In a

keel The keel is the bottom-most longitudinal structural element of a watercraft, important for stability. On some sailboats, it may have a fluid dynamics, hydrodynamic and counterbalancing purpose as well. The keel laying, laying of the keel is often ...

boat, a death roll is the act of broaching to windward, putting the

spinnaker pole A spinnaker pole is a spar used in sailboats (both dinghies and yachts) to help support and control a variety of headsails, particularly the spinnaker. It is also used with other sails, such as genoas and jibs, when sailing downwind with no s ...

into the water and causing a crash-

jibe A jibe (US) or gybe (Britain) is a sailing maneuver whereby a sailing craft reaching downwind turns its stern through the wind, which then exerts its force from the opposite side of the vessel. It stands in contrast with tacking, where ...

of the boom and

mainsail A mainsail is a sail rigged on the main mast (sailing), mast of a sailing vessel. * On a square rigged vessel, it is the lowest and largest sail on the main mast. * On a fore-and-aft rigged vessel, it is the sail rigged aft of the main mast. T ...

, which sweep across the deck and plunge down into the water. The death roll often results in the destruction of the spinnaker pole and sometimes even the dismasting of the boat. Serious injury to crew is possible due to the swift and uncontrolled action of the boom and associated gear sweeping across the boat and crashing to the (now) leeward side. For

dinghy A dinghy is a type of small boat, often carried or Towing, towed by a Watercraft, larger vessel for use as a Ship's tender, tender. Utility dinghies are usually rowboats or have an outboard motor. Some are rigged for sailing but they diffe ...

sailors, a death roll is a common type of oscillation while running downwind. It may, and often will, result in a capsize and even a full inversion if the skipper does not take quick action to prevent one. During a death roll, the boat ''rolls'' from side to side, becoming gradually more unstable until either it capsizes or the skipper reacts correctly to prevent it. While on the dead run, off the wind, the force exerted by the sail lies almost parallel to the center line of the boat. There is little or no force causing the boat to heel to leeward, unlike most other points of sailing, and, if the sail is out past perpendicular to the center line, or the sail is incorrectly shaped, there may be a force causing the boat to heel to windward. Instabilities in the wind, and turbulence caused by the sail, which 'fouls' the wind on such a tack, may cause this force to change rapidly. Most sailors also retract the

centerboard A centreboard or centerboard (US) is a retractable hull appendage which pivots out of a slot in the hull of a sailboat, known as a ''centreboard trunk'' (UK) or ''centerboard case'' (US). The retractability allows the centreboard to be raised t ...

s of their dinghies while on the run, to reduce drag and increase speed. The lack of resistance to the rolling motion can enhance it. IOR (International Offshore Racing) boats in the 1970s and 1980s were known for death rolls due to their small mains that made them unbalanced downwind. Many boats put up spankers, big A-type sails set to leeward and flown away from the boat, to balance the boat. The higher the wind speed, the more important the spanker was to balance the boat.

Boats prone to death rolls

High-performance racing dinghies are most prone to death roll situations. These include skiff designs, such as the Musto Skiff, 29er, 49er and International 14. Sailors of these boats generally prefer to sail on the broad reach rather than on the dead run because the boat is more stable and actually faster. Additionally, as their speed increases on the broad reach, their

apparent wind Apparent wind is the wind experienced by a moving object. Definition of apparent wind The ''apparent wind'' is the wind experienced by an observer in motion and is the relative velocity of the wind in relation to the observer. The ''velocity ...

changes to allow them to point lower. Often they can point as low as the other boats, only faster. See '' Sailing faster than the wind''. More traditional racing dinghies such as the

Laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

and Laser Radial are also prone to death rolls. Singlehanders without shrouds will actually sail faster downwind when sailing slightly "by the lee", or past dead downwind, where stability improves and death rolls are less likely.

References

{{DEFAULTSORT:Death Roll Sailing manoeuvres