Much to do With Wooden Spars | Ep. 355

Working on the hardstand during a comprehensive boatyard refit of Ruth Avery, Kevin Boothby confronted rotted wood inside the spar of his Gilmer 31 gaff-rigged cutter. Documenting the traditional woodworking procedures for How to Sail Oceans, Boothby set out to build a replacement timber insert using a bi-directional scarf joint. Rather than attempting a cosmetic surface patch, the rotted section demanded an extended timber wedge fitted flush into sound wood to restore full structural integrity to the rig.

Cutting and Bonding the Mast Scarf Joint

Constructing the mast scarf began by laying out the slope across a fresh timber block to create a long, bi-directional wedge. Boothby marked the taper lines across both sides of the wood, then used a crosscut saw to cut down to the layout marks at regular intervals. With the relief kerfs established, he took a wood chisel to knock away the wastage before truing and fairing the mating surfaces with a hand plane. Modern epoxy formulation eliminated the unforgiving joinery tolerances demanded by historic glues.

As Boothby explained while fitting the replacement timber, “Epoxy will fill the gap and the bond will be just as strong as if it was just one piece of wood.” He applied an initial wet-out across the joint using straight, unthickened epoxy, smushing it deep into the grain. To bridge irregularities without sacrificing structural strength, he blended 404 thickening compound into the resin mix. After spreading the thickened epoxy across both mating faces, he clamped the timber securely and left it for an overnight cure.

Once the epoxy cured solid, Boothby returned with his crosscut saw to saw down into the remaining exterior wastage. He cautioned against rushing the stock removal: “Don’t get too greedy. Cuz if you go too far, then you have to glue more wood back on.” He worked through multiple measured iterations, sawing and chiseling away the excess timber before switching to a bevel plane and sander to bring the scarf perfectly flush with the mast profile.

Sealing and Sheathing the Topsail Throat

Between timber operations, Boothby addressed the topsail throat hole to safeguard against internal moisture damage. He mixed penetrating epoxy further thinned with rubbing alcohol, designed to saturate deep into the raw end grain. After taping the underside of the hole to restrict drainage, he poured the thinned resin directly into the throat and allowed it to soak in slowly like sand through an hourglass, ensuring no rainwater could seep down into the timber fibers to initiate rot.

Once the penetrating epoxy saturated the wood, Boothby reinforced the opening by installing fiberglass roving inside the bore. He dripped resin into the fibers to create a composite internal sleeve. This protective fiberglass liner formed a smooth, sealed interior sheath that prevents line friction and stops standing rainwater from penetrating the wooden spar structure.

Ground Tackle Overhaul and Anchor Preparation

Taking advantage of down time during resin cures, Boothby serviced his ground tackle. He applied fresh paint to his older 44-lb Spade anchor, which serves aboard Ruth Avery as a secondary storm bower. While Boothby relies on a 44-lb Vulcan as his primary working anchor, the Spade remains a dependable heavy-weather backup despite its tendency to rust.

To upgrade the secondary rode, Boothby prepared a 10-ft length of 3/8 chain to shackle to the Spade anchor shank. The short chain leader provides sufficient weight to hold the anchor shank flat against the seabed for optimal holding power, while keeping the total weight manageable enough to row out and deploy from the rowing dinghy during rough weather.

Shaping the Topsail Yard and Jackyard

With the mast repair and ground tackle complete, Boothby turned to building a new yard and jackyard for a larger gaff topsail. He began by drilling line pass-through holes at the spar ends while the stock remained square dimensional lumber. Drilling early made measuring and locating exact spar centers far simpler than trying to center holes on rounded timber. The finished holes will secure lines passing through the head cringle, bottom luff cringle, clew, and foot.

Next came tapering each end of the spars. Because the halyard secures near the center of the topsail yard, maximum bending forces concentrate at the midpoint while stress diminishes toward the tips. As Boothby noted, “And a taper not only looks nicer, but it’s also maximally efficient in terms of weight.” He marked taper lines on the timber sides, cut relief cuts about every inch down to the layout marks with a crosscut saw, chiseled away the waste chunks, and smoothed the flats with a bevel plane.

To transform the tapered square timbers into rounds, Boothby converted the square cross-section into an eight-sided octagon resembling a stop sign. He marked lines approximately one-third in from each square edge, sawed off the four exterior corners, chiseled the waste, and planed the flats smooth. Upon roughing out the spars, he noted a slight spring in the wood: “There’s internal stresses and strains inside the timber. So, when you rip it out, it springs on you and you get a bend in it.” The rough octagons stood ready for final rounding with hand planes and sanding to eliminate all saw notches.

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