Repair and Maintenance of a Drascombe Lugger
Repairing a Split Spar
This page describes a method for repairing a split on one
of the Columbian Pine spars. The process consists of
widening the split so that filler-adhesive can be
injected into it. This will both seal the split and bond
the wood on each side preventing the split from widening
and extending along the spar when it is in use and under
stress.
Defining the Problem
On Sospiri There was a serious split on the gaff.
The following photographs show the extent of this and how
it was repaired.
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Split in the Gaff
Inspection of the gaff showed a long split had
developed from beneath the galvanised base of the
jaws and extending along the spar for a distance of
220 mm.
(Click on image for larger view)
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No
prizes for guessing how this split was caused...!
Removal of the gaff jaws showed more of the split.
This has obviously been caused by the screw
securing the galvanised base of the gaff jaws being
driven into the wood without a pilot hole (or too
small a pilot hole) having been drilled into the
wood first. The pressure of the screw forced into
the wood has acted like a wedge causing it to
fracture along the grain.
(Click on image for larger view)
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End view of gaff
Inspection of the end of the gaff shows that the
split is a deep one extending almost completely
across the full width of the wood.
(Click on image for larger view)
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What will happen if the split is untreated?
If left unattended water will penetrate into the split
and rot the surrounding wood. This will in turn weaken
the wood so that when the spar is stressed the split will
widen and extend further along the spar.
What are the treatment options?
The only option is to open up the split exposing fresh
wood and enabling an adhesive-filler to be injected in to
seal it and prevent it from extending. The following
photographs illustrate the treatment.
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Opening up the split
This looks horrific - as if the spar is being
sliced in two, but using a wood saw is a good way
of opening up a split. The saw can be used in this
position ...
(Click on image for larger view)
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... or in this position. If the split is in the
middle of the spar then it will not be possible to
use a saw and either a craft-knife or a scalpel
should be used to open up the split.
(Click on image for larger view)
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Cleaning the enlarged split
After widening the split it should be abraded with
a piece of 60 or 80 grade aluminium oxide abrasive
paper folded in half and used as shown here. This
removes any polishing of the wood by the metal of
the saw rubbing against the sides of the split.
Polished wood will not bond properly to the
filler-adhesive.
(Click on image for larger view)
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Completed widened and cleaned split
This photograph shows the split after widening and
cleaning. After wiping with White Spirit to
clean and degrease the wood, the split is ready for
the injection of filler-adhesive.
(Click on image for larger view)
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Filling the split
West Epoxy Resin and Filler powder 404 were used to fill
the split. The split was filled in two stages. The first
stage consisted of mixing up 15 ml of West Epoxy Resin
with 3 ml of hardner in a plastic drinking cup. A small
paint brush was used to apply this to the split. The
unthickened resin soaks into the wood more readily than
the thickened mixture. However it cannot be used to fill
the split completely as it will run out. Filler is needed
to thicken it so that it will not run out and also to
increase the bonding strength.
The second stage consisted of stirring 404 Filler Powder
into the remaining resin until it was of a similar
consistency to mayonnaise. This was then transferred to a
small disposable syringe and carefully injected into the
split so that it was completely filled. After curing (24
hours) it was sanded smooth. The process is illustrated
in the following photographs.
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Coating with unthickened Epoxy
After mixing the Epoxy Resin with the correct
amount of hardner, the resin was painted into the
split so that the wood was thoroughly wetted out.
(Click on image for larger view)
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Injecting with thickened Epoxy plus filler
Working quickly, before the remaining resin in the
cup had started to cure, some West 404 Filler
Powder was stirred in until it had reached the
consistency of mayonnaise. A small 25 ml disposable
syringe had previously been prepared by carefully
cutting the top off (using a scalpel or craft
knife) so that the plunger could be completely
removed. Some thickened Epoxy was then pushed into
the syringe using some round dowelling. The plunger
was then replaced and the syringe was used to
inject the thickened Epoxy into the crack until it
was completely filled. This is a messy process but
extremely effective.
This sandwich method in which the central thickened
Epoxy is enclosed between wood soaked with
unthickened Epoxy ensures an immensely strong bond.
(Click on image for larger view)
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Repaired split before final sanding
This photograph shows the split after the injected
Epoxy had cured. The next stage is final sanding
and re-attachment of the gaff jaws.
(Click on image for larger view)
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Completed Repair
This photograph shows the completed repair with the
spar varnished and the gaff jaws re-attached - all
ready for use!
(Click on image for larger view)
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Project started January 2002 and completed April
2002