Source: {"pile_set_name": "USPTO Backgrounds"}

A number of devices have been available for locking or stabilizing the position of a boom of a sail boat when sailing with a following or quartering breeze. The importance of some control will be recognized by those skilled in the art who have experienced the effects of an accidental jibe due to a shift in wind direction or when the helmsman accidently changes course so that the wind is on the opposite side of the main sail and the boom suddenly swings across the deck. Such accidental jibes are hazardous to the crew, can cause serious damage to the rigging and may even cause a knockdown of the vessel. Even controlled jibes can be hazardous if not done with care.
Short of lashing the boom or through use of a preventer or similar boom locking device, a number of sail boat boom brakes utilizing the frictional resistance applied by a friction device to a line which restrains movement of a boom have become available and are a part of the prior art. One of these systems known as the Heinson boom control system produced by the Heinson Co., Moraga, Calif. works on the principle disclosed in U.S. Pat. No. 4,138,962. In this type of system, a friction device in the form of a single friction drum is carried by a hanger attached to the boom of the boat. A line attached to one or more cleats accessible from the cockpit extends forwardly to a swivel block mounted on the deck. The line extends from the swivel block to the drum, is wrapped around the drum several times and then extends downwardly to a second cleat or another swivel block on the opposite side of the boat from which it is extended aft to a second cleat accessible from the cockpit. When the line is cleated, frictional resistance with the drum locks the boom in place. Tension may be released from the cockpit entirely or may be gradually released as a jibe occurs, thereby easing the boom to the desired position.
More recently issued U.S. Pat. No. 5,390,617 illustrates another type of boom brake mounted on a hanger attached to the boom. In this patent, the hanger carries three spools or sheaves. A line secured adjacent one side of the deck extends to the boom and in a serpentine path is in contact with the friction surfaces of the three spools. Two of the spools are fixed against rotation and the third, offset between the first two, is rotatable and is provided with a manually adjustable brake so that a variable frictional resistance to motion can be applied. In a further embodiment of the patent, where adjustable braking is not required, the three spools are all non-rotatable.
Many sailors object to devices of the kind described due to the fact that they are relatively difficult to control by the helmsman while he is in the act of steering the boat and also because the relatively heavy braking device is located where it can strike the head of a crew member, creating the kind of hazard that such devices are intended to eliminate.