Ships – Sail or control means therefor – Reefing and furling
Patent
1996-02-23
1997-06-24
Avila, Stephen
Ships
Sail or control means therefor
Reefing and furling
114107, B03H 904
Patent
active
056409192
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a boom for a sailing boat that includes:
an elongate structure which bounds a cavity extending in longitudinal direction;
a slotted hole extending on the top side thereof in longitudinal direction; and
a pulling member drivable by first drive means and extending in the cavity in longitudinal direction for pulling through the slotted hole into the cavity and storing therein a part of the sail to be rendered inoperative.
When sailing takes place with a known boom, the sail exerts a force on the edges of the slotted hole such that these edges tend to move apart. The open boom-structure is hereby placed under relatively heavy strain of bending in its transverse plane.
It is an object of the invention to reduce this strain.
SUMMARY OF THE INVENTION
In this respect the invention provides a boom of the type stated in the background which has the feature that the slotted hole is bounded by two mutually parallel prismatic edges with which a carriage movable therealong co-acts such that the carriage prevents a relative displacement of these edges away from each other, which carriage is movable at least partly by second drive means.
In a particular embodiment the boom according to the invention has the feature that the carriage is slidable. The carriage can also be rollable. The carriage can engage round the said edges or the edges can engage round the carriage.
The carriage has a number of functions. A first function is to tension and hold tensioned the foot when the sail is reefed out. In addition the carriage can effectively hold together the said edges in diverse reefing positions, while in reefed and non-reefed situation the carriage can be used for stretching the foot. The swing tension in the reefed situation can be fixed at a predetermined value.
A particular embodiment has the special feature that the first drive means includes at least one element which extends in lengthwise direction, is rotatably drivable round its longitudinal axis and which is coupled to the sail for exerting on that sail during operation of the drive means a tensile force for displacing the sail through the slotted hole to the cavity.
It will be apparent that the drive means must be able to exert a sufficiently large tensile force on the sail to overcome the opposing force or forces exerted by this sail, particularly when there is some wind load.
A specific embodiment has the feature that the element is a winding shaft extending in longitudinal direction in the cavity.
The boom according to the invention preferably has the special feature that in any operating position of the sail the carriage assumes relative to the boom a position which in any reefed situation is located closer to the mast than in non-reefed situation.
The embodiment is recommended which has the special feature that the second drive means includes at least one cable which is connected to the carriage and on which a tensile force can be exerted by a motor. A tensile force directed away from the mast can be of particular importance for tensioning and holding tensioned the foot.
In preference the boom is provided with a carriage which can be fixed relative to the boom by blocking means.
The carriage can be provided for this purpose with manually operated blocking means, while in the above described embodiment the fixing can consist of the fact that the motor is of the self-braking type.
The boom can be manufactured of any suitable construction material or composition thereof, for instance aluminium. In the case where the boom has a prismatic shape, that is, a shape in which the cross section is identical everywhere along the whole length, the boom can be embodied as extrusion profile. The boom can also be embodied in a fibre-reinforced plastic, a sandwich structure or other structure of sufficient strength. Particularly fibres with tensile strength such as carbon fibres, glass fibres, aramide and the like are very suitable for reinforcing purposes.
Particularly in the case where the boom-structure consists substan
REFERENCES:
patent: 4116152 (1978-09-01), Larsson
patent: 4679520 (1987-07-01), Harken
patent: 5181477 (1993-01-01), Harken et al.
Avila Stephen
Rondal B.V.
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