SKETCHBOOK

Dealing with large mainsail roaches

A In the early days of cruising, some skippers preferred a straight leech that did away with the chafe and bother of battens. The leech would even sometimes be cut concave to prevent it hooking back on itself. Extra area could then be added by having a “bumkin” aft to keep the backstay clear.

B The roach is the bit of curved sail sticking out beyond a straight line drawn from the head to the clew. Battens in pockets stop it flopping about, and the resulting extra sail area was eventually allowed within some racing rules.

C Aerodynamic research created beautifully efficient aircraft wings, which prompted sail designers to experiment with similarly curved trailing edges. Multihulls and windsurfers can have massive roaches because there’s no backstay to constrain them. With a backstay, modest roaches are typical. However, many modern rigs now have horizontal fully-battened mainsails with roaches that overlap the backstay—and in light airs, the top battens can snag the backstay.

D If you have a modest rig and find your top battens snagging while tacking in light winds, you could try changing the battens for shorter ones or ones made of a more flexible material that will slip past the stay more easily.

E If the gooseneck is on a track, just lower the lot down. If, on the other hand, it’s fixed, having a shallow flattening reef sewn in might be cheaper than having the leech recut. I sailed on one boat with a small reef that improved the slightly saggy old sail shape so much the skipper kept the sail for several more years.

F Extending the masthead crane aft can lift the backstay off the leech, but take care, as it might affect the way the mast bends.

G A flicker, or mast whip, is used on some modern boats to lift the slack backstay away from their generously curved leech roaches.

H Some sailmakers fit slippery antichafe patches at the ends of the battens and claim they last for ages.

I Racing sailors are always fiddling with their control lines and reckon they can either dip the boom during the tack or slacken the backstay and flip it past the battens.