Firstly, thanks for the really useful video on kayak repair! 

What a great resource.

I have two kayaks and three sets of blades which need a variety of patches, and your video has given me the knowledge to start the boat repairs at least!  I like the links to the relevant supplies.

Keying the surface

Is sandpapering adequate or is a better bond created if you sand right back to the carbon kevlar until it is 'fluffy'?  In my local club many people use angle grinders to take back the material this far (risky I know but it appears to be fine if you are delicate); from a structural / bonding point of view is this better than abrasing the existing gel coat and attaching the patch to that?

Advice on other repairs / videos which would be great

They aren't quite as bad as they sound, and I'd rather repair than buy a new kayak.  Most of this kit was acquired second or third hand!! 

I can upload detailed photos of the following problems if this would help you to provide advice on how best to repair:

1. Large area of delaminated / cracked gel coat - I have a large area (about 1m x 40cm) where the gel coat was coming away so I've sanded this back to the 'fluffy' carbon kevlar.  Is there a way to apply a gel coat effectively to a large area or should I just liberally paint it on?

2. Hairline cracks in gel coat - I have a number of hairline cracks (due to age and perhaps too much sun) in my older boat's gel coat.  The underlying material is good and strong.  Is it worth doing anything with this, e.g. brush some epoxy over the top??  Is it likely to be letting water in?

3. Full nose rebuild - The nose on one of my kayaks is very badly damaged - the previous patch has come totally away leaving a big hole.  How would you recommend patching this?  Is there a way to build a nose first then 'transplant' it?  I've heard you can use a balloon to create a shape to mould the end around.

4. Seam not split but not flush at edge - the seam is still holding the boat together but it has come away at one edge leaving a very sharp and rigid ridge about 1-2mm from the hull.  What is the best way to blend this back in? Should I somehow fill the gap or should I overlay another peice of seam tape to bridge the gap? (The sharp ridge runs along most of the length of the boat so I'd rather avoid an additional seam on top if possible).  I'm very reluctant to re-do the seam as the previous owner had it sent back 3 times because of the seam continuously popping

5. Paddle repair - edge split - I have one paddle with a split edge (you can actually see the inside of the blade).  Is seam tape the best way to cover this or will epoxy alone work?

6. Paddle repair - flex on front face - I have one paddle where half the carbon blade face flexes 5 degs towards my hand.  Is the best way to patch this by putting some layers of carbon on the rear of the blade, running across the line of the flex and in the direction of the shaft?  Should I use carbon, or can I use left over carbon kevlar from the boat repairs?  I have this same problem on an older blade where I'm not sure of the construction (it appears to have a foam core and a very thin (single) layer of carbon fibre on top)

7. Seat refit / adjustment - my seat is coming away on one side where it attaches to the canoe.  Can this be fixed with little repair strips?  Ideally I'd like to move the seat back at the same time but I have no idea where to cut the carbon kevlar to get it out (and it's very fiddly in terms of getting a cutting tool in there), nor how to fix it back into position.  Any advice?

8. Bumper removal and refit - Not technically a repair as such, but I notice in the demo video how clean the edge seal is around the nose.  Do you have any tips on how to remove and refit a bumper effectively and especially how to remove all the crud that stays stuck on?  I've only tried it once and the bumper ended up disintegrating.

Many thanks in advance, and sorry for so many questions! 

Great tutorial. I have just purchased a carbon/kevlar boat which has a couple of areas which might need the epoxy resin restoring.

Hi Maggie,

No, there is no 'design fault'. The Kayak itself is made from a carbon/Kevlar hybrid fabric. The repair is made from a matching carbon/kevlar hybrid. Kevlar, like Dyneema, is a high tenacity synthetic fibre. In fact, Kevlar (and other Aramid fibres) are much more common in canoe and kayak production than Dyneema. The repair we've made in this video is perfectly suited to the job and will provide the stiffness and impact resistance neccessary to keep this hull strong for years.

Dyneema (or more likely a UHMWPE fibre from another manufacturer) is a very interesting fibre with impressive elongation-to-break and abrasion resistant properties but, as you've alluded to, it is extremely difficult to bond to and generally needs to be used layered between reinforcement that is easier to bond to. There is no incompatibilty between our epoxy and UHMWPE fibre any more than there is with most epoxies and UHMWPE; this type of fibre is just very difficult for resin matrixes to bond to (you can completely forget polyester and most vinylesters).

One thing I can say for sure, this repair will be sound and virtualy all such repairs (and the majority of boat constructions in the first place) use glass, carbon, carbon/aramid, or diolen. Dyneema hulls exist but they need to be carefully designed to exploit the properties of the fibre whilst circumnavigating its dissadvantages.

I hope this clarifies the situation for you.

Best regards, Matt


Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Interest video.

Is there not a design fault here  however ?. The repair may not be strong enough for this customers application.

Should the KAYAK not have been repaired using carbon/dyneema fabric to absorb the shocks or is there a compatibility problem with easy composites resins because of the dyneema content

                                                                                                                                                                                                                            Regards,

                                                                                                                                                                                                                                        Maggie

As a paddler I've learned that one by trial and epic error!  What would be REALLY useful would be a similar one for foam cored boats where you cant get down inside to adequately repair the inside skin.  I imagine you'd have to sand out the foam, refoam, and patch the outer skin??

I love the old revenge.  Top polo boat!

Sorry to dissapoint, in the end i brought an undamaged boat. But thanks for the info i may need it in the future.

Hi Fubarvader,

Yes, you could certainly repair a whole hull in the way that we do the small patch in the video. You would have  alot more areas to pay attention to though so when doing the filming and squaeegying through you would indeed need a much slower resin/hardener. I would suggest our EL2 laminating resin using the SLOW hardener. This will give you at least 1-2hrs working time on the hull (once the resin has been spread out over the hull it will slow the reaction down considerably) whilst you get it wet through properly, filmed pulled tight and any air bubbles worked out of it.

The cure time on the EL2 using a slow hardener will then be very slow (like 24hrs) but I this is well worth it to ensure that the resin doesn't start curing on your whilst you're still working on the hull.

I hope this helps. Post some pics of the project because it sounds interesting.

Best regards, Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Hi

I am looking to buy a second hand boat with similar damage through out the underside of the hull. Is it possible to repair the breakthrough's just as you have done then cover the complete underside to give the impression of a new hull, using the method you have described?

The repair media would be black diolen, with an expoxy that hopefully cures a bit slower.

cheers

Thanks, reasonably conventional stuff but have quite a bit of experience of this kind of repair and so I like to think we've provided some better advice than is generally out there.

RE the boat; it's one of our customers, he's a keen water polo player and I think pretty hefty collisions are a daily occurence. He came in for some advice about how to do the repair and we said if he leant us the Kayak for a few days we'd do the repair and make a video at the same time.

Stay tuned for some more of our advanced composites vids. They're a little way off because it's another whole series but as ever, we hope it will be worth it!

Matt

Matt Statham
Easy Composites / Carbon Mods - Technical Sales

Another cracking video! So who is into Kayaking and had a "Whoopsie" moment?