see, Gflex does glue to ABS very good for pulling strength, obviously (as mentioned before) it can be sheared off quite easily, so I decided to try a "mechanical" linkage for the repair as in the following drawing:

http://www.ipernity.com/doc/mahyongg/8336378

What do you think of that.. should work in my opinion.

Cheers,

Jan

I've wondered about using holes and resin like that myself. It would seem to make a stronger structural bond than just gluing sheets together. But I'm no engineer.

ABS cement. Its a solvent (acetone? MEK?) W/ABS dissolved in it to a consistency of elmers glue. It essentially welds ABS together. Bomber. Simple. Cheap.