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Every
paddler, no matter how proficient, will have to repair a kayak at some
stage or other. Some can afford the luxury of dropping off the damaged
boat at a reputable manufacturer to be repaired. But for most paddlers,
it’s a case of do-it-yourself. So here are some basics of boat
repairs, divided into two sections.
Part one will look
at controlled repairs done at home, while part two covers the emergency
repairs that can be carried out during a race on a seriously damaged
kayak.
Part One – Controlled repairs
This is often a pre- season chore for many paddlers. Fixing up the small
“dings”, spider cracks, cockpit damage and removing old patches that
might have come loose to some degree. The be able to do this
effectively, you will need :
1 kg General Purpose resin
Bottle of catalyst
Chop-strand fiberglass matt
An empty bottle or tin that can take 500 ml of liquid
A 50m wide paintbrush
Sandpaper, coarse and fine grit
A drill fitted with a sanding disk – again coarse and fine grit
sandpaper OR
A hand rasp
1 litre of Acetone
A disposable stirring stick
OPTIONAL:
Gelcoat
Rubber gloves
Plastic shopping bags
Gas burner
Scale
Prepare the area to be repaired. Using coarse sandpaper, or a drill with
a sanding disk, start grinding, rasping or sanding away the area of the
damage, and an areas at least 50mm around it. On the inside of the boat,
you can sand down to the fiberglass cloth. On the outside of the boat,
grind away the smooth gelcoat exterior until you have a roughened area
that exposes the fibreglass cloth. The purpose here is firstly to remove
any old broken fibreglass that is no longer needed, and secondly to
provide a coarse surface for the resin to bind onto suitably.
Try as far as possible to do all repairs on the inside of the hull. All
exterior repairs are prone to snagging on rocks and can often come
loose. Sometimes damage to the nose and tail areas can not be easily
repaired from the inside of the boat, so there is no real option but to
repair on the outside of the hull. But for all areas that can be reached
from the inside of the boat, plan to put the patches on the inside of
the boat.
If the damage is so serious that the boat has bent out of shape, then it
is important to make up a splint to reshape the area into the desired
shape. You can do this with wooden sticks taped against hull. If the
damage is really serious (i.e. from a major “wrap” in which part of
the boat has been lost), then the boat will have to go back into the
original mould, and will have to be taken back to whoever made it.
Then, prepare the chop-strand fibreglass matting for the repair. Take
the sheet of chop-strand, and tear a piece off with your hands. Don’t
cut it with scissors, as this forms a hard thick edge to the
chop-strand, whereas a hand-tear forms a much softer, smoother edge.
Tear a piece that will cover each damaged section and overlap 50 mm.
Then it is time to make up the resin mix. If you have an old kitchen
scale that you can use, this allows for accurate weighing of the resin.
This is very important, as the amount of catalyst you add has a major
effect on the quality and strength of the repair. Place the tin or glass
jar that you will use for the resin mix on the scale, reset the dial to
zero, and then add enough resin, plus ten percent, to do the repair.
Don’t underestimate! Rather throw out spare resin mix, than have to
run back and make more!
Resins vary, quite a bit, so please read the mixing instructions on the
tin carefully. Generally, you have to add 1 gram of catalyst to 100
grams of resin (a 1% mix). One gram of catalyst is about 20 drops. Some
resins can offer a stronger catalyst mix (1-2% for example), but please
bear in mind that the slower the mix (less catalyst), the stronger and
more flexible the final repair job. Faster (or “hotter” mixes) will
dry quicker and harder, but will be more rigid, less flexible and more
likely to come loose in the long run. Resin dries faster in hot weather
(and conversely, slowly in cold wet weather), so take this into account
when you prepare the mix!
Once you have added the required number of drops of catalyst to the
resin, and stirred it WELL with the stirring stick (the catalyst must
reach all the resin!), you have about twenty minutes to do the repair
before it starts hardening. This is weather dependent as well.
Start by painting a generous coating of resin with the paintbrush over
the entire area that has been sanded in preparation for the job, and
work the resin into the roughened area and exposed cloth. Then place the
chop-strand matt onto the repair area, and press it into the wet resin
with the paint brush.
Once it has all stuck in place, start at one end and work it into the
wet resin thoroughly with the brush, adding extra resin if needed, until
all the chop-strand is clear, and there are no white areas visible. Make
sure there are no ends ticking out from the repair job.
Make sure that enough resin has been used to saturate all the
chop-strand matting, but also make sure that there isn’t any surplus
resin that might pool on top of the repair job, or run down the surface
of it.
The repair job will start drying in twenty minutes, but it is best to
leave it a full 24 fours before doing the next step. Leave the repair to
dry in the sun, as this helps dry the resin that is not absorbed by the
chop-strand.
Then, clean the brush with acetone, and clean any resin of your hands
(and anywhere else) with the acetone. Make sure to wash your skin with
normal soap or dishwasher after the acetone clean, as the acetone can be
quite harsh on the skin!
Once it is dry, you should be able to get the boat back into service
right away. Sometimes the repair might need another session. In this
case, go about it the same way : Sand down, prepare, resin and let dry.
If you need to hurry up the drying process, or if the surface is still
tacky a day later, you can use a gas-blowtorch (the camping gas type
used for welding or plumbing soldering) to dry up the resin. But
remember that when you resort to this tactics, you will be making the
repair job a lot more brittle.
TIPS:
If you cant get your hands on any acetone, try washing your brushes with
normal washing powder or Handy Andy. For some reason ,this breaks down
the resin really well, allowing you to clean the brushes for re-use.
For a smooth finish to a key area, such as the outside of the hull, or
the cockpit lip, take a piece of plastic shopping packet and stretch it
over the repair while it is still wet. Smooth the plastic as much as
possible. Once dry, it will peel loose easily, and create a pleasing
smooth finish that wont snag onto anything.
If you want to finish up the job with a glossy smooth surface,
especially on the outside of the hull, then you can add a layer of
gelcoat. This looks a lot like resin, but is jelly-fish in texture. You
add catalyst, as described on the instructions, and paint it onto the
exterior, after having roughened the areas well with sandpaper. The
gelcoat, once applied, mustn’t be re-brushed, as it forms a cohesive
skin, and finally, a very pleasing smooth, and tough surface. Great for
rebuilding the nose of your boat, after all those small dings and
collision with rocks!
Good Luck!
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