Crack in Canoe - Fibreglass Repair Kit??

[velvetmonkey]

Hi there,

I have recently put a fist size dent and 6 inch crack in my Mad River Explorer 16TT canoe (accidentally of course!!!)
Have been advised to heat the area and "encourage" it flat again - sand it down and apply a fibreglass repair kit.

Problem being - not sure what sort of kit to go for.......

Any suggestions?

Thanks

[Dave]

Melted Lego Bricks apparently works for ABS canoes.

[laro13]

And drill a small hole in the ends of the crack, so it does not get bigger.

good luck.

[Marmite]

+1 on the advice to drill a small hole in either end of the crack as its the only way to prevent it getting longer.

Wenonah, voyager, bell, mad river and old town all do purpose built repair kits which should contain woven fibreglass sheet (not the chop mat rubbish), epoxy, hardener, mixing pots, jumbo lolly sticks and a long pair of disposable gloves. Some even come with a dye you can add to the epoxy for an approximate colour match. I even used a plastimo kit once when helping to repair a friends boat on the south coast as there were no good canoe shops locally and Internet would have taken to long.
The one extra piece of kit I've found handy for doing repairs is a small decorating roller with a solid plastic barrel (no fluff) as you can get all the air bubbles out from under the patch when applying it (remember you'll want 2-3 layers on the outside and 1-2 on the inside of the split).
If you need any other advice you'll find loads on the "song of the paddle" forum under repairs (I would have tried to post a link but as an absolute newbie to this, I have no idea how to- sorry) or leave another post
Hope this helps and good luck.

[ged]

Apparently they aren't all made of the same material, but if it's polythene there are welding sets about that will repair it. Getting anything like fibreglass to stick to it could be a problem. A hot air gun with a fine nozzle might do the job if you're careful.

[Scots_Charles_River]

Good luck,

http://www.google.co.uk/webhp?source...w=1280&bih=685

[scoops_uk]

I would drill a tiny hole either end, as said to stop the crack growing. I would then use an epoxy resin to fill the crack (and holes). Mix the resin as instructed (adding the incorrect amount of hardener will weaken the cured resin) and ideally add 2 parts colloidal silica to one part mixed resin (this will make a thick peanut butter like paste).

Edited to add: I'd avoid polyester (fibreglass) resins as they have poor adhesive qualities compared with epoxy.

I'm a boat builder by profession.

Scoops

[Dogoak]

There's a few threads over on SOTP.............http://www.songofthepaddle.co.uk/forum/forum.php

The repair will depend on the composition of the boat.

[santaman2000]

I would drill a tiny hole either end, as said to stop the crack growing. I would then use an epoxy resin to fill the crack (and holes). Mix the resin as instructed (adding the incorrect amount of hardener will weaken the cured resin) and ideally add 2 parts colloidal silica to one part mixed resin (this will make a thick peanut butter like paste).

Edited to add: I'd avoid polyester (fibreglass) resins as they have poor adhesive qualities compared with epoxy.

I'm a boat builder by profession.

Scoops

I prefer epoxy resins too. That said, fiferglass repairs aren't restricted to poly resins, and haven't been for several decades. When I was still repairing aircraft, the technical orders often stipulated epoxy resins on fiberglass. Poly resins aren't usually suitable for radomes as they're not radio transparent enough; 75% compared to epoxy's 98%.

[scoops_uk]

fiberglass repairs aren't restricted to poly resins

You're quite correct, although I never actually said they were. From the perspective of a layperson, fiberglass is widely understood as the combination of glass reinforcement in a polyester resin, hence my adding the term in brackets.

It's worth adding that if a re-inforcement cloth is used, it ought to be compatible with the resin being used.

Scoops

[santaman2000]

You're quite correct, although I never actually said they were. From the perspective of a layperson, fiberglass is widely understood as the combination of glass reinforcement in a polyester resin, hence my adding the term in brackets.

It's worth adding that if a re-inforcement cloth is used, it ought to be compatible with the resin being used.

Scoops

Fair enough. But I'm still a bit confused; are you saying here that fiberglass filler/re-inforcement isn't compatable with epoxy?

[scoops_uk]

Don't want to get too complicated. Obvious example, some chopped strand matting is held together with a binder that is dissolved by the styrene in a polyester resin to allow consolidation of the layup. If you used an epoxy resin, which contains no styrene, you wouldn't get the binder dissolving in the same way.

I'm simply saying that you cannot freely intermix components intended for one resin type with another, you need to check they are compatible first.

Scoops

[santaman2000]

Don't want to get too complicated. Obvious example, some chopped strand matting is held together with a binder that is dissolved by the styrene in a polyester resin to allow consolidation of the layup. If you used an epoxy resin, which contains no styrene, you wouldn't get the binder dissolving in the same way.

I'm simply saying that you cannot freely intermix components intended for one resin type with another, you need to check they are compatible first.

Scoops

What you're describing is what we call "matte mold" and we frequently used it with epoxy resin. Worked fine on F111s, F4s, and KC135s. Probably other aircraft too but those are the only ones I did fiberglass work on. Not that I'd want to do a fiberglass repair over a plastic hull though.

[scoops_uk]

What you're describing is what we call "matte mold" and we frequently used it with epoxy resin. Worked fine on F111s, F4s, and KC135s.

Sorry, I clearly said "some" chopped strand matting not "all". I'm simply trying to guide the OP into choosing compatible components for his repair based on what is readily available on the UK market not add to any confusion.

[velvetmonkey]

Thanks to all your response, but must say, I'm completely lost!

I'm taking from your advise that fibreglass isn't the way to go?
I've heard epoxy resin is quite expensive - given the size of the crack I'd be loather to spring for a full tub....

The manufacturer's website endorses the "poly drip" method, i.e. melting a polyethylene strip onto the flamed and sanded crack (similar to Dave's melted Lego suggestion?). Their website also warns against fibreglass repair?

This leaves me wondering - where to get a polyethylene strip??
Are Lego bricks really an option?

Totally confused and hoping for a miracle!

[santaman2000]

Sorry, I clearly said "some" chopped strand matting not "all". I'm simply trying to guide the OP into choosing compatible components for his repair based on what is readily available on the UK market not add to any confusion.

Fair enough. I didn't think fiberglass materials or epoxy resin would have been difficult to source (or overly expensive) but I haven't lived over there for over 23 years now.

[scoops_uk]

The manufacturer's website endorses the "poly drip" method, i.e. melting a polyethylene strip onto the flamed and sanded crack (similar to Dave's melted Lego suggestion?). Their website also warns against fibreglass repair?

This leaves me wondering - where to get a polyethylene strip??

If they recommend the poly drip try that. The first time you try it doesn't have to be on the boat, have a play.

"Fibreglass" by which I assume they mean a polyester resin based system, has poor adhesive qualities which will be why it is advised against.

The "Mad River" repair kit looks like an epoxy resin and a bit of cloth. Epoxy resins have much better adhesive properties. The epoxy repair kit I linked to above is £15 which isn't too expensive. You may wish to purchase a small length of glass tape (or PM me your address and the length you need).

Don't be scared of the repair. Making a watertight repair is almost a given, making it look pretty might take a little more patience.

Scoops

[Scots_Charles_River]

Thanks to all your response, but must say, I'm completely lost!

I'm taking from your advise that fibreglass isn't the way to go?
I've heard epoxy resin is quite expensive - given the size of the crack I'd be loather to spring for a full tub....

The manufacturer's website endorses the "poly drip" method, i.e. melting a polyethylene strip onto the flamed and sanded crack (similar to Dave's melted Lego suggestion?). Their website also warns against fibreglass repair?

This leaves me wondering - where to get a polyethylene strip??
Are Lego bricks really an option?

Totally confused and hoping for a miracle!

The bang plate kits might work. As long as they match that plastic. www.endlessriver.co.uk send a wee email off.

Epoxy is stickier and more flexible once hardened, compared to GRP type fibrelgass mat and polyester. So getting whatever you use to stay stuck the the hull will be key.

It's easier with a single skin hull like a WW kayak as you just weld it with plastic, normally folk take a slither off the cockpit rim with a razor blade.

[ged]

... This leaves me wondering - where to get a polyethylene strip??
Are Lego bricks really an option?

Totally confused and hoping for a miracle!

First things first. Dogoak got it right when he said

The repair will depend on the composition of the boat.

You haven't told us what the material of the boat is yet. If it's plywood for example, things might be different from if it's made of glass fibre reinforced polyester resin.

So to begin with you need to know what the boat is made of. As I said in my first post, it looks like these boats are made in more than one material but I don't know much about them.

Find out what material your boat is made of.

Polythene is very easy to mould and to repair. It's also very easy to find, for example polythene bags are (unsurprisingly) made of polythene. The trouble is they might have unwanted additives in them such as fillers for colour or even things to make the polythene break down in sunlight so you might need to be careful how you source the material(s) you use for the repair. Oh - Dyneema is polythene.

But don't get hung up on the details of the repair before you know what it is that you're repairing. As I said, polythene isn't the easiest thing in the world to get things to stick to but it's easily weldable with the right tools and techniques.

If you're completely, er, out of your depth you might just have to pay someone to do it. Can we take it that it's not covered on your house insurance or something like that?

[santaman2000]

I had to google polythene to be sure it was the same thing as we call polyethylene.

[ged]

I had to google polythene to be sure it was the same thing as we call polyethylene.

Two nations divided by a common language.

[Scots_Charles_River]

Aye, or a 'poly bag'

[norca]

http://www.westsystem.com/ss/g-flex-epoxy/ look at the canoe repair at bottom looks good stuff

[velvetmonkey]

Once again, thanks to all who have taken the time to reply.

According to website, the canoe is made from a "triple tough" system - a foam core centre sandwiched between two layers of polyethylene.

Thanks to Scoops and other for the links to epoxy resins - I think I'll go ahead and order a kit.

I intend to heat treat the affected area, and "persuade" it back into shape.
I'll then sand it down.
Question is, should I then mix up some resin/hardener and fill any gaps and let that dry, before applying the fibreglass tape?

[Scots_Charles_River]

The fibreglass tape needs to bond/glue/stick to the plastic, it needs soaked in epoxy too.

[scoops_uk]

Question is, should I then mix up some resin/hardener and fill any gaps and let that dry, before applying the fibreglass tape?

I would do this as a 'wet on wet' repair....

Roughen the repair area and wipe clean with some acetone.

Mix some epoxy thickened with colloidal silica (mix a small batch of epoxy as directed say 50ml, easy maths with the 5:1 ratio for West Epoxy) then add approx the same volume again of silica into the cup. Mix thoroughly and wear a dust mask, silica is best kept out of your lungs! I would then use a spreader to push the thickened epoxy over and around the repair area with the specific aim of working as much as possible into the crack. You won't use all the epoxy you have mixed. Do this on the inside and outside of the hull.

Then apply some tape to the crack on both sides. I would use a lightweight tape for this job to reduce it's cosmetic impact, say 100-150g/m 50mm wide tape. If you pre-cut the tape beforehand it will save getting into a sticky mess with scissors now.

Mix a fresh similar sized batch of epoxy, this time unthickened. Using a 1" disposable brush (it helps to cut off half the length of the bristles to stiffen the brush) stipple the unthickened epoxy into the cloth over the repair area. The tape should go clear as it is saturated with the resin. Try to get a good neat wet out of the tape without flooding the area with masses of resin. Ideally you want a nice smooth surface just filling the weave of the cloth. You have plenty of working time to do this right on a small repair and the epoxy will flow and level itself a little.

I'm guessing your boat is painted. Before overpainting the epoxy you will need to remove the 'amine blush' this is a waxy surface layer created as the epoxy cures. This can be removed by lightly sanding with some wet and dry or with soapy water and a green pot scouring pad. Use wet and dry to try and get as fair (smooth in line with the curves of the boat) a finish as possible, but go slow and be very careful it is so easy to sand too much and make things worse!

Epoxy and silica etc can be nasty stuff. Please wear eye protection, disposable gloves throughout and a dust mask when the silica is unmixed.

Scoops

[velvetmonkey]

Scoops,

Just about to order the West epoxy kit.
I'll be able to get some glass tape from work, as well as fibreglass cloth - where would I get silica??

[ged]

Scoops,

Just about to order the West epoxy kit.
I'll be able to get some glass tape from work, as well as fibreglass cloth - where would I get silica??

Silica is the most common material on the planet so it isn't hard to find. Some people call it sand.

But if you want something a bit more special you can try a search engine. Third hit on Bing for example:

http://www.cfsnet.co.uk/acatalog/CFS...ilica_402.html

You'll save yourself an awful lot of time and trouble if you learn to find things like this for yourself.

[Sweden]

If you chop up some of the fiber cloth and mix that with the resin going in the crack, it ill add strenght to the resin.