Wooden Boat Restoration Repair - WEST SYSTEM Epoxy

4. Push the wet-out spline into the seam (Figure 5-4). The taper on the spline should force
epoxy to the sides, making good contact with the spline and edges of the planks. The
spline should fit snugly in the seam with hand pressure after a small amount of epoxy
squeezes out of the joint. Staple the spline if necessary to hold it in position.
5. Clean up excess epoxy. Use a sharpened mixing stick to scrape up excess epoxy before
it cures. Station a helper inside the boat or check the inside frequently to clean any
epoxy leaking through the planking.
6. After the epoxy cures thoroughly, remove the excess portion of the spline with a plane
followed by coarse sandpaper (Figure 5-5). Fill the vertical seams and any remaining
voids with epoxy/407 fairing compound before final fairing and finishing.
7. Important! Coat the exterior following the procedures in Section 7. Failure to apply an
epoxy moisture barrier may cause structural damage when planks swell. Fiberglass
cloth is often applied to provide additional reinforcing and abrasion resistance.
5.1.3 Filling the seams with epoxy.
A quicker but more expensive way of bonding the seams is to fill the entire gap with
thickened epoxy (epoxy is more expensive than wood by volume). This method is
more practical on seams that are too curved or tight for a spline.
1. Open the seam as before. The gaps do not have to be a particular width, as long as you
expose fresh wood on each plank edge.
2. Wet out the gap with resin/hardener mixture.
3. Fill the seam with thickened epoxy/403 (mayonnaise consistency). (Note: 403 filler
will leave an off-white colored seam, which will not matter if you plan to paint the
surface. If you plan a clear finish you may want to use 405 Filleting Blend or a coloring
agent mixed with the epoxy to match the planking color. See Section 7 for information
on finishing.) Large syringes or caulking tubes are convenient to inject the thickened
epoxy into the seams. Smooth the mixture flush with the surface and remove excess
epoxy before it cures. Check the inside for leaks and clean any excess epoxy before it
cures.
4. Sand the surface fair after the epoxy cures thoroughly. Fill any remaining low areas
with epoxy/low-density filler mixture.
5. Coat the exterior following the procedures in Section 7.
5.1.4 Repairing damaged planks in place
Repairing Hull and Deck Planking 30
If you will be repairing or replacing a lot of planks, it is best to repair individual planks
and small areas completely before going on to other areas. The hull may be seriously
weakened and lose its shape if you remove too many planks at one time. Scarf joints or
butt joints can be used in repairing damaged sections of planks without removing the
entire plank. Support the hull in its proper shape before bonding.
Scarf joint method
To repair damaged sections of planks using scarf joints:
1. Remove the damaged part of the plank using a circular saw, hand saw or chisel.
2. Bevel each end of the plank opening with an 8-to-1 scarf.
3. Cut a piece of wood to fit the opening. Match the 8-to-1 bevel on each end (Figure 5-6).
Make the new piece of wood slightly thicker than the original planking. Excess
material inside or outside the hull can be planed off after the glue has cured.
4. Wet out the mating surfaces with resin/hardener mixture. Re-coat the scarfed surfaces
as necessary until the end grain is fully saturated.
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