U.S. patent application number 13/748254 was filed with the patent office on 2014-04-17 for structural support scheme for the replacement of trailing portions of sails.
The applicant listed for this patent is Malcolm L. Gefter. Invention is credited to Malcolm L. Gefter.
Application Number | 20140102346 13/748254 |
Document ID | / |
Family ID | 50474200 |
Filed Date | 2014-04-17 |
United States Patent
Application |
20140102346 |
Kind Code |
A1 |
Gefter; Malcolm L. |
April 17, 2014 |
Structural Support Scheme for the Replacement of Trailing Portions
of Sails
Abstract
A sail for a wind-powered craft includes a web which forms a
flying shape upon engagement with the wind, flying shape extending
from leading to trailing edges. The web includes a combination of
wind-impermeable and wind-permeable portions disposed between the
leading and trailing edges, with a permeability ratio of
wind-permeable area to wind-impermeable area within a range of
about 5 to 80 percent.
Inventors: |
Gefter; Malcolm L.;
(Lincoln, MA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Gefter; Malcolm L. |
Lincoln |
MA |
US |
|
|
Family ID: |
50474200 |
Appl. No.: |
13/748254 |
Filed: |
January 23, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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61712458 |
Oct 11, 2012 |
|
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|
61721054 |
Nov 1, 2012 |
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Current U.S.
Class: |
114/102.29 |
Current CPC
Class: |
B64D 17/12 20130101;
B63B 2231/40 20130101; B63H 9/067 20200201 |
Class at
Publication: |
114/102.29 |
International
Class: |
B63H 9/06 20060101
B63H009/06 |
Claims
1. A sail for providing wind-powered motive force for a craft, the
sail comprising: a web configured for forming a flying shape upon
engagement with the wind, the flying shape extending from a leading
edge to a trailing edge; said web including a combination of one or
more substantially wind-impermeable portions, and one or more
substantially wind-permeable portions, said wind-permeable portions
being disposed between the leading and trailing edges; and the web
having a permeability ratio of wind-permeable area to
wind-impermeable area within a range of about 5 to 80 percent.
2. The sail of claim 1, wherein the permeability is fixed.
3. The sail of claim 1, wherein the wind-permeable portions are
configured to support the flying shape of the wind impermeable
portion.
4. The sail of claim 1, wherein the permeability ratio is within a
range of about 10 to 40 percent.
5. The sail of claim 1, wherein the flying shape is disposed in the
form of at least one of an upwind mainsail, a headsail, a reaching
sail, a downwind sail, spinnaker, a code zero, and a jib.
6. The sail of claim 1, wherein the flying shape is disposed in the
form of a downwind sail.
7. The sail of claim 1, wherein the flying shape is
asymmetrical.
8. The sail of claim 1, wherein the flying shape is
symmetrical.
9. The sail of claim 8, comprising a clew portion and a tack
portion, the clew portion and tack portions being interchangeable
with one another depending on the orientation of the craft.
10. The sail of claim 8, wherein said wind-permeable portions are
disposed symmetrically on opposite sides of the sail.
11. The sail of claim 1, wherein the wind-permeable portion
comprises a plurality of spaced lines.
12. The sail of claim 11, wherein the sail comprises a leading
portion and a trailing portion, the wind-permeable portion being
disposed within the trailing portion.
13. The sail of claim 12, wherein the wind-permeable portion
extends within a clew portion of the sail.
14. The sail of claim 11, wherein the plurality of spaced lines are
selected from the group consisting of strings, ropes, ribbons,
meshes, and combinations thereof.
15. The sail of claim 11, fabricated from materials selected from
the group consisting of natural fabrics, synthetic fabrics,
plastics, composite materials, synthetic materials, polyamide,
polyethylene terephthalate, aramid, carbon fiber; HMPE (high
molecular weight polyethylene), thermoset liquid crystalline
polyoxazole, and mixtures and laminates thereof.
16. The sail of claim 1, having a foot extending along one edge of
the sail, and a leech extending along another edge of the sail, the
foot and leech each terminating at a clew, wherein the
wind-permeable portion extends in a direction substantially
parallel to the foot, for a distance between about 2 to 50 percent
of the length of the foot.
17. The sail of claim 16, wherein the wind-permeable portion
extends in a direction substantially parallel to the foot, for a
distance between about 5 to 20 percent of the length of the
foot.
18. The sail of claim 16, wherein the wind-permeable portion
extends in a direction substantially parallel to the leech, for a
distance between about 2 to 95 percent of the length of the
leech.
19. The sail of claim 18, wherein the wind-permeable portion
extends in a direction substantially parallel to the leech, for a
distance between about 5 to 60 percent of the length of the
leech.
20. The sail of claim 1, further comprising: a head portion
configured for being coupled to an upper end of a mast disposed on
the craft; a tack portion configured for being coupled near a deck,
bowsprit, or spinnaker pole of the craft; and a clew portion
configured for being coupled to one or more control lines for
trimming the a web supported between said head portion, said tack
portion, and said clew portion.
21. A sail for providing wind-powered motive force for a craft, the
sail comprising: a head portion configured for being coupled to an
upper end of a mast disposed on the craft; a tack portion
configured for being coupled to a deck, bowsprit, or spinnaker pole
of the craft; a clew portion configured for being coupled to one or
more control lines for trimming the sail; a web supported between
said head portion, said tack portion, and said clew portion; said
web including a combination of one or more substantially
wind-impermeable portions in the form of fabric or similar
material, and one or more substantially wind-permeable portions in
the form of widely spaced strings or lines, the wind-permeable
portions extending from the clew portion on a trailing portion of
the sail; a ratio of the wind-permeable portions to
wind-impermeable portions within a range of about 10-40 percent;
and the sail being asymmetrical, or symmetrical wherein
wind-permeable portions are disposed symmetrically on opposite
sides of the sail with the clew and tack portions being
interchangeable depending on the orientation of the craft.
22. A method for configuring a sail for providing wind-powered
motive force to a craft, the method comprising: configuring a web
for forming a flying shape upon engagement with the wind, the
flying shape extending from a leading edge to a trailing edge;
providing the web with a combination of one or more substantially
wind-impermeable portions and one or more substantially
wind-permeable portions disposed between the leading and trailing
edges; and providing the web with a permeability ratio of
wind-permeable area to wind-impermeable area within a range of
about 5 to 80 percent.
Description
RELATED APPLICATION
[0001] This application claims the benefit of U.S. Provisional
Patent Application Ser. Nos. 61/712,458, entitled Structural
Support Scheme for the Replacement of the Clew Section of Sails,
filed on Oct. 11, 2012, and 61/721,054, entitled A Structural
Support Scheme for the Replacement of the Clew Section of Sails,
filed on Nov. 1, 2012, the contents, both of which, are
incorporated herein by reference in their entireties for all
purposes.
BACKGROUND
[0002] 1. Technical Field
[0003] This invention relates to a sail configured to fly in its
working shape while being lighter and having less drag relative to
its lift characteristics, than conventional sails. In spinnaker and
jib embodiments, the sail may have a better ratio of lift to
heeling moment, and allow tighter sheeting angles with less
backwinding of the mainsail, respectively.
[0004] 2. Background Information
[0005] Sails used on sailboats (and on wind powered craft in
general) propel the boat in substantially all points of sail other
than perhaps dead downwind, by creating "lift". Those skilled in
the art will recognize that "lift" is a low pressure zone on one
side of the sail that is created by wind blowing over the convex
surface of a sail when disposed in its working (flying) shape. This
flying shape thus resembles a foil or airplane wing shape, to draw
the craft from the high pressure area on the concave side of the
sail, to the low pressure area on the convex side, to move the
craft forward. The structure of the sail itself creates drag as it
moves through the air, which tends to resist the forward motion of
the craft.
[0006] It is desirable to provide a sail that provides a relatively
large lifting force with a relatively low drag force.
SUMMARY
[0007] According to one aspect of the invention, a sail for a
wind-powered craft includes a web which forms a flying shape upon
engagement with the wind, the web including a combination of
wind-impermeable and wind-permeable portions disposed between the
leading and trailing edges, wherein the web has a permeability
ratio of wind-permeable area to wind-impermeable area within a
range of about 5 to 80 percent.
[0008] According to another aspect of the invention, a sail for a
wind-powered craft includes: a head portion configured for being
coupled to an upper end of a mast; a tack portion configured for
being coupled to a deck, bowsprit, or spinnaker pole of the craft;
and a clew portion configured for being coupled to one or more
control lines for trimming the sail. A web supported between the
head, tack and clew portions includes a combination of one or more
wind-impermeable portions in the form of fabric or similar
material, and one or more wind-permeable portions in the form of
widely spaced strings or lines, the wind-permeable portions
extending from the clew portion on a trailing portion of the sail.
A ratio of the wind-permeable portions to wind-impermeable portions
is within a range of about 10-40 percent. The sail is asymmetrical,
or symmetrical wherein wind-permeable portions are disposed
symmetrically on opposite sides of the sail with the clew and tack
portions being interchangeable depending on the orientation of the
craft.
[0009] In still another aspect of the invention, a method for
configuring a sail for providing wind-powered motive force to a
craft, includes configuring a web for forming a flying shape upon
engagement with the wind, the flying shape extending from a leading
edge to a trailing edge. The method also includes providing the web
with a combination of one or more substantially wind-impermeable
portions and one or more substantially wind-permeable portions
disposed between the leading and trailing edges. The web is
provided with a permeability ratio of wind-permeable area to
wind-impermeable area within a range of about 5 to 80 percent.
[0010] The features and advantages described herein are not
all-inclusive and, in particular, many additional features and
advantages will be apparent to one of ordinary skill in the art in
view of the drawings, specification, and claims. Moreover, it
should be noted that the language used in the specification has
been principally selected for readability and instructional
purposes, and not to limit the scope of the inventive subject
matter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] The present invention is illustrated by way of example and
not limitation in the figures of the accompanying drawings, in
which like references indicate similar elements and in which:
[0012] FIG. 1 is a perspective view of a sailboat employing three
sail types of the prior art;
[0013] FIG. 2 is a view similar to that of FIG. 1, with the three
sail types modified schematically in accordance with the present
invention; and
[0014] FIG. 3 is a schematic diagram of an alternate embodiment of
the present invention.
DETAILED DESCRIPTION
[0015] In the following detailed description, reference is made to
the accompanying drawings that form a part hereof, and in which is
shown by way of illustration, specific aspects in which the
invention may be practiced. These aspects are described in
sufficient detail to enable those skilled in the art to practice
the invention, and it is to be understood that other aspects may be
utilized. It is also to be understood that structural, procedural
and system changes may be made without departing from the spirit
and scope of the present invention. In addition, well-known
structures, circuits and techniques have not been shown in detail
in order not to obscure the understanding of this description. The
following detailed description is, therefore, not to be taken in a
limiting sense, and the scope of the present invention is defined
by the appended claims and their equivalents.
[0016] Where used in this disclosure, the term "axial" when used in
connection with an element described herein, shall refer to a
direction which is substantially parallel to the longitudinal axis
of a wind-powered craft, such as axis a of FIG. 1. The term "wind"
refers to movement of air relative to a craft and/or sail, and
"motive force" refers to a force acting on the craft in a manner
that provides "lift" as described above. The term "leading edge"
refers to that edge of the sail that the wind hits first and the
"trailing edge" or "leech" is that edge that the wind hits last as
it passes over the sail. The term "leading portion" refers to a
portion of the sail extending from the leading edge, and the term
"trailing portion" or "leech portion" refers to a portion of the
sail extending from the trailing edge or leech.
[0017] Referring now to FIGS. 1-3, aspects of the present invention
will be described in detail. As shown in FIG. 1, a conventional
sailboat 10 has three conventional wind-impermeable sails, i.e., a
mainsail 12, a jib 14 and a spinnaker 16. As shown, these prior art
sails, like virtually all sailboat sails, each have a head 18
configured for attachment to an upper end of a mast, a tack 20
configured for attachment near the deck or bowsprit or spinnaker
pole, and a clew 22 at a corner of the sail to which the control
lines for trimming may be attached.
[0018] The present inventor has recognized that in many sails,
under many operating conditions, an area extending from the clew 22
in substantially all directions along the sail (hereinafter the
"clew area" or "clew portion") provides a relatively small amount
of the total lift provided by the sail. This clew area may vary in
size, depending on sail trim and specific shape of a given sail. In
particular examples, it may be as large as substantially all of the
axially extending portion of the sail, e.g., in the event the sail
is a spinnaker. In the case of a jib, this clew area may be the
trailing portion of the sail that shows "return" (i.e., is
backwinding the mainsail) when the jib is tightly trimmed. A
mainsail may also exhibit such a clew area under particular
trimming conditions.
[0019] Turning now to FIG. 2, aspects of the present invention
include a sail that provides reduced drag area, without substantial
loss of "lift" area, by removing wind-impermeable sail material
from the clew area (trailing portion in general), and replacing it
with a wind-permeable portion(s) configured to permit wind to pass
therethrough while still supporting the sail while flying in its
otherwise conventional "working" shape, and while also still
allowing for trimming from the conventional clew position of the
sail. In the embodiments shown and described herein, the
wind-impermeable portion is fabricated from conventional sail
material, including various textiles/fabrics or sheet material from
which sails are conventionally fabricated. The wind-permeable
portion may be a series of "lines", "open meshes" (kite wire,
strings, lines, or generally narrow strips of material) that allow
air to pass substantially freely therethrough. Such a sail has the
advantage of being lighter than a conventional sail due to the
differential weight of the wind-impermeable "fabric" relative to
the wind-permeable support configuration.
[0020] As shown in FIG. 2, in each of the three otherwise
conventional sails, 12', 14', 16', wind- impermeable web in the
clew area has been replaced with wind-permeable portions 30 in
accordance with the teachings of the present invention. It will be
understood that this FIG. 2 is shown for illustrative purposes
only, and that the actual area of wind-permeable portions 30 may be
larger or smaller than that shown. In addition, a plurality of
wind-permeable portions may be provided, which may be spaced from
one another on the sail. Moreover, embodiments greater or fewer
numbers or types of sails, without departing from the scope of the
present invention.
[0021] In the particular examples shown, the wind-permeable
portions 30 may take the form of a system of "strings" 32 that
allow air to pass through, and which are disposed so that the
portions 30 effectively extend from the clew 22 in substantially
all directions, to form the "clew area". The size and shape of the
"clew area" of a particular sail may vary depending on the sail's
purpose (runner, reacher, jib, etc.) and anticipated application,
as will be discussed in greater detail hereinbelow. Moreover, as
discussed above, the area of fabric removal need not extend
continuously as shown, but may be discontinuous, e.g., disposed as
a series of patches disposed in spaced relationship to one another
along the sail. The wind permeable portion also may not necessarily
include the clew 22 itself. In particular embodiments, however, the
wind-permeable portion is disposed closer to the trailing edge or
leech 34 of the sail, than to the leading edge 36 of the sail, as
best shown with respect to sail 12'.
[0022] As mentioned, the size of the wind-permeable portion is not
limited to those shown in the Figures, but rather, may depend on
various factors, such as the sail type (e.g., main sail, jib,
spinnaker, runner, reacher, etc., including whether the sail is
asymmetrical or symmetrical), the particular application, including
type of craft (e.g., sailboat) and the trim or wind direction
relative to the direction of movement of the craft.
[0023] In particular aspects of the invention, the wind-permeable
portion(s) is sized and shaped to provide the sail with a ratio of
the wind-permeable portion(s) to wind-impermeable portion(s)
(hereinafter, the "permeability ratio") within a range of about 5
to 80 percent. In other aspects, the ratio may be within a range of
about 10 to 40 percent. Moreover, in various aspects, the
wind-permeable area may extend, in a direction substantially
parallel to the foot 37 of the sail, a distance between about 2 to
50 percent of the length of the foot. In particular embodiments,
this distance may be between about 5 to 20 percent of the length of
the foot. The wind-permeable area may also extend, in a direction
substantially parallel to the leech 38 of the sail, a distance
between about 2 to 95 percent of the length of the leech. In
particular embodiments, this distance may be between about 5 to 60
percent of the length of the leech.
[0024] It is contemplated that in particular embodiments, the ratio
of wind-permeable to wind-impermeable portions will be fixed for a
given sail, and that users may simply maintain an inventory of
sails of different ratios. The user may then choose from among the
sails of various ratios, e.g., based on current wind conditions,
etc.
[0025] In other embodiments, instead of a fixed ratio, sails may be
provided with a variable ratio, such that a user may adjust the
ratio of a particular sail. For example, a sail may be provided
with a series of removable web portions, which may be selectively
removed and replaced by the user, such as may be desired to respond
to changing wind/weather conditions. Alternatively, in the event
the wind-permeable portions are formed by a series of lines or
strings as shown, such lines may be configured for being lengthened
or shortened to change the shape of the sail, and/or to change the
permeability ratio. These lines, whether of fixed length (for fixed
ratio) or adjustable length (for variable ratio), may terminate at
the clew 22 (e.g., at a clew ring or similar attachment point) of
the sail as shown, where they may be connected to a conventional
control sheet.
[0026] As mentioned above, the size, shape and ratio of the
wind-permeable area for a particular sail may be configured based
on the desired application, and may thus depend on factors such as
the intended sail shape/function, intended sheeting angle, and/or
angle of attack to the wind.
[0027] It should also be recognized that in accordance with the
teachings hereof, the wind-permeable area may be applied to
substantially any portion of the sail to which wind is not expected
to be "attached" during its anticipated operation. One skilled in
the art will recognize that such areas may be identified by
examining telltales along the body of a conventional sail. The area
of non-attached flow along, for example, the foot and leech of the
sail in the embodiments shown in FIG. 2, may then replaced by a
wind permeable system as described herein. The skilled artisan will
also recognize, in light of the teachings hereof, that the areas of
conventional sails at which the wind is not "attached" may be
determined by employing well-known computer simulations using
conventional computational fluid dynamic algorithms looking for
attached flow or pressure differentials under various operational
(e.g., wind, sheet, angle of attack, etc.) conditions.
[0028] The sail, including both the wind-impermeable and
wind-permeable portions may be fabricated from any number of
suitable materials. The wind-impermeable portions may be fabricated
from any number of materials conventionally used for sails,
including fabrics made from natural or synthetic fabrics, plastics,
composite materials, mixtures of the same, and/or laminates of the
same. Examples of such materials include synthetic materials such
as: polyamide (Nylon); polyethylene terephthalate such as
DACRON.RTM. (DuPont); aramid such as KEVLAR.RTM. (DuPont),
TWARON.RTM. (Teijin Aramid), and TECHNORA.RTM. (Teijin Aramid);
carbon fiber; HMPE (high molecular weight polyethylene) such as
SPECTRA.RTM. (Honeywell), and DYNEEMA.RTM. (DSM IP Assets B.V.);
thermoset liquid crystalline polyoxazole, such as ZYLON.RTM. (Toyo
Boseki Kabushiki Kaisha Corporation), etc.
[0029] These same materials may be used to fabricate the lines or
strings of the wind-permeable portions. In this regard, the lines
may be fabricated from substantially any material capable of
supporting the load (e.g. spectra) of the sail. The number of
strings and associated attachment points may vary depending upon
the load and desired working (flying) shape of the sail.
[0030] As mentioned above, it should be recognized that aspects of
the present invention may be applied to symmetric, as well as
asymmetric, sails. The embodiments shown and described hereinabove
with respect to FIG. 2 include asymmetrical sails (e.g., a main
sail, jib, and spinnaker), in which the clew, head, and tack are
disposed at fixed locations on the sail regardless of the
orientation of the boat. In other words, the same portions of the
sail respectively serve as the clew, head, and tack regardless of
whether the boat is sailing at a port tack, a starboard tack, or
dead downwind. For example, those skilled in the art will recognize
that to jibe a conventional spinnaker, the clew is taken from one
side and passed to the opposite side of the boat, to effectively
turn the spinnaker inside out on opposite jibes.
[0031] Turning now to FIG. 3, an embodiment of the present
invention includes a symmetrical sail (such as a spinnaker as
shown), in which the clew and tack may be interchanged with one
another, e.g., based on the orientation of the boat. In this
regard, the spinnaker 16'' may be moved from one side of the boat
to the opposite side of the boat (i.e., the spinnaker does not turn
inside out as does the asymmetrical sail discussed hereinabove), so
that the location of the sail that was the tack effectively becomes
the clew, and vice versa. This may be accomplished by physically
detaching the tack from the spinnaker pole, pulling the sail across
the boat, and then attaching what was the clew to the spinnaker
pole so that it now becomes the tack.
[0032] In this alternate embodiment, both of the "clew areas" of
the sail, i.e., those areas on opposite sides of the sail that
alternate between clews and tacks depending on the orientation of
the craft, may be replaced with strings or other wind-permeable
portions 30' as shown.
[0033] This approach effectively permits an otherwise conventional
asymmetric spinnaker to be configured as a symmetric spinnaker in
which the conventional head 18 is attached to the mast as shown,
while the tack is replaced by an attachment 40 to the bow sprit in
the middle of the foot 37 of the sail. The foot may be attached
centrally to the bow sprit or alternatively, may be configured to
slide along the bow sprit, e.g., between points "A" and "B" as
shown, to provide the sail with greater range of movement from side
to side of the boat.
[0034] It should be recognized that aspects of the invention may
include various placements and shapes of the particular areas
defined by the removed sail fabric. Although the present invention
has been described with reference to specific exemplary aspects, it
will be evident that various modifications and changes may be made
to these aspects without departing from the broader spirit and
scope of the invention. Accordingly, the specification and drawings
are to be regarded in an illustrative rather than a restrictive
sense.
[0035] In addition, although the present invention has been
described with reference to sails used to move a sail boat, it
should be recognized that aspects of the present invention may be
applied to substantially any type of craft configured to support a
flexible material in a working shape configured to generate a
motive (lift) force. Examples of such craft may include various
types of sail boats ranging from sail boards and kite surfers to
large multi-masted vessels, and various aircraft, including
gliders, hang gliders, ultra-light aircraft, parachutes, powered
parachutes, etc.
[0036] It should be further understood that any of the features
described with respect to one of the aspects or embodiments
described herein may be similarly applied to any of the other
aspects described herein without departing from the scope of the
present invention.
* * * * *