1
Now we could
begin sheathing
the hull with glass
cloth. The biaxial
cloth used is made
up of the same thread
as standard woven
roving glass cloth,
the difference being
the way it is woven
diagonally to allow it
to drape itself easily
over complex
contours. The first
piece of cloth was
laid halfway across the width of the hull at the
stern and rolled onto the tacky surface to hold it
in position.
3
The position of
the line can now
be marked and
masking tape applied
along the actual line.
On a hull shape like
this, with many
strakes, the line seems
to run in all directions
to maintain a straight
course when viewed
from the side.
(^4)
Now we can apply antifouling – in this case Copperbot
2000 which should last for 10 years and require little
maintenance. It comes in
pre-measured packs of resin
and hardener plus a bag of
pure copper powder. These
are mixed in equal amounts
and then rolled on, following
the instructions.
(^2)
But first we had
to mark a
waterline around the
boat. This method
doesn’t require the
boat to be perfectly
level, or indeed the
right way up, as is
the case with the
water hose method.
The first stage is to
block up a tube or timber across the bow perpendicular to the fore-and-aft line with the
top edge level with the position of the waterline at the bow. A string can then be taken
from the waterline aft over the top of the timber at the bow to give a straight line. But you
can’t simply pull the string tight against the hull as it just rides up or down on the slope.
The technique is to draw the string along the timber towards the hull until it comes into
contact a couple of inches from the transom. Tape it lightly into position at that point.
Repeat the process until the string is taped to the hull throughout its length. This way it
should follow the curve of the hull and still be perfectly straight.
1
The edge of the mat was trimmed
along the waterline with a sharp
knife before the mix finally cured. The
bottom was filled, faired and sanded for
the last time, ready for antifouling.
2
The awkward
shape of the
hull and strakes
at the transom
meant some
cutting was
required to allow
the cloth to lay
smoothly on the
hull surface.
(^3)
The cloth was then rolled with epoxy
until it was thoroughly wetted out.
The same procedure was repeated to
sheath the rest of the hull, slightly
overlapping each previous layer as we
moved forward.
EPOXY SHEATH A HULL
The process shown here is identical
to that for osmosis repair. Where
there is no need for strengthening
the hull or repairing damage the
sheathing with biaxial fabric can
be omitted and, instead, six coats
of epoxy applied. However, where
damage has occurred the
process is exactly the same
with the addition of further
coats of epoxy.
Working on a smooth hull
with no strakes or rails is
far quicker and simpler than
the fairly complex example
we’ve demonstrated here.
This little runabout was
subsequently relaunched
and has proved to be totally
watertight since – a very
satisfactory result.
Good job done!
Sheathing the hull
Marking the waterline