"Board-and-batten" siding is an exterior treatment of vertical boards with battens covering the seams. One method is to use furring (battens, strapping) fastened vertically to the wall. The floors were constructed using battens, rectangular in shape, above which planks were laid. The most common use of sail battens is in the roach of a mainsail. The roof peaks themselves are built up out of many small battens and rafters. Cleats attached to the battens secure the roofing pans. All ceilings are fibre-cement with battens and plaster ceiling roses. Rotational sails have "battens" which protrude beyond the back aspect of the mast. The underfloor area was sometimes decoratively screened at the perimeter with timber battens. The battens will tame the luffing sails. Historic photos show sails with as many as 10 panels and even small battens inserted. The structure is reinforced by two full length vertical battens. The full-length battens keep the sail flatter than ideal in all wind conditions. Inside, the cracks were covered with narrow wooden battens. Racing sailboats may have full-length battens, as well, that allow for better sail shape.