Practical Boat Owner - July 2018

(^6)
... but the strakes were carefully
profiled by hand to avoid taking off
too much material with the sander and
maintain their sharply angled edges.
(^3)
The worst of the damaged strakes
were reinforced with strips of
biaxial tape pressed onto the tacky
surface and then thoroughly wetted out.
5
The rest of the fairing process could
now be completed. Once the filler
had hardened it could be sanded fair,
mostly using a sanding machine...
7
The surface was closely examined and any
remaining blemishes were filled and faired
again before a final sanding with a fine sander to
make the whole hull smooth.
8
The surface
was then
coated once again
with resin/hardener
and allowed to tack
off for a couple of
hours before the
next step.
(^3)
When grinding it is important to keep the lift and spray
rails as sharp as possible to maintain the hull’s
handling performance.
4
Here’s the hole in
the side of the
damaged strake,
revealed in all its glory.
it’s very likely the
source of the leak.
5
Various other voids were revealed in
the lay-up where the resin had not
penetrated properly during original
construction, and these were scraped out
using a big screwdriver. The hull was left
to dry out for a couple of weeks.
2
After rollering, the resin was left to
become tacky (a couple of hours at
15°C). The surface was then ready to be
filled and faired.
(^4)
We used the
same resin/
hardener mix but
thickened with 407 low-density filler to the
consistency of peanut butter. This was
worked into the voids and sanding marks
with a spatula so the surface was smooth.
1
We mixed the epoxy resin (easy with
the West System – one pump stroke
of resin to one of hardener). It was stirred
until thoroughly
mixed, then applied
evenly over the entire
bottom of the boat
with a roller, taking
care to work it well
into damaged areas.
PRACTICAL
Depending on the size of vessel and
the extent of the repair it may be
necessary to leave the hull to dry
for several months and to employ
a surveyor to check the moisture
content of the hull before beginning
the repair process.
In our case the boat had spent
nearly a year in the shed awaiting
repair and was virtually ready once
we’d removed the gelcoat.
The ambient temperature ideally
needs to be above 10ºC for ease of
working. As the temperature drops
the resin becomes thicker, is harder
to mix, difficult to apply and cures far
more slowly. In borderline conditions
resin and hardener can be gently
warmed BEFORE mixing using a hot
air gun or, better still, store them
somewhere warm before use.
Drying times
Filling and fairing