Death roll
Encyclopedia
In a keel
boat, a death roll is the act of broach
ing to windward, putting the spinnaker
pole into the water and causing a crash-gybe
of the boom and mainsail, which sweep across the deck and plunge down into the water. The Death Roll often results in destruction of the spinnaker pole and sometimes even demasting 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
sailors, a death roll is a common type of oscillation while running downwind. It may, and often will, result in a capsize
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 centerboards of their dinghies while on the run, to reduce drag and increase speed. The lack of resistance to the rolling motion can enhance it.
These include Skiff designs, such as the Musto Performance Skiff, 29er
, 49er
and International 14
. Sailors of these boats generally prefer to sail on the broad reach 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
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
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 deathrolls are less likely.
Keel
In boats and ships, keel can refer to either of two parts: a structural element, or a hydrodynamic element. These parts overlap. As the laying down of the keel is the initial step in construction of a ship, in British and American shipbuilding traditions the construction is dated from this event...
boat, a death roll is the act of broach
Broach (sailing)
A sailboat broaches when its heading suddenly changes towards the wind due to wind/sail interactions for which the rudder cannot compensate. This causes the boat to roll dangerously and if not controlled may lead to a capsize...
ing to windward, putting the spinnaker
Spinnaker
A spinnaker is a special type of sail that is designed specifically for sailing off the wind from a reaching course to a downwind, i.e. with the wind 90°–180° off the bow. The spinnaker fills with wind and balloons out in front of the boat when it is deployed, called flying. It is constructed of...
pole into the water and causing a crash-gybe
Jibe
A jibe or gybe is a sailing maneuver where a sailing vessel turns its stern through the wind, such that the wind direction changes from one side of the boat to the other...
of the boom and mainsail, which sweep across the deck and plunge down into the water. The Death Roll often results in destruction of the spinnaker pole and sometimes even demasting 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
Dinghy
A dinghy is a type of small boat, often carried or towed for use as a ship's boat by a larger vessel. It is a loanword from either Bengali or Urdu. The term can also refer to small racing yachts or recreational open sailing boats. Utility dinghies are usually rowboats or have an outboard motor,...
sailors, a death roll is a common type of oscillation while running downwind. It may, and often will, result in a capsize
Capsize
Capsizing is an act of tipping over a boat or ship to disable it. The act of reversing a capsized vessel is called righting.If a capsized vessel has sufficient flotation to prevent sinking, it may recover on its own if the stability is such that it is not stable inverted...
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 centerboards of their dinghies while on the run, to reduce drag and increase speed. The lack of resistance to the rolling motion can enhance it.
Boats prone to death rolls
High performance racing dinghies are most prone to death roll situations.These include Skiff designs, such as the Musto Performance Skiff, 29er
29er
The 29er is a two-man high performance skiff designed by Julian Bethwaite and first produced in 1998.-Background:It is targeted at youth, especially those training to sail the larger 49er. It has a single trapeze and a fractional asymmetric spinnaker. The Class is a more modern replacement to...
, 49er
49er (dinghy)
The 49er is a double handed twin trapeze skiff type sailing dinghy. The two crew work on different roles with the helm making many tactical decisions, as well as steering, and the crew doing most of the sail control. The design, by Julian Bethwaite, the son of Frank Bethwaite , is revolutionary...
and International 14
International 14
The International 14 is 14-foot double-handed racing dinghy. The class originated in England in the early part of the 20th century. It is sailed and raced in many countries around the world and was one of the very first true international racing dinghy classes recognised by International Sailing...
. Sailors of these boats generally prefer to sail on the broad reach 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
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....
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
Sailing faster than the wind
Devices that are powered by sails can sail faster than the wind. Such devices cannot do this when sailing dead downwind using simple square sails that are set perpendicular to the wind, but they can achieve speeds greater than wind speed by setting sails at an angle to the wind and by using the...
.
More traditional racing dinghies such as the Laser
Laser (dinghy)
The International Laser Class sailboat, also called Laser Standard and the Laser One is a popular one-design class of small sailing dinghy. According the Laser Class Rules the boat may be sailed by either one or two people, though it is rarely sailed by two. The design, by Bruce Kirby, emphasizes...
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 deathrolls are less likely.