Tacking, gybing and heaving to

The lesson in plain words

1. What happens
   • An accidental gybe happens when the wind gets behind the mainsail from the wrong side and throws the boom across without anyone choosing it.
   • The boom can hit a head with enough force to cause serious injury or knock someone overboard.
   • The mainsheet sweeps the cockpit, and the shock can break the boom, the gooseneck (its fitting on the mast) or the rig.
2. Sailing by the lee
   • On a run, wind coming from the boom side means you are sailing by the lee.
   • A wave, wind shift or steering error can throw the boom across.
   • Check the apparent-wind indicator.
   • A lifting or fluttering leech, the mainsail's back edge, is another warning.
   • A collapsing headsail may simply be blanketed by the main: check wind direction.
3. Steering to prevent it
   • Keep the apparent wind clearly on the side opposite the boom.
   • Allow for yaw, the boat swinging from side to side, and wind shifts.
   • Concentrate on steering; make small corrections early and watch the wind indicator.
   • Head farther up onto a broad reach, with the wind over your rear quarter, if waves push you towards a gybe.
4. The preventer
   • A preventer is a line that holds the boom out so it cannot swing across.
   • Rig it from the outer end of the boom, forward to a strong point or block near the bow, and back to the cockpit.
   • Use strong fittings and a cockpit release that works under load.
   • A line from mid-boom straight down to the rail can break the boom if the boat rolls the boom into the sea.
5. Boom brake and crew
   • A boom brake is a friction device that lets the boom cross slowly instead of stopping it.
   • It is an alternative to a preventer and is useful when sailing short-handed.
   • Whatever you rig, keep everyone's head below the boom on a run, and never sit or stand in the mainsheet's path.
   • Control the boom with the mainsheet before easing the preventer for a gybe; rig it again on the new side.

Key data

Key points

• An accidental gybe can injure crew and break the boom or rig.
• Danger zone: sailing by the lee, wind on the boom side on a run.
• Watch wind direction and the mainsail leech; a collapsing headsail alone does not prove you are by the lee.
• Rig a preventer from the boom end forward and back to the cockpit.
• Keep heads low; control the boom with the mainsheet before easing the preventer for a gybe.

Check what you have read

True or false?

Practice case & exam keys

Exam keys

1. 1Accidental gybe: boom crosses uncontrolled; serious injury and rig damage.
2. 2By the lee: wind from the boom side. Check wind direction; headsail collapse alone is not proof.
3. 3Preventer: boom end, forward, back to cockpit; use a release that works under load.
4. 4Keep wind clearly opposite the boom; allow for yaw and shifts. Control boom before easing preventer.