U.S. patent application number 17/352234 was filed with the patent office on 2022-02-24 for advanced high efficiency mainsail.
This patent application is currently assigned to Donald Butler Curchod. The applicant listed for this patent is Donald Butler Curchod. Invention is credited to Donald Butler Curchod.
Application Number | 20220055726 17/352234 |
Document ID | / |
Family ID | |
Filed Date | 2022-02-24 |
United States Patent
Application |
20220055726 |
Kind Code |
A1 |
Curchod; Donald Butler |
February 24, 2022 |
ADVANCED HIGH EFFICIENCY MAINSAIL
Abstract
A sail comprising a rotating flexible mast sleeve wrap
surrounding the mast and attached to a sail track for controlling
the movement of the sail. The sleeve assembly is slotted to allow
for partial rotation of the sleeve wrap, the sail track and the
sail, so that the sleeve wrap, the sail track and the sail rotate
to form an aerodynamic shape on the lee side of the rotating
flexible mast reducing aerodynamic losses.
Inventors: |
Curchod; Donald Butler;
(Avalon Nsw, AU) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Curchod; Donald Butler |
Avalon Nsw |
|
AU |
|
|
Assignee: |
Curchod; Donald Butler
|
Appl. No.: |
17/352234 |
Filed: |
June 18, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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63067310 |
Aug 18, 2020 |
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International
Class: |
B63H 9/08 20060101
B63H009/08 |
Claims
1. A sail attached indirectly to a fixed mast, the sail comprising:
a rotating flexible mast sleeve wrap surrounding the mast and
attached to a sail track for controlling the movement of the sail,
wherein the sleeve assembly is slotted to allow for partial
rotation of the sleeve wrap, the sail track and the sail, so that
the sleeve wrap, the sail track and the sail can rotate to form an
aerodynamic shape on the lee side of the rotating flexible mast
reducing aerodynamic losses.
2. A sailing boat with a mast and boom, wherein the majority of the
open space between the boom and deck or coach house has a skirt
extending horizontally from the mast to more than half-way to the
mainsail end or clew, wherein the skirt reduces the majority of the
otherwise loss of efficiency and drive under a traditional
boom.
3. The sailing boat of claim 2, wherein the skirt wraps around the
base of the mast so that there are two skirts behind the mast.
4. The sailing boat of claim 2, wherein the skirt allows for
vertical movement of the boom end.
5. The sail of claim 1, wherein the mast sleeve wrap and sail track
assembly house a vertical furling tube assembly for vertically
furling the sail.
6. The sail of claim 1, wherein a tack of the sail is not fixed but
allows for the partial rotation of the sail tack area, so that
sleeve wrap, sail track and sail tack rotate to form an aerodynamic
shape on the lee side of mast at the foot of the sail, reducing
aerodynamic losses at the foot of the sail.
7. The sail of claim 1, wherein the fixed mast has non-circular
cross section, having a substantially semicircular-shaped rear
radius and a front radius smaller than the rear radius.
8. The sail of claim 1, wherein a root of a spreader has a
horizontal central point which is forward of the front to back
center of the mast section to allow for maximum rotation of a
rotating sail track or vertical furling system.
9. A sailing boat of claim 2 where a skirt is furled by at least
one vertical furling tube behind the mast and predominantly below
the boom.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] The present application claims the benefit of the earlier
filing date and priority to U.S. provisional application Ser. No.
63/067,310, filed on Aug. 18, 2020, the content of which is hereby
incorporated by reference herein in entirety.
TECHNICAL FIELD
[0002] The subject matter described herein, relates to additions to
fixed masts and booms and or mainsails in order to significantly
improve a mainsails efficiency.
BACKGROUND
[0003] Mainsails with traditional fixed masts with stays and booms
have very poor efficiency. Wind tunnel testing of sails with fixed
masts sailing upwind and reaching have shown that .about.15% is
lost at the head of the sail, .about.30% (or even 40% if there is a
gap between mast and sail) is lost at the mast to sail connection,
and .about.25% is lost at the foot.
[0004] The lee or backside of the mast to sail connection of a
traditional fixed mast forms a pocket of air which prevents laminar
flow from the mast to the sail which laminar flow on the lee side
of a sail is most important for efficiency. This prevention of
laminar flow on the lee side, upon which drive relies, causes this
.about.30% loss (being for a round mast with no gap between mast
and sail). If a gap is present and mast is oval, then this loss can
be up to .about.40%. These figures are in comparison to an airfoil
shaped mast which rotates.
[0005] This traditional fixed mast and sail arrangement described
above, is analogous to a permanently stalling vertical wing.
Efficient airfoil shaped rotating masts however are not practical
for the majority of sailing boats. Traditional booms used in the
majority of sailboats, are mostly situated well above decks and
coach houses, this allows low-pressure air from the lee side to
leak to the high-pressure windward side under the boom creating a
drag rotor and results in a 25% loss of efficiency and drive. Such
a sail is similar to a vertical wing. If an aircraft were to use a
traditional fixed mast and boom arrangement as do sailboats, it
could not take off.
SUMMARY
[0006] It is the object of this invention to provide a means to
largely eliminate the mast to sail and under boom losses detailed
above, by providing a simple practical means which can be applied
to the majority of sailing boats and which does not require
significant changes to traditional fixed stayed masts and
booms.
[0007] This application will show how an aerodynamic rotating
fairing can be added to a fixed stayed masts and how an aerodynamic
skirt can be attached below booms, to eliminate the majority of
inefficiency now present in a large majority of sailing boats.
[0008] These improvements in efficiency outlined in this
application, also give the mainsail drive which is lower and
further forward than a traditional fixed mast mainsail, allowing a
smaller more easily handled mainsail to be used, while also
allowing for a lighter stiffer boat and a boat which is able to
point higher.
BRIEF DESCRIPTION OF DRAWINGS
[0009] FIG. 1 shows a cross section of one method of achieving a
rotating airfoil mast sail connection.
[0010] FIG. 2 shows a cross section of another method of achieving
a rotating airfoil mast sail connection.
[0011] FIG. 3 shows a cross section of a third method of achieving
a rotating airfoil mast sail connection.
[0012] FIG. 3A shows a cross section of an alternative to FIG. 3 of
achieving a rotating airfoil mast sail connection.
[0013] FIG. 4 shows an elevation of a typical fixed mast sailboat
with a mast fairing and skirt.
[0014] FIG. 5 shows a section through skirt of FIG. 4.
[0015] FIG. 6 shows a partial elevation of a boat with a mainsail
and skirt.
[0016] FIG. 7 shows an isometric part detail of a sail head to
halyard connection.
[0017] FIG. 8 shows an alternate isometric part detail of a sail
head to halyard connection.
[0018] FIG. 9 shows another alternate isometric part detail of a
sail head to halyard connection.
[0019] FIG. 10 shows yet another alternate isometric part detail of
a sail head to halyard connection.
[0020] FIG. 11 shows an isometric part detail of a sail head to
halyard connection.
[0021] FIG. 12 shows an isometric part detail of a mainsail tack
connection method.
[0022] FIG. 13 shows an isometric part detail of an alternative
mainsail tack connection with a roller furling boom.
[0023] FIG. 14 shows an isometric part view of another tack
connection method
[0024] FIG. 15 shows a partial cross section of a rotating sliding
car or slug to sail connection assembly.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0025] FIG. 1 shows a mast cross section 100 with mast 102 and a
mast fairing wrap 101. A sail track 104 connects to fairing 101 via
bolt rope connection means 105A and a screwed connection at 105B.
Any other normal other connection such as rivet, adhesive, etc., is
also possible. Fairing 101 wraps around a typical oval mast 102.
Note a round mast shown dotted at 116 or any shaped mast can also
be used.
[0026] A sail 106 is shown connected to sail track assembly 104.
Twin optional bolt rope connections and wraps shown dotted at 114A
and 114B are also possible in place of the single mast wrap 101.
Fairing wrap 101 would be a flexible member, which easily deforms
to rotate around an oval or other mast shape. A secondary wrap
shown dotted at 112 and battens, shown dotted at 110A and 110B
could be added if desired in order to more rigidly contain wrap 101
and sail track 104 on mast 102. Wrap 112 could be connected to wrap
101 using hook and loop fastening.
[0027] Spaced brackets shown dotted at 107 could also be used to
secure position of sail track assembly 104. Note, although bolt
rope sail tracks are shown for simplicity, any type of sail track
can be used. Wind direction is shown by arrow 118. Fairing wrap 101
allows airflow to smoothly travel around back, lee side, of mast
shown by arrow 120 so that laminar flow is largely maintained over
the lee side of the sail, in order that the maximum efficiency is
obtained, and the .about.30% to .about.40% traditional mast to sail
losses are eliminated.
[0028] It is intended that the sail track 104 would be close the
mast at the top and approximately as shown in figure two at the
bottom, by using a tapered flexible fairing wrap 101. The fairing
wrap 101 would also have slots, appropriately placed to account for
spreaders and other items attached to a mast, when the fairing
assembly 100 rotates.
[0029] Although almost any mast profile will allow this rotation,
the optimal mast section profile has a smaller radius at the front
shown at 117 compared to the radius at the rear, which ideally is
semi-circular. This configuration allows rotation of the sail track
at the rear and gives an improved aerodynamic profile on the lee
side of the mast. Note front radius 117 can be in the form of an
ellipse or a parabola. In this way, a relatively simple connection
is achieved, while allowing an aerodynamically efficient mast sail
connection.
[0030] FIG. 2 shows a typical oval mast section 200, according to
another method of providing a simple and more efficient aerodynamic
mast to sail connection. This second method allows for a standard
sail track fixed to a non rotating mast to be used. As shown, a
fixed oval mast 202 with a bolt rope sail track 203 and sail 204.
Note any reasonably shaped mast and any style of mast track can be
used.
[0031] Surrounding mast is a semi-circular bracket 212 which holds
two vertical members or fairing pieces 206A and 206B, which are
connected to bracket 212 at its outer ends. Bracket 212 would be
ideally one of a number spaced along mast 202 whilst fairing pieces
206A and 206B would run between them. Brackets 212 and fairing
pieces 206A and 206B would be free to rotate around mast 202.
[0032] For a typical mast which is not round, a spacer 214 or
spacers shown at 214A and 214B could provide the effect of a round
mast allowing bracket 212 and firing pieces 206A and 206B to
readily rotate. Spacers 214A and 214B are optional and provide an
optimal reliable rotation around a non-circular mast, but are not
indispensable.
[0033] Spacers 214A and 214B may be fixed along the mast 202 to
coincide with brackets 212. Alternatively, brackets 214A and 214B
could be floating on mast and loosely retained by brackets 216 and
212. A bracket 216, optional according to certain aspects could be
provided to contain rotating bracket 212. If bracket 216 is not
used, a tensioning line would be required top and bottom to keep a
wrap 208 against mast 202.
[0034] Also shown dotted at 216B is a restraining tension member
which would attach to either mast or bracket 214. These tensioning
lines would preferably be attached to each side of bracket 212,
both at the top and bottom. If used, bracket 216 would be attached
to a spacer or spacers 214A and 214B. using in one option,
attachment bolt holes shown at 215. Bracket 216 could also be of a
flexible or fabric material, attached to top and bottom of spacers
214A and 214B.
[0035] An aerodynamic wrap 208 attaches to each of the members or
fairing strips 206A and 206B and wraps around mast between bracket
assemblies 212. Note fairing members 206A and 206B are optional,
since wrap 208 could connect directly to brackets 212. Assemblies
of brackets 212 would be spaced along the mast 202 with wrap 208
and fairing pieces 206A and 206B between them.
[0036] Since assemblies with bracket 212 would be relatively thin
and would be spaced well apart, the majority of the mast would have
a rotating flexible aerodynamic wrap 208 and fairing pieces 206 A
and B to provide an aerodynamic rotating fairing on a fixed mast.
In certain embodiments, fabric wrap 208 could have battens shown
dotted at 207A and 207B attached to bracket 212, replacing fairing
pieces 206A and 206B with fabric wrap 208 between battens, as long
as the wrap is tensioned top and bottom.
[0037] The fairing assembly 200 may extend from the top area of the
sail to a position above the boom, with a gap between fairing and
boom, to allow for flaking of the mainsail. Alternatively, if the
fairing assembly was required to extend close to the boom shown at
406A in FIG. 4. A removable or unfolding flexible or rigid fairing
could be used to allow for flaking could be provided. Wind
direction is shown at 218. Airflow around the lee side of sail 202
is shown by arrow 220.
[0038] In accordance with one or more aspects, the aerodynamic
rotating fairing assembly 200 causes lee airflow to be largely
laminar around mast and sail, as shown by arrow 220, eliminating
the majority of the .about.30% to .about.40% loss of a traditional
mainsail, thus allowing a much more efficient, higher pointing mast
and mainsail which can be smaller, lighter and more easily managed
while still providing increased efficiency drive and
performance.
[0039] Note bracket 212 is shown with outer portion 212A being cam
shaped. This allows fairing to retain its shape when rotating,
since if the mast is not round the fairing would become looser as
it rotates from its central position, this cam action against
bracket 216 allows aerodynamic fairing wrap to retain its shape.
Please also note, bracket 216 could also be flexible in nature.
[0040] FIG. 3 shows a cross-section of a typical mast with an
alternative rotating aerodynamic fairing assembly 300 in which the
sail track 306 is not fixed directly to mast 302 but can rotate.
FIG. 3 has mast section 302 with a bracket 304 and sail 308. Two
rigid or semirigid fairings 310A and 310B are attached to the
bracket 304. A sail track 306 is also attached to the bracket 304,
a bolt rope type sail track is shown for simplicity, however here
and elsewhere, any type of sail track can be used.
[0041] It should also be noted that sail track 306 may also be
independently rotating on mast 302, rather than being attached and
rotating with bracket 304. This is achieved in one method, by sail
track 306 being attached to a separate wrap shown dotted at 311. It
should be further noted that a sail track could be attached
directly to the fairings 310 A and B, shown dotted at 306A, in
place of sail track position 306. Alternatively a mainsail 308A
could be attached to a furling tube shown dotted at 309, attached
top and bottom to bracket or brackets 304.
[0042] A flexible wrap is shown at 312 wrapping around mast 302
with each end fastened to fairings 310 A and B. The flexible
fairing wrap 312, could alternatively wrap around mast to positions
307A and 307B with 310A and 310B being spaced battens. Spaced
battens in this case, would be connected to a bracket 304. In its
simplest form, if aerodynamic fairing wrap 312 is tapered, with the
top being least in circumference, then only one batten at the
bottom would be required, and no brackets would be necessary.
[0043] If a flexible wrap and at least one batten is used, then
wrap would be tensioned by lines top and bottom. This flexible wrap
and batten system could also be an alternative construction for the
previous arrangements of FIGS. 1 and 2. Note also that fairing
members 310A and 310B are optional. Bracket 304 could extend to
position shown by 307A and 307B or to sail track 316A and connect
directly to the flexible wrap, if wrap member is tensioned top and
bottom.
[0044] In this way, a simple efficient rotating aerodynamic fairing
can be provided which rotates around the majority of a fixed mast.
Slots would be provided in the rotating fairing where necessary to
allow for spreaders and other mast attachments. The assembly 300
would cover the majority of the mast above the boom, while bracket
304 could be the same length as the fairings or be of narrow depth
and be spaced along the mast at appropriate intervals.
[0045] The fairing assembly bottom 300 would extend to a position
above the boom, shown at 406A in FIG. 4, to allow for flaking of
the mainsail. Alternatively, if the fairing assembly was required
to extend close to the boom, a removable or unfolding flexible or
rigid fairing close to the boom could be used to allow for flaking.
A wind direction is shown at 314. Airflow around the lee side of
the mast 302 is shown by arrow 316. This aerodynamic rotating
fairing assembly 300, causes lee airflow to be largely laminar
around the lee side of the mast and sail, shown by arrow 316,
eliminating the majority of the .about.30% to .about.40% loss of a
traditional mainsail, thus allowing a much more efficient, higher
pointing mainsail and mast which can be smaller, lighter and more
easily managed while still providing increased efficiency, drive
and performance.
[0046] Bracket 304, fairings 310A and 310B and sail track 306 or
306A are shown as separate pieces which would be screwed, glued or
bolted together, if sail track 306 is not separately rotating, but
it is possible to construct these four pieces as one length or
short lengths for ease of construction and shipping and then
connected together. The preceding has shown how a large portion of
the inefficiency of a mainsail may be significantly reduced or
largely eliminated at the traditional fixed mast sail connection,
but this still leaves a significant loss at a traditional boom.
[0047] FIG. 3A shows a part section of a rotating firing assembly
320, with mast 321 and rotating bracket 324, similar to that of
FIG. 3, except that sail 328 has a double luff which connects to
fairing strips 322A and 322B. one side of sail luff 328 connects to
fairing strip 322A via a roller sail track, while the other side of
sail luff connects to luff strip 322B via a bolt rope sail track
330. As in FIG. 3, note, any type of sail track can be used and
would usually be the same on both sides. A flexible wrap extends
from fairing strip 322A to 322B, in order to provide a rotating
fairing assembly which is highly efficient. In some embodiments,
bracket 324 can be spaced or continuous.
[0048] It should be noted that any element in any of the above
figures may be applied to and other of the above figures. Although
the preceding is most applicable to a fixed mast, it can also be
used with a rotating or partially rotating mast.
[0049] FIG. 4 shows a method of reducing the remaining boom loss
shown by wind tunnel testing to be approximately 25%. A boat 400
with fixed mast 402 and spreaders 404 are shown as having an
aerodynamic fairing 406, sail 408 and boom 416. Beneath boom 416
are two skirts 414A and 414B, surrounding yang 426 one being hidden
behind the other. Skirts 414A and 414B, extend vertically from
under boom 416 to close to deck (or top of a coach house) 421.
Skirt or skirts each have at least one vertical batten, shown at
420, if skirts are cut diagonally as at 419.
[0050] Skirts 414A and 414B may have clear panels, one at 424 and
skirt or skirts would be tensioned by an outhaul or outhauls, not
shown. The front of skirts 414 are shown having two vertical
furlers 430A and 430B hidden behind. These two furling tubes are in
one embodiment, attached directly or indirectly to boom 416.
Furlers can be manually, electrically or hydraulically operated to
retract or deploy Skirts 414A and 414B horizontally. At the front
of the skirts, furlers 430A and 430B is a fairing 432 which wraps
around bottom of mast 402 to streamline mast and front of skirt
furlers 430A and 430B. Note, a simpler but not as effective
alternative is to use a triangular skirt with bottom shown dotted
at 422 running directly from and elastically connection at bottom
of mast 402 to near the outer portion of boom 416.
[0051] It would also be possible to have one skirt which wraps
around the bottom of mast 402 having a double panel from the mast
bottom to just behind the yang 426, which skirt is deployed and
stowed or removed manually as required. Bottom of skirt 414 would
need also need to be elastically tensioned in this case to allow
for difference in tension by vertical movement of the boom 416.
Further, top of skirt or skirts 414A and 414B could hang from loops
over boom, or run in tracks under the boom 416 (neither shown).
[0052] One method of attachment of skirt 414 directly to bottom of
mast 402 is for top most skirt fronts to be connected to mast
bottom at 401 and cut on a diagonal so that bottom of front of
skirts 414 wrap around each side of mast 402 shown by dotted
diagonal line 433. In this arrangement, elastic tension would be
maintained at each bottom corner 431A and 431B, so as to allow for
horizontal movement caused by vertical adjustment of end of boom
416. Skirt or skirts may also be stowed by simply raising
vertically and tying beneath the boom.
[0053] If skirts 414A and 414B are simple wraps around the mast as
described above, they could alternatively be deployed or stowed by
being part of a lazyjack system, raised by lazyjacks 410A and 410B
to dotted position 412. Note diagonal rear of skirt 419, does not
need to extend to mainsail tack, but may be shorter as shown at
419A, in which case batten would be positioned at 420A. To be
effective in reducing the inefficiency of the mainsail due to under
the boom losses, the skirt would need to block more than .about.35%
of the distance from the mast to the clew of the mainsail. This
skirt system as described above, being easily stowed and deployed,
could be used when maximum efficiency or drive is required.
[0054] In small boats or dinghies, where maximum performance is
desired, but a skirt would interfere with crew transfer from one
side of the boat to the other during tacks, then clew of skirt
could be collapsed, partially or fully, toward the mast during
tacks shown by arrow 417. Optimally in this arrangement, the end of
skirt or skirts 414A and 414B could be elastically tensioned in
direction of arrow 417. Skirt outhaul would be released during a
tack in order for skirt end or ends to retract to allow crew to
cross under the boom, and then a skirt outhaul would be tensioned
to deploy the skirt for efficient sailing, after tack is
completed.
[0055] Shown at 404 is a spreader base which has a horizontal
center well forward of the normal mast horizontal center, in order
for the maximum rotation of the rotating sleeve and sail track
proposed in this disclosure. Note also flexible wrap 406 is slotted
a mast forestay and spreaders, to allow for rotation of the wrap
assembly.
[0056] Alternatively, a single skirt could be employed under boom
416 if the single yang 426 is replaced by dual vangs, one on each
side of boom 416. In this case, a rotating sleeve around mast 402
connected to the single skirt would be used. If a single skirt is
used, a single vertical skirt furler could also be used in place of
dual furlers of FIG. 5.
[0057] FIG. 5 shows a part cross section at 436 of FIG. 4. With
mast section 502, boom part 505 and flexible mast wrap fairing 522,
which all rotate around gooseneck 504 and mast 502. A yang portion
is shown at 508. Under boom 505 and connected to it, is bracket 517
which pivots on boom 505 at 515. Twin vertical furling tubes are
shown at 518A and 518B. Note, furling tubes may also be fixed and
not rotating. Attached to furling tubes 518A and 518B are deployed
skirts 514A and 514B, also shown at 414 of FIG. 4.
[0058] Air direction is shown by arrow 520. Flexible mast wrap 522,
provides an aerodynamic fairing to allow air to flow around mast
505 and skirt 514A, depicted by arrow 507 causing the air thus
flows smoothly around back side of skirt shown by arrow 507. This
allows the arrangement to not only block the .about.25% under boom
losses, but also adds to the drive of the mainsail.
[0059] A furling control mechanism could be attached to each
furling tube 518A and 518B or could be a single mechanism housed
between furling tubes, shown dotted at 516. Bracket 517 can
alternatively be fixed so as to position furling tubes
symmetrically about boom 505. Another alternative arrangement is to
have one central skirt shown dotted at 512 and wrapping around mast
at 519A and 519B, with an elastic lower portion to allow for boom
movement.
[0060] For this single skirt arrangement, above, 512, 519A and 519B
to be of maximum aerodynamic efficiency, there would need to be
twin vangs, shown connected to each side of boom 505 dotted at 519A
and 519B. With twin vangs, it is also possible to employ one furler
positioned centrally at 516. It should be noted, all skirts would
be of flexible material.
[0061] FIG. 6 shows a partial elevation of a boat 600 with fixed
mast 602, traditional mainsail 608, traditional boom 624, and front
pivot 639. Mainsail has clew outhaul 618. Mast 602 has an optional
rotating sleeve and sail track shown dotted at 604. Note, the
rotating sleeve connection may also be connected via a zipper shown
partially dotted at 606.
[0062] A skirt 636 wraps around mast 602 with clew 624 of skirt 636
positioned on each side of boom, around yang, not shown. Skirt has
top 617 close to bottom of mainsail 608, or even overlapping for
maximum effect, shown dotted at 613. Skirt bottom 633 would be
close to deck (or coach house top).
[0063] Skirt 636 has twin clews, one shown at 624 tensioned with
outhaul line around pulley 620 and back along (or inside) boom. If
skirt 636 is of one piece, wrapping around mast 602, in order for
boom to move upward, skirt outhaul 620 needs to be elastic. This
elasticity can be achieved by an elastic line, shown dotted at 632.
Alternatively a spring or air cylinder could be used for
tensioning. An alternative to an elastic skirt outhaul 632, is for
a second boom for the skirt clew to be used, as shown at 625. This
second boom, could be pivoted at 614. Secondary skirt boom 625
would be a separate boom 622. It could be of any cross section or
be a channel as shown, dotted, surrounding bottom of boom 622. This
arrangement allows main boom to pivot vertically upwards, with a
non-elastic skirt or skirt outhaul. [0064] Pivot of secondary skirt
boom 625 is shown attached to main boom 622, but it's pivot 614
could be attached directly to mast 602
[0065] Foot of sail 616 is undercut at 614 so as to make foot of
sail shorter than max chord 610 shown dotted, with batten 612. In
this way a shorter skirt can be used so that combined skirt 636 and
sail 608 eliminates the majority of the normal 25% foot loss under
the boom 622. By providing a shortened mainsail foot, skirt 636
length, can also be reduced, allowing maximum clearance at the rear
of the boat as well as a reduced boom length.
[0066] A batten 628 of skirt 636 is required to keep corner of
skirt 630 from curling. Each side of skirt 636 can also be attached
at 630. Skirt 636 could also be cut on the diagonal shown dotted at
634, to provide a partial reduction of the normal 25% foot loss. It
should also be noted that one outhaul could be used if the main
outhaul and skirt dews are attached to foot of sail 618.
[0067] When deployed, the skirts shown, offer a number of important
advantages, it will reduce the height of the center of effort of
the mainsail, which will reduce heeling. An added skirt will also
not only block the traditional under boom losses, shown by wind
tunnel tests to be approximately 25%, but if designed correctly as
in FIG. 5, or as part of the mainsail as in FIG. 6 and if skirts
are aerodynamically shaped, a skirt will add to the mainsail drive,
and turn a traditional 25% loss into a .about.30% gain, due to the
added drive. This in turn will further allow a smaller lighter
mast, sail and boom, while at the same time adding significant
performance and easier handling.
[0068] It should be noted that the skirts shown above need not
block the space below the boom completely, but to be effective
should block at least 25% of the area between the boom and deck, or
coach house. It should also be noted that any element in the above
FIG. 4, 5 or 6, may be applied to any of the other FIG. 4, 5 or
6.
[0069] In order for the rotating mast sleeve shown above to be of
maximum effect, the track and head of the sail must be able to
rotate, FIG. 7 shows part view of a mast top 700 with oval mast
701. A rotating mast sleeve 716 with bolt rope sail track 718 and
attached mainsail 720. A halyard 710 is attached to sail head at
714. Halyard passes over a sheave 706 and down inside mast 701 at
712. Sheave 706 is held in an arm 708 rotating in a bracket 702,
which is fixed to mast, one point of attachment being 722. Bracket
arm 708 pivots in bracket 702 at 704. Pivot 704 and bracket 702 are
positioned as shown so that halyard 710 allows head of sail, sail
track 718 and sleeve wrap 716 to rotate around the oval mast 701 in
order for the maximum airfoil shape of the sleeve and sail to be
achieved on the lee side.
[0070] FIG. 8 shows another method of achieving a rotating mainsail
head with an alternative mast top configuration 800 having mast
801, rotating sleeve wrap 808 sail track 812 and sail 814. Head of
mast 801 is undercut at 804 and 804A so that halyard sheave 802 is
positioned near the center of mast 801 rear radius to allow halyard
806 connection 810, sail track 812 and sail head 814 to rotate
freely as required. In this way, sleeve 808 and sail 814 is able to
form an optimal aerodynamic shape on lee side of mast 801.
[0071] FIG. 9 shows another method of achieving a rotating mainsail
head with an alternative mast top 900 having mast 902, rotating
sleeve wrap 910, sail track 911 and sail head 912. Top portion of
oval mast 902 is circular and carries loose rotating bracket 904.
Attached to end of bracket 904 is a block or sheave 906 a halyard
907 is attached to head of sail 912 at 908. Halyard runs through
block or sheave 906 and down within sleeve shown dotted at 907A. In
this way sleeve 910, sail track 912 and head of sail is able to
rotate as required for maximum sail efficiency.
[0072] FIG. 10 shows another method of providing a mast top halyard
connection. Mast top 1000 has an oval mast 1001, rotating sleeve
wrap 1018, sail track 1016 and sail head 1014. Attached to mast top
1001 is a bracket 1004, affixed to mast at two points, one shown at
1002. Slidably attached to bracket 1004 is a halyard block 1006,
which is able to slide horizontally around bracket 1004.
[0073] Sail head 1014 has a halyard attached at 1010 which passes
through block 1006 and down inside sleeve 1018 shown dotted at
1012. Bracket 1004 could also be of soft material or rope, attached
to points, one shown at 1002. An alternative soft loop shown dotted
at 1020 could also be used in place of 1004, with loop 1020
surrounding mast 1001 and held by side brackets, one shown at 1022.
In this way sleeve 1018, sail track 1016 and head of sail is able
to rotate as required for maximum sail efficiency.
[0074] FIG. 11 is yet another method of providing a sail head and
halyard connection which allows rotation of sleeve wrap and sail. A
mast top 1100 is shown having an oval mast 1102 with rotating
sleeve wrap 1120, sail track 1115 and sail head 1114. A typical
halyard 1106 and halyard sheave is shown at 1104. Two brackets are
attached to each side sail head shown at 1110 and 1110A, with one
attachment point at 1112. Brackets 1110 and 1110A are spaced apart
at their top most portion. Attached to the top of these brackets
1110 is a shaft or tube 1108, running perpendicular to sail top
1114 as shown. H
[0075] End of halyard 1106 is attached loosely to shaft or tube
1108 so that a reasonable rotation of sleeve 1120 and sail head
1114 is possible to achieve high aerodynamic efficiency of the
mainsail. It is even more important for maximum aerodynamic
efficiency that the tack of a mainsail according to the present
invention is not fixed.
[0076] FIG. 12 shows 1200, being a part section of a mast 1202 and
boom 1218 of a traditional yacht. Also shown is a rotating sleeve
wrap 1204, sail track 1206 and sail bottom 1210 with tack eyelet
1208. A gooseneck assembly is shown at 1230. Attached to boom are
two brackets, shown at 1214 and 1214A. Attached to top of brackets
1214 and 1214A is a shaft or tube 1212 perpendicular to boom 1218.
Bottom of brackets 1214 and 1214A are attached to boom 1218
tightly, or so as to allow bracket to pivot. A second tube or shaft
1215 could alternatively be used through boom 1218 attached to
bottom of brackets 1214 so as to allow tubes and brackets to move
side to side shown by arrow 1220. Note brackets 1214 could also be
soft and flexible connectors.
[0077] It would also be possible to connect ends of rod or tube
1212 to lines shown dashed at 1224 and 1224A directly to base of
mast 1202. (these lines one shown dotted at 1221 could also pass
through brackets on each side of boom shown at one at point 1216).
An alternative would be to connect lines 1224 and 1224A to a single
line 1228, passing through mast base block 1226, so as to be able
to adjust tension in lines 1224 and shaft or tube 1212. Note tack
hole 1208 is larger than rod or tube 1212 so that tack is able to
slide sideways along rod or tube 1212. In this way, sail tack 1208
is able to slide side to side along rod 1212 allowing sleeve 1204
tack 1208 and sail track 1206 to rotate in order for foot of sail
1210 shown by dashed lines, to achieve the maximum aerodynamic
efficiency.
[0078] FIG. 13 shows 1280 being view of a partial mast 1252 and
boom 1273 detailing how a rotating sleeve wrap according to the
present invention can be applied to a mainsail boom furling
system.
[0079] Mast 1252 has section of fairing wrap 1254 with partial sail
track 1256 and part sail 1258, together with traditional boom 1273
connected to mast with traditional gooseneck assembly 1279. A
mainsail boom furling tube 1264 has a manual turning sheave 1259
which with a line, not shown can be used to furl mainsail. Furling
tube 1264 is held at each end by brackets 1262 and 1268, through
which shafts 1276 and 1266 pass. These shafts can pass through
spherical ball joints within housing brackets 1262 and 1268, or as
shown, could have pivoting housings 1260 and 1272 pivoting on
housing brackets 1262 and 1268. Shaft 1266 is able to slide in
housing (or spherical bearing).
[0080] Bracket 1268 is fastened to boom 1273 as shown. Two
brackets, one visible at 1278, holds a cross rod or tube 1276 on
which housing 1262 slides, shown by arrow 1275. In this way, sleeve
wrap 1254 together with sail track and sail 1258 is able to rotate
around mast 1252 to allow a highly efficient aero foil shape to be
produced on the lee side of the mast at the lowest portion of the
mainsail, thereby producing maximum drive from the foot of the
sail, if a skirt is employed to eliminate the otherwise lost drive
from under the boom.
[0081] FIG. 14 shows another method of attachment of a mainsail
tack allowing rotation of the sleeve wrap and sail according to the
present invention. Part sail tack and boom detail 1400 shows a
mainsail corner 1410 with tack eyelet 1406. Eyelet connects to a
forward pointing right angled rod or tube 1414 via a shackle or
rope loop 1408. Note a loop sewn to sail would also be possible.
Vertical shaft portion of rod or tube 1414 passes loosely through
vertical hole 1415 of boom portion 1412. End of rod or tube 1414
could be terminated under boom 1412 at 1416, or be attached to a
tensioning line similar to line 1228 of FIG. 12. Rod or tube 1414
could also be housed in gooseneck vertical pivot hole shown by
centerline 1418 or position 1418A and point rearwards. Right angled
rod or tube 1414, could terminate under gooseneck or be attached to
a line for vertical adjustment. In this way, mast wrap 1401, sail
track 1404 and sail corner 1410 is able to rotate, via rotation of
right angled shaft or tube 1414 shown by arrow 1417 as required to
achieve the maximum aerodynamic efficiency at the back of the mast
at the foot of the mainsail according to the present invention.
Note, loop or shackle 1408 would slide along rod or tube 1414
during the rotation of rod or tube 1414.
[0082] FIG. 15 shows a partial cross section 1500 of a mast segment
1502 and a sail track 1516 which is connected to a flexible wrap
around mast 1502 the ends of which are shown at 1504 and 1520,
attached to sail track 1516 at 1805 and 1518. Spaced multiple
elongate cars or slugs are shown cross sectioned at 1514 are
connected to multiple elongate spaced members shown shaded at 1508,
via loose rivets or bolts shown at 1512, such that when sail is
lowered, members 1508 are able to rotate to approximately the
horizontal position for flaking. Mainsail portion 1506 is connected
to spaced members 1508, by any means, one of which being wrapped
around members 1508. At 1510. Member segments or padding can be
used between spaced slugs or cars 1810 to avoid a large gap between
short elongate members 1508, in order that minimal air from the
windward side leaks into the lee side of the sail. Note, wrap
1504/1520 may be short and separate bands, or run the length of the
track 1516.
[0083] In this way car type slides may be used, which gives better
control of the sail when lowering, while still providing a good
airfoil connection on the lee side of the sail to mast, in order to
give maximum aerodynamic efficiency and drive and eliminate the
majority of the approximately forty percent loss of the normal car
type mainsail to mast connection. The above show means to
significantly increase the efficiency and drive of a mainsail while
at the same time allowing for a smaller sail with a reduced center
of effort producing less heel and much easier sail and boat
handling in strong winds. The arrangements detailed would also
significantly reduce drag and weight of a yacht. It should be noted
that the foregoing improvements or details of one arrangement may
be, where appropriate, applied to any of the other
arrangements.
[0084] It should be noted that although mainsails are the
predominant form of mast sail combination, the above disclosure
applies equally to other mast sail combinations such as mizzenmasts
and sails.
* * * * *