I have just taken delivery of two Impex Carbon/Kevlar kayaks that unfortunately they have manage to damage in trasport (air courier).
The hull shows cracks but the fabric is not torn.
There are some weak spots on some of the cracks.
I undestand that Kevlar is mighty strong and that the hull is not really weakened structurally by the 1" to 2" cracks but I would like to fix the kayaks since they are brand new.
How do I go about fixing the cracks in the clear coat finish? is there such thing as “clear gel coat” or is the finish something else?
Any expert advice would be very appreciated.
Gnarlydog
crack repair in C/K hull
because you mention that the cracked areas are softer, I’m guessing you have what we call stress cracks - that show as lighter areas in the kevlar. Basically, the kevlar held but the resin shattered.
Ask Impex for a matching/compatible resin and gel.
Surface prep by masking off an area 3cm back from the stress crack. Sand, clean with acetone, pull the tape and catalyze the resin. Have gloves, respirator and wear an apron or cloths you are ready to discard.
Using a brush, wet the area with resin and patch on the inside with a first kevlar/twaron patch that is 1,5 cm larger than the crack, then cover that parch with a larger patch, 1.5 cm larger in all directions than the first broke. Cover with a peel ply patch that is 1cm wider than the last patch.
When the resin has hardened, pull the peel ply patches.
Exterior, gel repair can be time consuming but us also straightforward. Using a knife, pick out every bit if broken. loose gel possible.
Catalyze an appropriate amount of gel, daub it onto the exposed cracks so it is proud and wait for it to harden. Sand flush with 80, then 120, then 220 grit dry paper, carefully minimizing the sanded area and eliminating all previous scratches with successive grits. Then switch to wet sandpaper400, 800, 1200 grit, before using rubbing compound.
make your life easier
and just use fibreglass for the interior repair.
Glass verse Kev patches
Kinda depends on your experience and what you want the hull to do afterwards.
FGlas is easy to cut and the raised patch edges sand out easily. FG patches are stiff, the balance of the hull interior is ~ flexible Kev, so you’re mixing characteristics.
A single layer FG patch will, if peel plied, almost disappear, which is good if it is strong enough.
Dual Kevlar patches are tough to cut, [use a safety razor blade on a soft pine board], and the edges impossible to sand out. That’s why professionals use peel ply. That said, that’s the better way to repair a stress crack in inner Kevlar blankets.
I think I must be the champion at
cutting Kevlar patches with cheap scissors. Still, I’ll have to try the razor blade approach.
clear gel coat?
When CEWilson says: >>Catalyze an appropriate amount of gel, daub it onto the exposed cracks so it is proud and wait for it to harden…
clear gel
Your mention of cracks suggested the outer surface was clear gel. We use Cook CP MC963XA220, which is available in 5, 25 and 55 gal quantities. Try Minicraft for smaller amounts if your manufacturer won’t deliver repair materials.