Fiberglass Canoe Repair
Safety-PPE for fiberglass repair
Tools for a fiberglass repair
Fiberglass repair kits and materials
We have been going through some pretty hectic times over the last 12
months or so with fiberglass canoes being taken, a cyclone to contend
with (yet to
clean up properly), family dramas and surgery to boot, so please
forgive that this page does not
contain any pictures, we will get back to this in the near future.
So, if you are new to this, you should have
read the Getting started sections and made a list of tools,
materials and safety gear you will need to
set your self up for a fiberglass canoe repair.
Ok, so a fiberglass canoe hull thickness is generally
not very thick, so you will need to be
very careful when using the sander/grinder for this fiberglass repair,
but first get yourself
start our repair first make sure our fiberglass canoe is in a warm spot
of any cool/cold drafts, you could put the canoe on a set of saw horses
as this should give a good working height, prepsol down all around the
crack at least
300mm with a clean cotton rag to make clean and let dry.
Now depending on your finish and if your looking for a great finish, it
will be fast and much better to use a 2 pac spray finish, these can be
tinted to your requirements and used when your ready for your
fiberglass repair, they can be purchased from paint places that supply
the automotive and paint trades, some marine centers may also sell them
so give them a call before jumping in your set of wheels as this will
save you time and $ in case they do not have them.
So in order to get a good colour match you will need to polish a area
your damaged area and take a colour card to the canoe or if your
wanting the best match if possible take the canoe to your nearest
paint centre where they will colour match it for you, but this would be
the last resort.
The other more practical way is by using a clean sharp chisel bevel
side down and
working outward from the crack take out roughly a 4mm (3/16th) by say
32mm (11/4") round
type flat section with the canoes colour on, take that to your paint
where they will polish it up if needed, then tint the 2pac up for you.
You could ofcourse use
gel coat or gel coat paste, but this is not
going to be
good for the uninitiated unless we just have a scratch or chips in the
gelcoat but when when we are doing a fiberglass repair like this unless
the repair is only quite small and the reason is this, for gelcoat to
work properly it needs a little thickness so you will need to grind out
some of your laminate (that may make your repair weaker) and paying
attention to where it comes in contact with the original gelcoat egde
on the canoe.
If we are using Gelcoat repair paste it will dry hard and usually with
out a tacky surface which makes sanding a breeze, but if we are using
gelcoat in its liquid form it will be tacky when dry (thats its nature)
to get out of this you will need to spray or put some PVA, or a plastic
film to seal the surface as it drys , then wash off the PVA or peel off
the plastic film in order for it to be sandable.
Another way we could add a few drops or more of wax in styrene as we
mix up the gelcoat, this will make the gelcoat not tacky when dry
making sanding better, once the gelcoat is in and we start to sand this
is where (if you are not experience in doing this kind of work) you run
a big risk of sanding through showing up the laminate under neath cause
it was not deep enough to take gelcoat or you may see through the
gelcoat after you cut and polished it.
This is why the 2k or 2pac system is faster and better unless your a
traditionalist or the repair is on a new boat etc. and most pros
(unless the canoe is new) would opt for a 2pac finish anyway as gel
coat can be time consuming.
Ok lets get back on track, with a marker pen (white board maker is good) or pencil mark around the
fiberglass crack at least 50mm (2") all around and make sure the ends
round and 75mm (3") either end and don't bring to a point.
Using your grinder (in this case with 24grit disc) VERY CAREFULLY and
not applying much pressure to the grinder, grind out up to the outside
line where this is your feather edge, the crack is your deepest part
and be careful not grind right through your hull thickness.
The end result should be a even hollow dish like appearance with little
or no humps or deep hollows through out this area, now do not touch any
part of this with your fingers or hands or get it contaminated.
Using a clean no lint rag (white cotton) or compressed air, dust around
the outside and get rid of any dust near your repair.
Cut your first layer of mat (if you have not done so already) about
25mm (1") in width and past the length of the fiberglass crack either
end by around 20mm, now do the same for your second piece making sure
it is wider and a bit
longer to overlap the first e.g 50mm (2") in width.
Do the same with the third or forth piece of mat, the idea here is to
fill the hollow with overlapping layers of fiberglass mat with the last
hitting near the feather edge (where colour meets the raw sanded/ground
fiberglass, by rights you should at least have one layer of a heavier
grade mat layerd in between as fiberglass repair kits usually come with
450grm csm mat and not 600 grm csm, but this is not totally necessary
for a canoe repair, now put these in order with the 25mm width mat
first (as this layer is the first to go down) with the widest one last.
Mix up a small test batch of resin with catalyst (hardener) according
to the instructions on the tin and watch the time it starts to gel
(approx 20mins) if your happy with the time (or according to the
instructions in your kit) you can now start to mix up your real batch
of resin and mix well, making sure you stir from the outside to the
inside of the container and visa versa so
that the resin/cataylst is mixed well.
With gloves on, lay a wet layer of resin over your damaged area and lay
down your first piece of matting having the crack in centre of mat and
dampen down making sure that each end overlaps and
interweaves to the next following piece if your fiberglass crack is
long, be quick and not chat, wet out
this piece and lightly roll over it to remove any air bubbles or work
it with your brush.
Your mixed resin should still be fine and ready for the next layer
overlapping the first evenly as possible, making sure you do not match
up with your ends as you need to stagger these throughout,
except the very ends of the crack, just overlap the other.
Quickly working, wet this layer out and working your brush lightly from
side to side even out the layer or use a paddle roller to easily and
quickly lightly work it level,
If time and resin is ok lay down your third or last layer (you may need
to mix up a new batch of resin to finish the job depending on the size
or if the resin in your
tin has started to gel, use a new tin and wash out your brush with some
acetone to keep from jelling up) and continue if need be.
When the fiberglass repair work is done, wash out your paddle roller
using a roller) and your brush and let your job set up till hard.
Now if any crack is showing on the inside of the fiberglass canoe this
can be repeated and finished off like the outside.
Next using your grinder with the same disc on very carefuly run over
the glassed area to level off any high areas and any hairy glass fibres
that may be there, you can use your hand carefully to feel for any high
spots and can be a good idea to use cloves when doing this as
fiberglass splinters can be sharp.
Now using a flexible plastic ruler on its flat or similar and starting
from one end bend it to the fiberglass canoes curve, slowly bring it
through, the fiberglass repair should be just level or just under, any
can be sanded down.
Prepsol or clean off the area wearing gloves not to contaminate this
area and let dry well, mix up your filler (a test mix is good first)
and trowel it
through using a flexible spatula or a flexible plastic filler card from
one end to the other evenly and slightly raised if posible, let dry
hard before trying to sand.
Now using your cork/rubber block and 80grit sandpaper and following the
fiberglass canoes curve (unless your on a flat section) knock off all
filler, now using a 150grit knock out the scratches of the 80grit and
continue to level.
At this point if there is any hollows or pin holes,
prepsol this down, let air out (dry) and fill with some filler
before sanding any more.
When dry, continue to lightly sand (don't worry if your starting to
lightly sand into your colour) now feel with your hand it should marry
into the outer colour pretty evenly, any light high spot can be lightly
to marry in.
With your 240 grit take out the 150grit scratches and dull off the
surrounding colour it should now feel nice and even like if your
feeling any other part of the canoe, now if your happy with it, dust
all around and wipe over all the areas with prepsol or similar with a
clean cotton rag.
dry our fiberglass repair can now be prepared for applying the primer,
you will need a roll of masking tape and newspaper or you can buy the
masking tape already stuck to a brown paper roll which makes it pretty
easy to paper up.
Now starting at least 75mm (3") around your fiberglass repair, wipe
lightly over and up to to the masking tape with prepsol and let dry
Shake up your can of primer and if you have not used a spray can before
have a little play on some scrap tin or something similar till your
confident, make sure like all things to read the spray cans
instructions before use and use in a ventilated area.
Spray a light even coat of primer over the repair but do not go
anywhere near to the masking tape, just keep it just over the repaired
sanded area, do a second coat heavier this time, let set and a last one
should be the same but don't do it too heavier as you will get runs and
feather all coats to the outer but covering the repaired sanded
Undo all paper and masking tape and ditch it, when primer is all hard
you can lightly sand all over with 240grit followed by 320grit and
600grit into the coloured area, don't be too concerned if you can
lighly see through the primer in some areas.
Wash down with some light soapy water and let dry, now mask and paper
up the same as before but leaving more area from the primer to the
Lightly prepsol down and let dry, shake and mix up you top coat as per
instructions on the can and do a test spray patten somewhere to see how
it looks and get an idea of usage.
Now lightly evenly spray your first coat over the primer, let tack off
and follow another coat through overlapping the first and heavier, let
tack off, now give a last coat which should be beautifully glossy and
solid colour with little over spray anywhere near the masking tape and
let dry, just before dry remove the paper and masking tape gently
taking it off away from your sprayed area, let all now dry hard.
have a little overspray you can use
some 1200 grit wetndry and some light soapy water followed by 2000 grit
down then polish in when dry, make
sure its done a few days or a week after as
the 2pac may not gloss well when cut and polished into the surrounding
when you did it e.g winter.
So we hope that this fiberglass canoe repair will put you back onto the water and happily canoeing.
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