Woodworking Tip of the Day: Fairing Battens

Not for nuthin'…. But….. a fair curve isn't what your eyes hope for — it's what a good batten will agree to. Today's tip: fairing battens — picking stock that bends honest, spotting bumps and hollows, and fixing them before you cut good cedar.

Why it matters: Yesterday we spiled the plank shape off the boat. Today you connect those points (or fair a sheer, a mold edge, a ribband) with a batten. On a Chamberlain Marblehead gunning dory, that fair line is the difference between a plank that lands sweet and one that fights every clamp. WoodenBoat (Bud McIntosh's lofting chapter) and Robert M. Steward both hammer the same truth: the batten finds fairness — you don't invent it with a French curve and wishful thinking.

Materials

• Fairing / lofting battens — clear, straight-grained, knot-free stock (clear white pine is the classic pleasant choice; straight-grained oak or ash when you need something very limber)
• A small quiver of sizes — stiffer for long gentle lines, thinner for tight stem / body-plan curves
• Colored chalk (blue carpenter's chalk works) for marking highs
• Fivepenny nails (or similar) to set as fence posts against the batten — not through it
• Optional: spare thin strips to shim a persistent low

Tools

• Pencil and a sharp eye (get your sight line parallel to the surface)
• Handplane / block plane for taking downs highs on wood you're shaping
• A light behind the batten edge (shop lamp, bright wall, or cardboard)
• Longboard or sanding stick when you're into fairing compound / finish fairing

Steps

1. Pick honest stock. Clear, straight grain, no knots, no wild swirl. A knot is a hard spot that kinks the curve and then snaps with no warning (every amateur boatbuilder learns this the expensive way). Steal battens from clear ribband / stock when you can, and hang them where feet and kids can't find them (WoodenBoat).
2. Match stiffness to the curve. Steward's rule, echoed all over the shops: start with the stiffest, largest batten that will still bend around the curve, then rip narrower if you must. A floppy batten will follow every mistake; a too-stiff one will break or refuse the turn. Long sheer lines want more backbone; tight stem and body-plan curves want limber stock (oak/ash under ⅜″ square in McIntosh's lofting kit — that's his example, not a universal cut list).
3. Set the fence posts. Drive nails at your known points (offsets, stations, spiling intersections). Pull the batten in against that row of posts. Hold it with nails driven against the batten, not through it, so you can ease it in or out (WoodenBoat).
4. Read unfairness. Sight along the batten with light behind the edge. A bump / high lifts the batten or takes chalk when you rub a chalked batten across the surface. A hollow / low shows as a gap under the edge (WoodenBoat fairing practice; Gougeon / Epoxyworks chalk-stick method). On lofting, the unfair station is the nail the batten refuses — move that nail, don't force the stick into a kink.
5. Correct, then re-check. Ease highs (plane / sand the high wood, or move the high nail toward the fair line). Fill or shim persistent lows — don't chase a hollow by digging the neighbors deeper. Iterate lightly overall; rushing one section is how you get a potato-chip fair. Done when a critical eye and the batten agree — ideally the batten touches everywhere without showing unfair bends (WoodenBoat).
6. Mark and move on. Once the batten lies fair, mark the line, pull the batten, and protect that stick like shop gold. Same battens serve lofting, ribband fairing, and connecting spiling points on the bench.

MOAM's shop note: Biggest miss is "helping" a stubborn station by shoving the batten into a kink so every nail looks touched — you've just drawn a lie into the plank. Second miss: a knotty scrap you swore was "good enough." Third: sanding a low spot instead of filling it, which digs the hollow deeper while the highs laugh at you. Keep a quiver. Start stiff. Trust the batten more than your optimism. That's how the Marblehead dory's curves stay honest from loft floor to last plank.

MOAM Out.