1
Initially it
appears that
gelcoat had been
painted directly on
top of the glass fibre
lay up. This produced
an irregular surface
which was now
covered by many
layers of flaking paint.4
For repairs to be effective there are
no shortcuts to preparation and after
abrading the sole it was thoroughly
cleaned. Use a solvent such as
isopropanol for this and not acetone.2
Where the paint
had worn thin it
could be seen that
there was gelcoat
crazing.5
The previous masking tape was
removed and replaced with a clean
double layer. This would save time later as
shown opposite.3
Using masking tape, the area to
be repaired was marked out and then
the old layers of paint had to come off. This
was a laborious job which required a
combination of methods (see below).
With so many layers
of paint, cleaning and
preparing the surface was
a long job. Paint removal
was carried out using an
orbital power sander, a
mini grinder and by hand
using a sanding block
with 60 grit reduction
paper. However, even the
combined force of these
didn’t achieve the results
required and none of
the abrasive techniques
managed to fully penetrate
all the grooves and small
hollows in the original
lay up.
For this it was back
to working by hand. The
most effective tool I foundfor thoroughly cleaning
the most irregular areas
of the glass mat surface
was a Bahco 625 scraper
fitted with a pear carbide
blade. For the finest work
up against edges etc
the end with the smaller
radius was ideal; for the
rest of the time I used the
larger round end. It was a
slow method but the only
one I found to achieve the
level of clean up required
for successful bonding of
the cloth. Working by hand
also caused a lot less dust
than the other methods
and did not reduce the
thickness of the laminate
more than necessary.PREPARATION
CLEANING UP
PRACTICAL
remedy is to grind out the defects which
can then be repaired with either more
gelcoat or marine filler. However, even on
small areas this is a very dusty job and with
a small grinder it can be hard to rig up an
effective dust extraction system.
Alternatively for small sections you can
‘vee’ the cracks with the corner of a sharp
chisel and this provides enough of a key
for the repair material.
But with a large area like the interior of the
tender, the numerous local repairs required
would have been impractical. I also thought
that the amount of grinding back needed to
carry this out could have further weakened
the thin laminate of the dinghy. My
preferred option was to provide a new
internal hull skin altogether. To achieve this
required the existing sole to be thoroughly
abraded, and I could then sheath the whole
lower interior with a new layer of woven
glass cloth and epoxy. This would both
solve the problem of the damage and
provide a strong, rigid new sole to the
dinghy. Here’s how I did it and the same
principles outlined below can also be used
on other areas of laminate which also
require strengthening.