Ships – Sail or control means therefor – Reefing and furling
Reexamination Certificate
2000-09-19
2001-11-20
Sotelo, Jesus D. (Department: 3617)
Ships
Sail or control means therefor
Reefing and furling
C114S108000
Reexamination Certificate
active
06318285
ABSTRACT:
FIELD OF THE INVENTION
The present invention is related to furling systems for attaching to sails on sailing vessels. In particular, the present invention is related to furling systems used to rotatably attach to a furling sail.
BACKGROUND OF THE INVENTION
Furling sails are known in the art. They are generally a jib that may be wrapped about a stay for storage when not in use. The wrapping of the furling sail allows the sail to be easily stored and deployed. As illustrated in
FIG. 1
, a furling sail
6
is typically attached at its base to furling drum
4
, which may be wound and unwound using an attached rope
8
to deploy and retract sail
6
(illustrated as partially unwound). The head of the furling sail is attached to a support such as the sailboat masthead
10
using swivel
2
, while the tack of the sail is attached to the rotating furling drum
4
. The swivel
2
and drum are connected to one another by foil
12
, which rotatably rides over a headstay. The swivel
2
generally has a top body element that is attached to the masthead, and a lower body element attached to the furling sail head and that rotates with the drum
4
as the furling sail is wound and unwound around the foil
12
.
Further detail regarding furling systems and furling swivels of the prior art is available in the 1999 products catalogue of Harken Inc., Pewuakee Wis., USA; incorporated herein by reference. In particular, attention is drawn to furling systems comprising drums and swivels illustrated on pages 115-129 of the catalogue.
A number of heretofore unresolved problems exist with furling systems. The furling sail swivel and drum must anchor a sail that may be under very heavy wind loads. Additionally, the swivel and drum must withstand severe weather conditions. With these considerations in mind, furling swivels and drums are generally of relatively robust and heavy construction. The swivel and drum typically have an extended tang with an eyelet through which a stainless steel linkage piece such as a clasp or bracket connects to the sail. The relatively heavy construction of the tang and brackets used to attach the sail head and tack are disadvantageous for sailing vessels, as there is a desire to keep weight to a minimum. Further, the swivel is located at the top of the furling sail high up in the rigging of a sailing vessel. This compounds the effects of its relatively heavy weight, as weight high aloft is particularly disadvantageous because it increases heeling of the boat.
The clasps or brackets used to attach the sail head and tack may disadvantageously deform or even fail through fatigue. This results from the stresses sails are under in combination with the extreme weather conditions the clasps or brackets are exposed to.
An additional unresolved problem with furling sail swivels and drums relates to their wind drag characteristics. It is desirable for sailing vessels to have minimal wind drag, particularly aloft. The extended tang on the furling system drum and swivel result in disadvantageous wind drag characteristics.
The tang and bracket used to attach the sail to the swivel and to the drum are also disadvantageous for reasons in addition to weight and wind drag. In particular, the length of the tang increases the bending moment on the swivel and drum. Also, the tang concentrates the bending stress on a small portion of the swivel or drum. As the drum or swivel rotates, this increased and concentrated bending moment is passed on to a small portion of the bearings or other rotation facilitating means used by the drum or swivel. This disadvantageously increases frictional resistance to rotation of the drum or swivel, as well as decreasing the service life of the bearings.
An unresolved need therefore exists for an improved furling sail system.
OBJECTS OF THE INVENTION
It is an object of the present invention to provide a furling sail system of lightweight construction.
It is a further object of the invention to provide a furling sail system having an advantageous wind drag profile.
It is a further object of the invention to provide a furling sail system having a minimal bending moment on rotating bearing means.
It is a further object of the present invention to provide a method for attaching a furling sail to a furling system.
SUMMARY OF THE INVENTION
The furling sail system of the present invention generally comprises at least one rotating member for attachment to a sail, the rotating member having a perimeter, with the rotating member further having cordage attachment means for guiding a length of cordage about at least a portion of the perimeter of the rotating member, the cordage for attaching a sail. Preferably, the cordage attachment means comprise at least one channel through which the length of cordage may be passed. More preferably, the attachment means comprise a pair of channels. The pair of channels cooperate with one another whereby the rope may be passed from one channel, over a portion of the rotating member perimeter, and through the other of the pair of channels. Preferably, the cordage attachment means guide the length of cordage about at least 40% of the rotating member perimeter.
In a first embodiment of the invention, the at least one rotating member of the furling system comprises a furling sail swivel for attachment to the head of a furling sail, with the swivel generally comprising a top body element, a bottom body element having a perimeter, the bottom body element rotatably connected to the top body element; and cordage attachment means on the bottom body element, the attachment means for guiding a length of cordage about a portion of the bottom body element perimeter.
In a second embodiment of the furling system of the invention, the rotating member comprises a rotating drum for attachment to a furling sail tack, the drum generally comprising a spool and a body, the body having cordage attachment means for guiding a length of cordage about at least a portion of the body.
In a most preferred embodiment of the furling sail system of the invention, the system comprises at least two rotating members: a rotating drum for attachment to a sail tack, and a rotating swivel for attachment to a sail head, each having cordage attachment means for guiding a length of cordage about at least a portion of the perimeter of the respective swivel or drum. In particular, this most preferred embodiment comprises a furling swivel for attachment to the furling sail head, the swivel having a top body element, a bottom body element rotatably connected to the top body element, the bottom body element having a perimeter, and having first cordage attachment means on the bottom body element for guiding a first length of cordage about a portion of the bottom body element. The preferred furling sail system further comprises a furling drum for attachment to the furling sail tack, the furling drum having a spool and a body connected thereto, the body having a perimeter, second cordage attachment means on the drum body, the second cordage attachment means for guiding the second length of cordage about a portion of the drum body perimeter. The drum and swivel may be connected to one another by the furling sail. The drum and swivel may also be connected by a foil that rotatably runs over a headstay.
The furling sail system of the present invention in its all of its various to embodiments solves all of the aforementioned problems in the prior art. In particular, the novel cordage attachment means allow for attachment of a sail without use of a tang, shackle, bracket, or other additional means. This substantially lowers the weight and dramatically improves the wind drag profile of the rotating member. Additionally, problems associated with bracket or clasp fatigue and failure are eliminated.
The furling sail system of the present invention also solves problems of the prior art related to load placed on rotating member bearing means. Because the sail is attached to the rotating member of the invention by guiding a length of cordage about a portion of the circumference of the member, the load is
Hartlmeier Greg
Omohundro Thomas
Harken, Inc.
Pyle & Piontek
Sotelo Jesus D.
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