Battens have plenty of other uses besides battening down hatches. Some specialized types of battens are invaluable tools in wooden boat construction
A fairing batten (usually called just a "batten") is used for drawing fair curves (i.e. splines) on your lofting board, or on the wood you're working. You, the shipbuilder, will:
- Make a series of pencil marks on the work surface based upon a series of other measurements.
- Nail the batten into work surface so that one edge of the batten is right up against every mark. As you might guess, a nail for each mark is most practical. The natural springiness of the wood does most of the work.
- Eyeball the curve produced by the nailed-in batten. If it's not fair, you'll know it; you'll see bumps or valleys around particular nails. Those nails get knocked out and nailed back in in a better place. Sometimes you can simply tap the nail on the side.
- Draw the line, when the you're satisfied with the fairness of the curve.
- Pull up the nails, put the batten aside, and go on the the next curve.
You need a more-or-less square strip of clear pine or fir as long as the boat. The grain has to be even so that the strip will bend evenly. The thickness of the batten depends upon how gentle you want your curves to be: the thicker the batten, the less it likes to bend, the more it likes to spring back, and the more gentle the curve will be. For a particularly twisty curve you need a thin (1cmx1cm), light, floppy batten; for a 30-meter-plus ship you might need a 33-meter long batten, 5cmx5cm, made of oak. As you might guess from the state of the world's forests, good battens are hard to come by, so treat yours with respect. Of course, don't be afraid to put a nail through one if you need to!
A spiling batten, a wide, flat piece of scrap wood used during "spiling", measuring for points along the edge of a strake (side plank) of the boat. A spiling batten has to be flexible enough to drape across the roundness of the boat, but shouldn't bend in the direction you're measuring the points. A spiling batten needs to be about 1/2 meter longer than the strake you're about to carve. You can glue one up if you don't have a piece long enough.