Ships – Watercraft with means used in providing sailpower – Having specifically defined hull shape
Patent
1989-11-21
1992-08-04
Swinehart, Ed
Ships
Watercraft with means used in providing sailpower
Having specifically defined hull shape
114 90, B63B 3582
Patent
active
051349523
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to an improvement for a sailboard. More specifically, the present invention relates to a sailboard having mechanism actuatable by the user while under sail to adjust the downhaul tension and/or outhaul tension to achieve a desired change in the shape of the sail airfoil.
BACKGROUND ART
In known sailboard constructions a generally horizontal, aftward-extending boom is lashed to the upright mast. The head of the generally triangular fore-and-aft sail is connected to the tip of the mast such as by a pocket of the sail head being fitted over the mast tip. The clew of the sail is connected to the aft end of the boom by the outhaul. The tack of the sail is connected to the foot of the boom by the downhaul. Sometimes the connection of the head of the sail to the mast can be adjusted during rigging to accommodate masts of different heights. Prior to sailing, the outhaul tension and the downhaul tension are set. None of these adjustments is altered during sailing.
Sophisticated and expensive sailboard sails have been designed to change shape in differing wind conditions. For example, different sail materials can be used in different parts of the sail to stretch differently depending on wind direction and strength. In addition, sailboard sails have been designed to take advantage of the inevitable structural changes due to dynamic loading while sailing, such as changes in mast curvature. Still, the shape of the sail airfoil has been predetermined at the time of rigging and there is no known mechanism permitting changes while under sail.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, a first fluid pressure member is mounted inside the foot portion of the mast of a sailboard and a second fluid pressure member is mounted in the aft end portion of the boom. The first fluid pressure member is actuatable to extend or retract the mast. Since the head of the sail is fixed to the tip of the mast and the tack of the sail is connected to the foot, the result of extending the mast is to increase the downhaul tension, whereas the result of retracting the mast is to decrease the downhaul tension. The fluid pressure member can be a jack with a reciprocating plunger or an extensible bellows member connected between telescoping, relatively slidable mast portions. The second fluid pressure member preferably is anchored to the boom with a reciprocating member or portion connected directly to the outhaul to tighten or loosen it by introducing or exhausting fluid from such second fluid pressure member. Manual controls for the separate fluid pressure members are conveniently mounted on the boom for access by the user while under sail. The change in downhaul and/or outhaul tension effects a change in the shape of the sail to adapt it for changing wind conditions or runs in different directions relative to the wind.
The mechanism in accordance with the invention is compact, of simple construction and easy to use, yet reliable over a long period and easily adaptable to sailboards, sails and rigging systems of different manufacturers.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagrammatic top perspective of a sailboard having a first embodiment of downhaul tensioning mechanism in accordance with the present invention;
FIG. 2 is a fragmentary side elevation of the foot portion of the mast of the sailboard of FIG. 1, and the adjacent structure, with parts broken away, and FIG. 3 is a fragmentary top perspective of essentially the same structure with parts shown in exploded relationship;
FIG. 4 is a fragmentary top plan of the boom of the sailboard of FIG. 1 with parts broken away to illustrate other components of the first embodiment of downhaul tensioning mechanism in accordance with the present invention;
FIG. 5 is a schematic fluid circuit diagram of the first form of downhaul tensioning mechanism in accordance with the present invention;
FIG. 6 is a somewhat diagrammatic, fragmentary, side elevation of the preferred embodiment of downhaul and outhaul tension
Neil Pryde Limited
Swinehart Ed
LandOfFree
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