C-Forum

One of my Royalex canoes has had its bow punched in several times. After the first hit and pop back out, it hasn't taken much to punch it in again. I'm looking to reinforce the bow so it can take a reasonable hit without punching back in. I was thinking an S-glass with G/flex resin patch on the inside of the bow as a possible solution, but am afraid that would just crack with the right hit.

Reading the repair advice here, I'm now thinking the ultimate solution might be to soak a sheet of ABS in acetone for 15 minutes and then apply it on the inside of the bow. I'm wondering if I would need to remove the vinyl later (which is perfectly fine) or whether I could the acetone-soaked ABS would bond with the vinyl (isn't acetone or MEK one of the ingredients of vinylbond?)

On the outside of the bow, I'm thinking of applying some sort of skid plate, perhaps the one offered by Rec Repair.

Thoughts?

I recently tried the "soak a sheet of ABS in acetone and slap it on the boat" method. I think I'll try it again, but I'll get a better "tray" to soak in - I used an automotive drip pan and it was too shallow. Other things to note - the acetone evaporates quickly and the resulting sheet of ABS can be tricky to handle. Get good gloves, the PVC gloves I got at Lowe's seem to do OK. Be careful with the excess acetone - there will be a lot of ABS in solution. Mine was black and a spill on concrete looks a lot like an oil spill but is harder to clean up...

I found the edges wanted to curl up (I was patching the outside) so I ran some clear packing tape across the boat. This was a big patch, maybe 2' long, 15" wide at one end and 4 at the narrow end. I found the ABS bubbling up (under the tape and not) as the acetone tried to boil off so I poked holes with the tip of a nail wherever I saw that. When the plastic had set up, I pulled the tape off. The finished product isn't pretty but it's sound. We ran a low/medium class II trip with some inexperienced folks a month ago and it held up fine. I'll go inspect it this evening if I get a chance. I might have taken pictures of the process, can't remember...

I think patching the inside might avoid some of my issues (i.e. appearance, worrying about the curling edges), but I would be careful about excess acetone puddling between patch and hull. Don't worry about the bond - it will stick.

Mark,

I've got an ABS sheet supporting the inside of my canoe, not my bow, but in front of the saddle, I glued it on with the 3M 2-part adhesive, which has has held perfectly for a few years now. I didn't want to mess with locking in acetone.

I also have a internal patch supporting a bashed-in bow. There I went with 2 layers of fiberglass, because it's so much easier to fit the glass into the narrow curves inside the bow. I didn't think a sheet of ABS would easily conform to that bend. Maybe that depends how easy it is to access, my was under an extra large deck plate, and I could barely reach up there.

I've just done that recently and haven't used the boat much, so not sure whether it will just crack off. Hopefully not, because it's not like that part of the boat flexes a lot, should be OK, especially with a bang plate on the outside too.

If you do go with fitting an ABS sheet in there, you might want to consider shaping it with a heat gun and glueing it in, instead of melting it with acetone.

Pat.

I think the challenge will be to get the ABS to fit to the curves - even soaked with acetone you may find it challenging to get it to fit well. Heat is another option, but I'm not comfortable risking turning our oven into a toxic waste site...

Another option would be to cut thin strips (1-2" wide) and cement them in, building up a repair.

The more I type about this, the more I think I'd try glass + G-Flex...

this summer i repaired my royalex ovation that had a stern dented in about the size of a grapefruit. i ended up getting kevlar skid plates and using g flex to repair/cover the damage. so far they are working great. the ones that i got are about 8 inches wide at the widest part. they've seen some abuse since their installation and they are really tough!

Actually, I like the idea of the ABS strips. The bend in the strips would add the extra strength because they would be flexing outward. Add a protective layer on the outside of the boat and it could be pretty bomber. It should also be easier to heat and bend a strip to fit than a square of ABS. Or, if I go with a soak in acetone, it will be a small operation than dealing with a bigger patch. I think I'll play with that and if I can't get the strips to hold their bend, fall back on g/flex and fiberglass.

Sounds like a plan.

Here's something...

When I read Scott's post, I was assuming that he'd glue in the ABS strips in an up-and-down fashion, parallel to the front of the hull (to avoid trying to bend them into the point of the hull).

But when I read Mark's plan, I'm assuming that you'll glue in the ABS strips horizontally, across the bend/point of the hull.

As you say Mark, with thinner strips, the bending & placing will be easier to manage, so either could work.

Pat.

My last ABS repair was meant to be a temporary fix - I picked up an old Blue Hole at the YMCA to take on a river trip and found that the outer ABS on a patch at the stern was gone, the foam eroded and sure to punch through on the first rock it hit. It was an area that would be covered by a grunch pad but I didn't have time to go get materials (it needed to be on the water the next day). So, I cut a piece of ABS to fit, put a generous layer of Goop on it and strapped it down with Gorilla tape. It worked great, even weathering some hard hits. I went to take it of yesterday to prep for a proper repair - I got the duct tape off but can't get the ABS off. I ran a thick bead of Goop around the edge and am going to leave it.

You can heat small sheets of ABS quite effectively and uniformly in a home style convection oven.
Here at work we use weld-on solvent adhesive for the ABS...works very well.

1) I am loving G/Flex right now. It is indeed very useful. It is more flexible than regular epoxy but it is extremely tough. It bonds well to both vinyl and abs ( though I think you'd be better off removing the vinyl here). I think you could find a way to make use of it in your application. You also have the added benefit of not having to worry about softening your existing hull. I have applied big d-ring patches with g/flex and experienced no softening, and the bond feels very strong.

One disadvantage to G/Flex is that it is not tacky during the working period as weldwood and vynabond are, so you'd have to devise a way to apply constant pressure to the repair until it cured. Oh, and its fairly expensive relative to regular epoxy.

2) You can avoid the use of acetone and the use of an oven for softening the abs. You can put it in boiling water.

What I might try in your situation is abs strips molded into the inside of the bow and glued in via G/flex. Then make a skid plate on the outside with glass and g/flex. The g/flex should be less likely to crack or pop off on impacts and hull flexing.

Alternatively, what about filling the dent with epoxy or g/flex and some type of filler till it was flush again? Then just sand/shape the outside of the boat to make a new bow tip and leave the dent on the inside. I bet this would work if the dent wasn't too huge. You could even then cover that with a skidplate.

I use g/flex to fill deep gouges in my royalex boats. I have never had it pop off and the rock wear resistance is excellent. I figured the filled areas would be sanded smooth by rocks within a couple trips, but they hardly show any marks (and have had plenty of interaction with rocks).

In addition, the West System G/Flex guide states that while not necessary (as is with hdpe) abs can be flame treated for increased bond strength.

Did I mention I really like G/Flex?

Lots of good advice here. Thanks everyone.

I was thinking of applying the ABS strips horizontally, like ribs. The bow has two small soft spots and about an 4" diameter area where it will easily cave in if it strikes a rock. So I just need to reinforce that particular area.

Might be a while before I get around to repair. Paddling takes precedence. But when I do, I'll report back with my results.

I wish I new about this sight before I tried outfitting my tripping canoe a couple of years ago. I used Vynabond to glue some tie down points and had no problems. But, in my hurry to get on the river, I glued on a couple of kneepads with Vynabond and did not let it dry. Needless to say, you know the result. I have two huge dents on the outside of my boat. It appears that the inner core melted and the royalex layers are now welded together. I've been told by the manufacturer (Nova Craft) that the strength has not been compromised, but boy is it ugly and no longer streamlined. Does anyone have a suggestion on how to fill these dents in? Anything would look better than how it does now.

Instead of trying to bend a thicker sheet of ABS using heat or acetone to fit the problem area, I have decided to do layers of thin ABS sheet.

Yesterday I cut a 5" x 16" strip out of a thin ABS sheet and glued it with g/flex on the inside of the boat over the soft spot. I taped it in place with some duct tape and then weighted it with a soft water bag to press the ABS into every contour and put a sand bag on top of that. The results look good. The sheet is firmly in place and I can feel that the soft soft now has a rigid backing. The U-shaped curve of the ABS provides extra strength and rigidity. All that flexes is the give in the Royalex from being a bit delaminated. My plan now is to glue two more thin sheets on top of the one I just installed to make it bomber. I'm then going to put a Rec Repair skid plate over the outside of the bow.

What are the actual thicknesses of the the "thick" sheet you didn't use and the "thin" sheet that you are using?

Pat.

After the fix, try putting an air bag on your bow, triggered by a proximity fuse of some sort.