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.

Photo of split in wooden gaff 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.

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View of split gaff with jaws removed 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.

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Photo of end view of split gaff 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.

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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.

Opening up split with a saw 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 ...

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Opening up split with a saw

... 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.

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Cleaning the widened split with sandpaper 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.

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Completed widened and cleaned split 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.

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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.

Applying unthickened Epoxy resin to the split 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.

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Injecting thickened Epoxy resin into the split 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.

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Completed repair before sanding 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.

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Completed repair with gaff jaws refitted Completed Repair

This photograph shows the completed repair with the spar varnished and the gaff jaws re-attached - all ready for use!

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Project started January 2002 and completed April 2002