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On Wed, 27 May 1998 08:54:55 GMT, (K
Smith) wrote:

Dwayne,

This is a very labour intensive repair, but doesn't require any
particular "skills", other than patience. This is a newsgroup so here is
how it is done.

Firstly I take it this boat is significantly cheaper than equivalents,
because of the high cost of paying for labour to do the job & most
importantly the "crazing" is definitely only in the gel coat. Sometimes
the crazing is the symptom of a structural problem inside, not usually
just sometimes, but it is best you're aware & look for concentrated
crazing on the outside, around areas like where the anchor well, floors,
bulkheads & other are joined to the skin, if so it should be
investigated closely.

OK on the assumption you are reasonably good with your hands;

1) You'll need a flat foot sander, various cheap disposable paint
brushes (wood not plastic handles), some disposable containers (2 litre
ice cream type), some micro-balloons (Q-cells), enough "gelcoat" the
same (or very close) colour as the hull. (Your supplier of Gelcoat
should be able to "match" the colour closely but it will change with
age, so don't expect a perfect match & be guided by the supplier),
catalyst for the gelcoat, 2 ltrs of acetone, 2 ltrs of PVA, grit paper
for the flat shoe sander, as follows 80 grit,120 grit, then some 400 &
1200 grade wet & dry, gelcoat cutting compound & wear rubber gloves
(washing up or disposable)

2) You need to thoroughly clean & dry the entire area, then sand it
with the 80 grit flat shoe sander, (don't overdo it) this will break up
any loose gelcoat & completely eliminate any remaining gloss. Keep it
dry & clean.

3) Mix up a small amount of gelcoat with a little micro-balloons,
adding micro-balloons until you get a paste about the consistency of
cream cheese (phily) & add 1% by weight of catalyst in an ice cream
container. Time how long it takes to go off, (start to harden) it should
be about 20 mins, if not do it again with a little more or less catalyst
as appropriate, note the amount & stay with it, unless there is a big
weather change.

(4) Now mix up a small portion of the gelcoat & micro-balloon mixture
(about 1/2 an ice cream container then catalyse at your percentage as
found in 3 above)

(5) Apply the mixture over the area concerned, work quickly so you have
plenty of time to ensure it is "worked" into the surface left by the 80
grit paper, don't mix anymore yet. (put brushes, applicators etc in acetone)

(6) Time it & at about 15 mins, you'll notice the mix starts to go hard
(like cheddar cheese) & be slightly tacky to touch but this is normal,
at this stage give it a good wipe with acetone to remove the tackiness.
(you won't get rid of it all, resins don't properly cure when exposed to
air, but most)

(7) Now sand it with the 120 grit, you only have about 5-10 mins to do
this (that's why you only mix about 1/2 an ice cream cont. at a time) or
it will become too hard, (if it does, sand it again with 80 grit &
repeat). You should sand it until the original surface is just becoming
visible, don't leave too much build up, nor sand it all off. You may
need to repeat this a couple of times until you get a good flat surface
& you're confident with the process. Now proceed to do the neighbouring
areas one at a time until the whole area is done & sanded. Keep
everything dry & clean.

(8) Now you'll need enough gelcoat (no micro-balloons) to cover the
entire job as thickly as you can get it to stay without runs or sags.
(don't allow any because they're almost impossible to sand out, cured
gelcoat is hard) but you can mix small amounts at a time (i.e. don't
catalyse the whole lot at once) add the right amount of catalyst for the
amount of resin & apply, feathering out where the repair meets the old
surface. Cover the area with the PVA (ideally this should be sprayed over
the wet gelcoat, but you will get it on with a brush if you wait until
the gelcoat has just started to go off)

(9) After about 8--12 hrs, (overnight, not much longer as it keeps
getting harder to sand the longer it cures) completely wash the PVA off
with water, then with the flat foot sander & now the 400 wet & dry, sand
it with a little water, obviously for safety, if your
sander is electric be very careful & just make the surface damp not
running wet. The wet & dry paper will unclog & become reusable after a
few minutes soaking in a bucket of water.When the surface is completely
sanded, (i.e. a flat finish with absolutely no shine anywhere), you can
now finish sand it with a sanding block, lots of water & the 1200 wet &
dry, a buff with a polisher & cutting polish & it's done.

Work methodically & cleanly you will soon become confident. Sorry about
all the cheese analogies.

Karen Smith.

Dwayne,

I received some Emails from others, asking what PVA is. It is a mould
release. Polyvinyl alcohol, is cheap, water soluble, sorta liquid
plastic sheet & available at your fibreglass supplier.

Gelcoat has no wax in it & stays very tacky on the surface when
exposed to air, because in a moulding situation it usually gets more
layers of fibreglass applied to it, this ensures a good bond. However in
your application this is a pain, so by applying a coat of PVA you
can exclude the air & the gelcoat will cure right through. If you get
stuck a sheet of cling wrap pressed down well achieves the same result
(is messy & will make the surface rough sometimes, more sanding:-)).

Usually it's easier to refinish the surfaces then apply any of the
spray 2 pack finishes they're strong & glossy straight from the spray gun.

Karen Smith.

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