U.S. patent application number 13/315696 was filed with the patent office on 2013-06-13 for wakesurfing boat and hull for a wakesurfing boat.
This patent application is currently assigned to 3MADMEN. The applicant listed for this patent is Yann Le Jeune, Pietro Lagioia, Arye Laniado, Joshua Laniado, Albert VIVIANI. Invention is credited to Yann Le Jeune, Pietro Lagioia, Arye Laniado, Joshua Laniado, Albert VIVIANI.
Application Number | 20130145978 13/315696 |
Document ID | / |
Family ID | 47520696 |
Filed Date | 2013-06-13 |
United States Patent
Application |
20130145978 |
Kind Code |
A1 |
VIVIANI; Albert ; et
al. |
June 13, 2013 |
WAKESURFING BOAT AND HULL FOR A WAKESURFING BOAT
Abstract
A wakesurfing boat includes a hull. A bottom of the hull defines
a W-shape in cross-section, the W-shape including a central
inverted V-shaped portion. A ballast system includes a plurality of
sets of ballast tanks. The boat has a plurality of modes: a
cruising mode with ballast tanks empty, a first portion of the
bottom in contact with the water, a stern-down trim .theta..sub.1;
a ballasted static mode with ballast tanks filled with ballast
water, the hull displacing more water, a larger portion of the
bottom in contact with the water, a bow-down trim .theta..sub.2;
and a dynamic surfing mode with ballast tanks filled with ballast
water, an intermediate portion of the bottom in contact with the
water, and an intermediate trim .theta..sub.3. A wake wave,
generated in the dynamic surfing mode is larger than a wake wave
generated in the cruising mode.
Inventors: |
VIVIANI; Albert; (US)
; Laniado; Arye; (US) ; Laniado; Joshua;
(US) ; Jeune; Yann Le; (Villefranche sur Mer,
FR) ; Lagioia; Pietro; (Bari, IT) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
VIVIANI; Albert
Laniado; Arye
Laniado; Joshua
Jeune; Yann Le
Lagioia; Pietro |
Villefranche sur Mer
Bari |
|
US
US
US
FR
IT |
|
|
Assignee: |
3MADMEN
|
Family ID: |
47520696 |
Appl. No.: |
13/315696 |
Filed: |
December 9, 2011 |
Current U.S.
Class: |
114/271 ;
114/56.1; 114/61.26; 114/61.33; 440/49 |
Current CPC
Class: |
B63B 2001/201 20130101;
B63B 34/70 20200201; B63B 43/06 20130101; B63B 2207/02
20130101 |
Class at
Publication: |
114/271 ;
114/56.1; 114/61.33; 114/61.26; 440/49 |
International
Class: |
B63B 1/04 20060101
B63B001/04; B63H 1/14 20060101 B63H001/14 |
Claims
1. A wakesurfing boat operable in a body of water, comprising: a
hull comprising a bow, a stern, a port bulwark, a starboard
bulwark, a bottom, a length L, and a beam B; and a ballast system
supported by the hull, the ballast system comprising a plurality of
ballast tanks, configured to alternatively and selectively receive
and discharge ballast water, in order to trim the hull, in one of a
plurality of modes, including: (i) a cruising mode, wherein the
ballast tanks are substantially empty, the hull is moving through
the body of water, the hull has at least a first weight, displacing
at least a first amount of displaced water corresponding to the
first weight, and a first portion of the hull bottom is in contact
with the body of water; (ii) a ballasted static mode, wherein the
ballast tanks are filled or at least partially filled with ballast
water, the hull is static in the body of water, the hull has at
least a second weight greater than the first weight, displacing at
least a second amount of displaced water corresponding to the
second weight, the second amount of displaced water being greater
than the first amount of displaced water, and a second portion of
the hull bottom is in contact with the body of water, the second
portion being greater than the first portion; and (iii) a dynamic
surfing mode, wherein the ballast tanks are filled or at least
partially filled with ballast water, the hull is moving through the
body of water, the hull has at least the second weight, displacing
at least the second amount of displaced water, and a third portion
of the hull bottom is in contact with the body of water, the third
portion being intermediate the first portion and the second
portion; wherein in the cruising mode, the hull has a first trim
.theta..sub.1 down by the stern; wherein in the ballasted static
mode, the hull has a second trim .theta..sub.2 down by the bow; and
wherein in the dynamic surfing mode, the hull has a third trim
.theta..sub.3 intermediate the first trim and the second trim.
2. The wakesurfing boat of claim 1, wherein the bottom is
configured as a central inverted V in cross-section, with the
central inverted V commencing at the bow and extending to the
stern.
3. The wakesurfing boat of claim 2, wherein the central inverted V
defines a plurality of apex angles .alpha..sub.1 . . .
.alpha..sub.n at preselected positions extending from the bow to
the stern.
4. The wakesurfing boat of claim 1, wherein a length to beam ratio
(L/B) of the hull is less than or equal to 3.0.
5. The wakesurfing boat of claim 1, wherein the ballast tanks
comprise a plurality of sets of dual tanks, each of the ballast
tanks of each set being positioned on the hull at generally
symmetrical locations with respect to one another.
6. The wakesurfing boat of claim 5, wherein the sets of dual tanks
are configured such that, when selected tanks are filled or at
least partially filled with the ballast water in the dynamic
surfing mode, the hull is trimmed with a plurality of trim angles
.theta..sub.4 . . . .theta..sub.n.
7. The wakesurfing boat of claim 1, wherein the hull bottom extends
from the starboard bulwark to the port bulwark, and from the bow to
the stern, the bottom in its entirety being configured as a W in
cross-section, including port and starboard nadirs, and a central
apex, wherein the central apex of the W defines a central inverted
V, the central inverted V extending from the bow to the stern.
8. The wakesurfing boat of claim 1, wherein when the hull operates
in the body of water in the cruising mode, it generates at least
one wake W.sub.1 having a first wake height W.sub.h1.
9. The wakesurfing boat of claim 8, wherein when the hull operates
in the body of water in the dynamic surfing mode, it generates at
least one wake wave W.sub.2 having a second wake wave height
W.sub.h2 that is greater than the first wake height W.sub.h1.
10. The wakesurfing boat of claim 1, wherein the hull is
self-propelled.
11. The wakesurfing boat of claim 10, further comprising a pair of
inward-rotating propellers.
12. A hull for a wakesurfing boat, comprising: a bow; a stern; port
and starboard bulwarks; a length L and a beam B; a bottom extending
from the bow to the stern, and from the port bulwark to the
starboard bulwark, the bottom in its entirety being configured
substantially as a W in cross-section, including port and starboard
nadirs and a central apex, wherein the central apex defines a
central inverted V portion extending from the bow to the stern, the
central inverted V portion having an apex angle .alpha. changing at
preselected positions between the bow and the stern; and a trim and
displacement altering system selectively altering a trim and an
amount of water displaced by the hull, including a plurality of
ballast tanks and ballast water, thereby providing the hull with a
plurality of modes, including: (i) a cruising mode, with the hull
moving through the body of water, the ballast tanks substantially
empty, displacing at least a first amount of displaced water, a
first portion of the bottom being in contact with a body of water,
and creating at least one first wake W.sub.1 in the body of water,
the first wake having a first wake height W.sub.h1; (ii) a
ballasted static mode, with the hull static in the body of water,
the ballast tanks filled or at least partially filled with ballast
water, displacing at least a second amount of displaced water
greater than the first amount of displaced water, and having a
second portion of the bottom in contact with the body of water, the
second portion being greater than the first portion; and (iii) a
dynamic surfing mode, with the hull moving through the body of
water, the ballast tanks filled or at least partially filled with
ballast water, displacing at least the second amount of displaced
water, a third portion of the bottom in contact with the body of
water, the third portion being intermediate the first portion and
the second portion; and creating at least one second wake wave
W.sub.2 in the body of water, the second wake wave having a second
wave height W.sub.h2. wherein in the cruising mode, the hull has a
first trim .theta..sub.1 down by the stern; wherein in a ballasted
static mode, the hull has a second trim .theta..sub.2 down by the
bow; and wherein in the dynamic surfing mode, the hull has a third
trim .theta..sub.3 intermediate the first trim and the second
trim.
13. The hull of claim 12, wherein the plurality of ballast tanks
are configured to be, alternately and selectively, substantially
empty of, filled with, or partially filled with, the ballast
water.
14. The hull of claim 12, wherein the hull is a planing hull.
15. The hull of claim 12, wherein a length of the hull is in a
range from approximately 20 feet to approximately 60 feet.
16. The hull of claim 15, wherein the length of the hull is
selected from the group consisting of 20 feet, 28 feet, 35 feet, 43
feet, and 60 feet.
17. The hull of claim 12, further comprising a transom and a pair
of inward-rotating propellers.
18. The hull of claim 12, wherein the second wake wave height
W.sub.h2 is greater than the first wake height W.sub.h1.
19. The hull of claim 19, wherein the second wake wave height
W.sub.h2 is approximately 0.5 meters to approximately 2.7
meters.
20. The hull of claim 12, wherein a length to beam ratio L/B is
less than or equal to 3.0.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to boats and boat hulls. More
particularly, the present invention relates to wakesurfing boats,
and hulls used for wakesurfing boats.
BACKGROUND OF THE INVENTION
[0002] Wakesurfing is a watersport that is growing in popularity. A
wakesurfer, initially being towed behind a boat via a tow rope,
rises to his feet on a surf board in a body of water, (e.g., an
ocean, a sea, a lake, or a river) similar to a waterskier or a
wakeboarder. Ideally, the boat should generate in its wake a wave
that mimics a size, a shape, and a duration of an ocean wave. If
the wake wave reaches a sufficient size, the wakesurfer, unlike a
waterskier or a wakeboarder, releases the tow rope, and rides the
board on a crest and/or a face of the wake wave, traversing back
and forth on the wake wave face as desired, similar to an ocean
surfer.
[0003] Until now, wakesurfers have been attempting to surf
primarily in the wakes of existing cruising boats, waterskiing
boats and wakeboarding boats. These classes of boats typically are
designed for speed, seaworthiness, and handling characteristics. A
problem with attempting to wakesurf behind traditional cruising
boats, waterskiing boats, and wakeboarding boats, however, is that
such boats fail to generate sufficiently large, sufficiently
well-shaped, and sufficiently long-lasting wake waves to give the
wakesurfer a long, satisfying ride.
[0004] As is well known in the field of fluid dynamics, a boat,
when passing through a body of water, creates separate waves that
move in the boat's wake. In general, separate wake waves originate,
respectively, from the boat's bow, centerline, quarter, and stern.
Each wake wave generally forms the arms of a V, with the source of
the respective wake wave being at the point of the V (the boat),
and transverse curled wave crests forming offset from the path of
the boat. Wake wave height (W.sub.h) is a function of several
factors, including for example a speed of the boat hull in the body
of water, resistance to the boat hull as it moves through the body
of water, Froude number, a shape of the hull, a length of the hull,
a length/beam ratio (L/B) of the hull, a speed/length ratio (SLR)
of the hull, an amount of the boat hull bottom in contact with the
body of water, and an amount of water displaced by the boat as it
moves through the body of water. Cruising boats, wakeboarding
boats, and waterskiing boats typically are configured with planing
hulls, L/B=4.0-7.0, light displacements, minimal hull resistance
when moving through the body of water, and optimal seaworthiness
and handling characteristics.
[0005] A self-propelled wakesurfing boat, and a hull for a
wakesurfing boat, are desired which will generate the largest,
best-shaped and longest-lasting wake waves possible in view of the
boat's size, displacement, and speed.
SUMMARY OF THE INVENTION
[0006] Accordingly, the present invention is directed to a
wakesurfing boat for wakesurfing in a body of water, and a hull for
a wakesurfing boat, that substantially obviates one or more of the
problems caused by the limitations and disadvantages of the related
art.
[0007] A wakesurfing boat operable in a body of water in accordance
with the present invention includes a hull. The hull includes a
bow, a stern, a port bulwark, a starboard bulwark, a bottom, a
length (L), and a beam (B).
[0008] A trim-altering ballast system is supported by the hull. The
trim-altering ballast system includes a plurality of ballast tanks,
configured to alternately and selectively receive and discharge
ballast water, in order to trim the hull, in one of a plurality of
modes, including:
[0009] (i) a cruising mode, wherein the hull is moving through the
body of water, the ballast tanks are substantially empty, the hull
has at least a first weight, thereby displacing at least a first
amount of water, and a first portion of the hull bottom is in
contact with the body of water,
[0010] (ii) a ballasted static mode, wherein the hull is static in
the body of water, the ballast tanks are filled or at least
partially filled with ballast water, the hull has at least a second
weight, displacing at least a second amount of water corresponding
to the second weight, the second amount of displaced water being
greater than the first amount of displaced water, and a second
portion of the hull bottom is in contact with the body of water,
the second portion of the hull bottom being greater than the first
portion of the hull bottom,
[0011] (iii) a dynamic surfing mode, wherein the hull is moving
through the body of water, the ballast tanks are filled or at least
partially filled with ballast water, the hull has at least the
second weight, displacing at least the second amount of displaced
water, and a third portion of the hull bottom is in contact with
the body of water, the third portion of the hull bottom being
intermediate the first portion and the second portion.
[0012] In the cruising mode, the hull has a first trim
.theta..sub.1, down by the stern.
[0013] In the ballasted static mode, the hull has a second trim
.theta..sub.2 down by the bow.
[0014] In the dynamic surfing mode, the hull has a third trim
.theta..sub.3, intermediate the first trim .theta..sub.1 of the
cruising mode and the second trim .theta..sub.2 of the ballasted
static mode.
[0015] Preferably, the ballast tanks comprise a plurality of sets
of dual tanks, each set of dual tanks being positioned at generally
symmetrical locations with respect to one another along the length
of the hull.
[0016] In the dynamic surfing mode, separate ballast tanks can be
selectively filled, or partially filled, with ballast water, to
vary the weight and displacement of the hull, and to trim the hull
with a plurality of alternate trim angles .theta..sub.4 . . .
.theta..sub.n.
[0017] In accordance with the invention, the bottom of the hull is
configured in part as a central inverted V in cross-section, with
the central inverted V commencing at the bow and extending to the
stern. An apex angle .alpha. of the central inverted V changes at
preselected positions as the inverted V extends from the bow to the
stern, i.e., .alpha..sub.1 . . . .alpha..sub.n. More specifically,
the entire bottom is configured substantially as a W in
cross-section, wherein the W extends from the port bulwark to the
starboard bulwark. The W includes port and starboard nadirs and a
central apex, wherein the central apex of the W defines the central
inverted V.
[0018] In accordance with the invention, the central inverted V
defines a funnel through which water passes when the hull moves
through the body of water. More water passes through the funnel in
the dynamic surfing mode than in the cruising mode.
[0019] In accordance with the invention, as the hull moves through
the body of water in the dynamic surfing mode, the combination of
the ballast tanks being filled or partially filled with ballast
water, the at least second weight and the corresponding at least
second displacement, the third portion of the V-shaped hull bottom
being in contact with the body of water, the hull being in the
third trim .theta..sub.3, and the increased amount of water passing
through the funnel defined by the central inverted V, results in an
increase in resistance to the hull.
[0020] In accordance with the invention, when the hull moves
through the body of water in the cruising mode, with relatively
minor resistance to the hull, it generates at least one wake,
W.sub.1 having a first wake height, W.sub.h1. When the hull moves
through the body of water in the dynamic surfing mode, however,
with the increased water resistance to the hull, it generates at
least one wake wave W.sub.2 having a second wake wave height
W.sub.h2. The second wake wave height W.sub.h2 of the at least one
wake wave W.sub.2 is greater than the first wake height W.sub.h1 of
the at least one wake W.sub.1.
[0021] Preferably, the second wake wave height W.sub.h2 of the at
least one wake wave W.sub.2 is approximately 0.5 meters to
approximately 2.7 meters, depending on the length of the hull.
[0022] A plurality of hull lengths are within the scope of the
invention, e.g., 20 feet-60 feet, including but not limited to a 43
foot yacht, a 35 foot cruiser, and a 28 foot sport boat. Regardless
of the hull length selected, the beam is selected such that the
length to beam ratio (L/B) of the hull is less than or equal to
3.0, i.e., L/B.ltoreq.3.0.
[0023] In accordance with the invention, the boat hull is
self-propelled, preferably by two inward-rotating propellers.
[0024] In another aspect of the invention a hull for a wakesurfing
boat operable in a body of water includes a bow, a stern, a port
bulwark, a starboard bulwark, and a bottom extending between the
bow and the stern, and from the port bulwark to the starboard
bulwark, wherein the entire bottom is configured substantially as a
W in cross-section, the W extending from the port bulwark to the
starboard bulwark, including a port nadir, a starboard nadir, and a
central apex, the central apex defining a central inverted V
portion extending from the bow to the stern; and a trim and
displacement altering apparatus, comprising a plurality of ballast
tanks, selectively altering a trim, an amount of the hull bottom in
contact with the body of water, and an amount of displaced water
displaced by the hull, thereby providing the hull with a plurality
of modes, including:
[0025] (i) a cruising mode, wherein the hull is moving through the
body of water, the ballast tanks are substantially empty, the hull
displaces at least a first amount of displaced water, a first
portion of the hull bottom is in contact with the body of water,
and the hull has a first trim .theta..sub.1 down by the stern.
[0026] (ii) a ballasted static mode, wherein the hull is static in
the body of water, the ballast tanks are filled or at least
partially filled with ballast water, the hull displaces at least a
second amount of displaced water greater than the first amount of
displaced water, a second portion of the hull bottom is in contact
with the body of water, the second portion being greater than the
first portion, and the hull has a second trim .theta..sub.2 down by
the bow;
[0027] (iii) a dynamic surfing mode, wherein the hull is moving
through the body of water, the ballast tanks are filled or at least
partially filled with ballast water, the hull displaces at least
the second amount of displaced water, a third portion of the hull
bottom is in contact with the body of water, the third portion
being intermediate the first portion and the second portion, and
the hull has a third trim .theta..sub.3 intermediate the first trim
.theta..sub.1 and the second trim .theta..sub.2.
[0028] In the cruising mode, the hull creates at least one first
wake W.sub.1, having a first wake height W.sub.h1. W.sub.h1 Is
approximately 10-15 cm.
[0029] In the dynamic surfing mode, the hull creates at least one
second wake wave W.sub.2, having a second wake wave height
W.sub.h2, which is greater than W.sub.h1. W.sub.h2 is approximately
0.5 meters to approximately 2.7 meters, depending on the length of
the hull.
[0030] It is to be understood that both the foregoing general
description and the following detailed description are exemplary
and explanatory, and are intended to provide further explanation of
the invention as claimed.
[0031] The accompanying drawings are included to provide a further
understanding of the invention, and are incorporated in and
constitute a part of the specification, illustrate the presently
preferred embodiment of the invention, and together with the
description, serve to explain the principles of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 is a side view of a wakesurfing boat in accordance
with the invention;
[0033] FIG. 2 is a side view of a 43 foot hull of a wakesurfing
boat in accordance with the invention, with numbered
cross-sectional lines drawn at preselected locations between a bow
and a stern of the hull;
[0034] FIG. 3 is a bottom view of the hull of FIG. 2, with the
numbered cross-sectional lines drawn at the same preselected
locations between the bow and the stern of the hull, as depicted in
FIG. 2;
[0035] FIGS. 4A-4N are longitudinal cross-sectional views of the
hull, viewed from the stern, the cross-sections taken along each
numbered cross-sectional line on the side and bottom of the hull
depicted in FIGS. 2 and 3, showing an apex angle .alpha. of a
central inverted V in a center of the hull bottom;
[0036] FIG. 5 is a view of the bottom of the hull depicted in FIG.
2;
[0037] FIG. 6 is a view from the bow of the hull depicted in FIG.
5;
[0038] FIG. 7 is a view from the stern of the hull depicted in FIG.
5;
[0039] FIG. 8 is a view from the bottom of the hull in accordance
with the invention, while the hull is in motion through a body of
water, depicting a flow of water moving into and through a funnel
defined by the central inverted V-shaped bottom of the hull;
[0040] FIG. 9 is a view of the hull depicting locations of the sets
of ballast tanks in a trim-altering ballast system, in accordance
with the invention;
[0041] FIG. 10 is a side cross-sectional view of a hull in
accordance with the invention in a Lightship condition, with the
ballast tanks empty;
[0042] FIG. 11 is a side cross-sectional view of a hull in
accordance with the invention, with the ballast tanks 50% filled
with ballast water;
[0043] FIG. 12 is a side cross-sectional view of a hull in
accordance with the invention, with the ballast tanks 100% filled
with ballast water;
[0044] FIG. 13 is a graph depicting draft versus displacement for a
43 foot hull in accordance with the present invention;
[0045] FIG. 14 is a side view of a prior art power boat in motion
in a body of water;
[0046] FIG. 15 is a side cross-sectional view of a 43 foot hull in
accordance with the invention, with ballast tanks empty, operating
in a cruising mode;
[0047] FIG. 16 is a side cross-sectional view of a 43 foot hull in
accordance with the invention, with the ballast tanks 100% filled,
in a ballasted static mode;
[0048] FIG. 17 is a side cross-sectional view of a 43 foot hull in
accordance with the invention, with the ballast tanks 100% filled,
operating in a dynamic surfing mode;
[0049] FIG. 18 is a side cross-sectional view of a 43 foot hull in
accordance with the invention, with the ballast tanks 50% filled,
operating in the dynamic surfing mode;
[0050] FIG. 19 is a graph depicting expected wake wave height
versus hull length, determined via extrapolation, for a hull in the
dynamic surfing mode in accordance with the invention;
[0051] FIGS. 20A-20C are drawn-to-scale cross-sectional views of a
20 foot hull in accordance with the invention;
[0052] FIGS. 21A-21C are drawn-to-scale cross-sectional views of a
28 foot hull in accordance with the invention;
[0053] FIGS. 22A-22C are drawn-to-scale cross-sectional views of a
35 foot hull in accordance with the invention;
[0054] FIGS. 23A-23C are drawn-to-scale cross-sectional views of a
60 foot hull in accordance with the invention;
[0055] FIG. 24 is a chart depicting changes in static dimensions of
the hull, including (in order): length at the waterline, beam at
the waterline, immersed volume, displacement, length at the center
of buoyancy, Block coefficient, amidship transversal section
immersed area, amidship transversal section coefficient, waterplane
area, length at the center of flotation, prismatic coefficient, and
immersed hull surface, for a 43 foot hull at varying drafts (i.e.,
"immersione"), from 0.46 meters to 0.74 meters, measured in 0.02
meter increments;
[0056] FIG. 25 is a graph depicting wake wave height versus
distance from the boat's transom, for a boat in accordance with the
invention, while operating in the dynamic surfing mode;
[0057] FIG. 26 is a graph depicting waves in the wake of the boat
while operating in the dynamic surfing mode in accordance with the
invention;
[0058] FIG. 27 is a graph depicting wave height versus distance
from a centerline of the boat and distance from a transom, while
operating in the dynamic surfing mode in accordance with the
invention; and
[0059] FIG. 28 is a view of the stern of the boat in accordance
with the invention, depicting the transom and inward-rotating
propellers.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0060] Reference will now be made in detail to the presently
preferred embodiments of the invention, examples of which are
illustrated in the accompanying drawings.
[0061] A presently preferred embodiment of a wakesurfing boat in
accordance with the present invention is shown in FIG. 1 and is
designated generally by reference numeral 10.
[0062] As broadly embodied herein and referring to FIG. 1, the
wakesurfing boat 10 includes a hull 12.
[0063] Referring to FIGS. 1-3, hull 12 includes a bow 14, a stern
16, a port bulwark 18, a starboard bulwark 20, a length L, and a
beam B.
[0064] Preferably, hull 12 is a planing hull. Different hull
lengths are possible and within the broad scope of the invention,
including, without limitation, a 43 foot yacht, a 35 foot cruiser,
and a 28 foot sport boat. Other hull lengths also are within the
scope of the invention e.g., 20 feet through 60 feet. In accordance
with the invention, regardless of the boat length L selected, a
maximum beam B always is selected such that the length to beam
ratio L/B of the respective hull 12 is less than or equal to 3.0,
i.e., L/B.ltoreq.3.0.
[0065] As further broadly embodied herein, with reference to FIGS.
2-7, the hull 12 includes a bottom 22. Bottom 22 extends from the
bow 14 to the stern 16, and from the port bulwark 18 to the
starboard bulwark 20. Bottom 22 preferably is configured, when
viewed longitudinally, in cross-section, substantially in a
W-shape, with a central inverted V-shaped portion 26 extending from
the bow 14 to the stern 16. Referring to FIGS. 4A-4N, the inverted
V-shaped portion 26 has an apex angle .alpha., which differs at
selected locations .alpha..sub.1 . . . .alpha..sub.n along the
length L of the hull. The apex angles .alpha..sub.1 . . .
.alpha..sub.n are depicted in FIGS. 4A-4N as .alpha..sub.1 . . .
.alpha..sub.14, with a cross-sectional cut taken at regular
intervals along the length L of the hull, extending between the bow
14 and the stern 16. Preferably, the apex angles .alpha. vary from
.alpha..sub.1, approximately 178.degree., proximate the bow 14, as
shown in FIG. 4A, through a sequence of steeper and shallower apex
angles .alpha..sub.2 . . . .alpha..sub.14, e.g., .alpha..sub.7,
approximately 152.degree., proximate a point roughly amidships, as
shown in FIG. 4G, to .alpha..sub.14, approximately 179.degree.,
proximate the stern 16, as shown in FIG. 4N.
[0066] To port and starboard of the central inverted V-shaped
portion 26, the bottom 22 further includes an inclined portion 30
on the port side of the hull, and an inclined portion 32 on the
starboard side of the hull, connecting the central inverted
V-shaped portion 26 to the port and starboard bulwarks 18 and 20,
respectively, thereby defining the substantial cross-sectional W
shape of the bottom 22. The W shape forms the entire bottom 22 of
the hull 12, from the port bulwark 18 to the starboard bulwark 20.
The W shape, defined by the inclined portions 30 and 32, and the
central V-shaped portion 26 further includes a port nadir 24 at the
bottom of the inclined portion 30, a starboard nadir 25 at the
bottom of the inclined portion 32, and a central apex 27 at the
inverted peak of the V-shaped portion 26.
[0067] The central inverted V-shaped portion 26 defines a funnel
28. As depicted in FIG. 8, when the hull 12 moves through a body of
water, agitating a surface microlayer thereof, water is deflected
by the nadirs 24 and 25 of the W-shaped bottom into and through the
funnel 28 defined by the V-shaped portion 26. Water exiting the
funnel 28 at the stern of the boat will help define wake waves.
[0068] As broadly embodied herein, the wakesurfing boat 10 further
includes a trim and displacement-altering ballast system 34,
supported within the hull 12. Referring to FIG. 9, the system 34
includes a plurality of dual sets of ballast tanks 36a/36b,
37a/37b, and 38a/38b, positioned at selected symmetrical positions
along the length of hull 12. As embodied in FIG. 9, a first set of
dual ballast tanks 36a/36b are positioned proximate the port and
starboard bulwarks 18 and 20, respectively, and are the farthest
forward of all of the sets of ballast tanks. As further embodied in
FIG. 9, a second set of dual ballast tanks 37a/37b are positioned
proximate the port and starboard bulwarks 18 and 20, respectively
aft of ballast tanks 36a/36b, and approximately amidships. As
further embodied in FIG. 9, a third set of dual ballast tanks
38a/38b are positioned proximate the port and starboard bulwarks 18
and 20, respectively, proximate the stern 16 of the hull 12. The
different sets of ballast tanks have different volumes, and
accordingly, when filled or partially filled with ballast water,
have different weights, correspondingly displacing different
amounts of water beneath the hull, as roughly set forth in the
chart below, with tolerances of approximately 10%, as would be
understood by one of ordinary skill in the art of naval
architecture:
TABLE-US-00001 Ballast Tanks 36a/36b 37a/37b 38a/38b Individual
1,295 liters/tank 1,965 liters/tank 1,330 liters/tank Tank Volume
Combined 2,590 liters 3,930 liters 2,260 liters Ballast Tank Volume
Total Ballast 9,180 liters Total Weight 22,629 Kg
[0069] The approximate total weight (ballast+weight of the
half-loaded boat) listed above is calculated taking into
consideration the presence of frames, structures and valves in the
ballast tanks, which take up approximately 6% of the volume of each
tank, (approximately 100 liters/ballast tank), i.e., 9,180
liters-0.060 (9,180 liters)=8,629 liters.times.1,000 kg/m.sup.3
(i.e., density of fresh water)=8,629 Kg+14,000 Kg (i.e., weight of
the half-loaded boat)=22,629 Kg. As noted, the density of fresh
water, (i.e., 1,000 kg/m.sup.3) was used in this calculation. A
person of ordinary skill in the art will recognize that the results
of this calculation will differ if the density of salt water (i.e.,
1,025 kg/m.sup.3-1,035 kg/m.sup.3) is used in the calculation. The
wakesurfing boat of the invention is buoyant and operable both in
fresh water and in salt water.
[0070] Since, under Archimedes Principle, a weight of the hull 12
corresponds to a weight of water displaced by the hull 12, a
ballast tank-empty (i.e., "Lightship") displacement, M.sub.LCC, of
the half-loaded hull 12=14,000 Kg.
[0071] As shown above, a ballast tank-filled displacement,
M.sub.LDC, of the half-loaded hull 12=22,629 Kg.
[0072] As broadly embodied in FIG. 10, when the hull 12 is in the
Lightship condition, with the ballast tanks empty, water rises on
the hull to a first waterline WL.sub.1.
[0073] As broadly embodied in FIG. 11, when the ballast tanks are
50% filled, the water rises to a second waterline WL.sub.2.
[0074] As broadly embodied in FIG. 12, when the ballast tanks are
100% filled, the water rises to a third waterline WL.sub.3.
[0075] FIG. 13 graphically depicts drafts for various displacements
of the hull 12 in accordance with the invention.
[0076] FIG. 14 broadly depicts a traditional power boat, such as a
traditional waterskiing boat, cruiser, or sport boat, moving
through a body of water.
[0077] The hull 12 in accordance with the invention, with ballast
tanks empty or nearly empty, cruising through a body of water in a
"cruising" mode, is depicted in FIG. 15. The resistance of the
water against the planing hull lifts the bow 14 up, correspondingly
pushing the stern 16 down, so that the hull 12 is a trimmed stern
down with a first trim angle .theta..sub.1. In this operating mode,
only a relatively small first portion 52 of the hull bottom 22
contacts the body of water. In addition, a first amount of water is
forced through the funnel 28 defined by the inverted V-shaped
bottom 12. With these parameters, the water provides a relatively
minor first amount of resistance to the hull, as the hull passes
through the body of water.
[0078] FIG. 16 depicts the hull 12 in accordance with the
invention, with ballast tanks 100% filled with ballast water,
sitting static in the water in a ballasted static mode. A second
portion 53 of hull bottom 22 is in contact with the body of water.
Because of the greater weight added by the ballast water, the hull
12 squats lower in the water. For this reason, the second portion
53 of the hull bottom is greater than first portion 52 of the hull
bottom when the hull 12 is operating in the cruising mode. Also, in
this ballasted static mode, the hull is trimmed bow down, with a
second trim .theta..sub.2.
[0079] FIG. 17 depicts the hull 12 in accordance with the
invention, with the ballast tanks 100% filled with ballast water,
and the hull 12 moving through the body of water in a dynamic
surfing mode. This is the operating mode intended for the surfer to
wakesurf, in accordance with the invention. The bow 14 of the hull
12 is pushed partially upward by force of the water, but due to the
increased weight of the ballast water in the filled or at least
partially-filled ballast tanks, the bow 14 is not pushed upward as
high as it is in the cruising mode. The hull 12, therefore, is
trimmed in an intermediate third trim .theta..sub.3, intermediate
the stern-down trim .theta..sub.1 of the cruising mode and the
bow-down trim .theta..sub.2 of the ballasted static mode. Moreover,
the extra ballast water in the ballast tanks, causing the hull 12
to squat lower in the water, combined with the lower bow 14
associated with the intermediate trim .theta..sub.3, results in a
third portion 54 of the W-shaped hull bottom 22 being in contact
with the body of water. The third portion 54 of the W-shaped hull
bottom 12 is intermediate the first portion 52 of the hull bottom
22 contacting the body of water in the cruising mode, and the
second portion 53 of the W-shaped hull bottom 22 contacting the
body of water in the ballasted static mode, i.e., more of the
W-shaped bottom 22 is in contact with the body of water in dynamic
surfing mode than it is in the cruising mode. In addition, in the
dynamic surfing mode, a second larger amount of water is forced
through the funnel 28 defined by the inverted V-shaped bottom 12.
The combination of the increased weight due to the ballast water,
the resultant increased displacement, the increased third portion
54 of the W-shaped bottom 12 being in contact with the water, the
intermediate trim .theta..sub.3, and the increased amount of water
passing through the funnel 28 are parameters which increase
resistance to the hull 12 as it passes through the body of
water.
[0080] Moreover, when the hull 12 moves through the body of water
in the cruising mode, with the ballast tanks substantially empty,
having a first weight, displacing a first amount of displaced
water, having the stern-down trim angle .theta..sub.1, the first
amount 52 of hull bottom 22 in the water, the first amount of water
forced through the funnel 28 defined by the inverted V-shape of the
bottom 12, and the relatively minor amount of water resistance, at
least one first wake W.sub.1 is generated , with a first wake
height W.sub.h1, of approximately 10-15 cm.
[0081] When the hull 12 moves through the body of water in the
dynamic surfing mode, with the ballast tanks 100% filled or at
least partially filled, having at least the second weight greater
than the first weight, displacing at least the second amount of
displaced water greater than the first amount of displaced water,
having the third trim .theta..sub.3 intermediate the stern-down
cruising mode trim .theta..sub.1, and the bow-down ballasted static
mode trim .theta..sub.3, the larger portion 54 of the W-shaped hull
bottom 22 in contact with the body of water, the increased second
amount of water forced through the funnel 28 defined by the central
inverted V-shape of the bottom 12, and the increased amount of
water resistance, at least one wake wave W.sub.2 is generated,
having a wave height W.sub.h2. W.sub.h2 of wake wave W.sub.2
generated in the dynamic surfing mode is greater than the wake
height W.sub.h1 of the wake W.sub.1 generated in the cruising
mode.
[0082] Preferably, the height W.sub.h2 of at least one wake wave
W.sub.2 is approximately 0.5 meters to approximately 2.7 meters,
depending on the length of hull 12. FIG. 19 graphically depicts
projected wave heights for hull lengths from 20 feet to 60 feet,
respectively.
[0083] In addition, the trim and displacement-altering ballast
system of the present invention allows the operator to fill or
partially fill selected ones of the respective ballast tanks, to
achieve various different moment arms, displacements, and trims, as
desired, to change wake wave heights. When selected ones or all of
the ballast tanks are filled or partially filled with ballast
water, and the boat operates in the dynamic surfing mode, with the
hull still squatting lower in the water, though not as low as with
the ballast tanks 100% filled, the hull is trimmed with a plurality
of trim angles .theta..sub.4 . . . .theta..sub.n. FIG. 18, for
example, depicts hull 12 in the dynamic surfing mode, with the
ballast tanks 50% filled.
[0084] The hull depicted in FIGS. 2-3 and 15-18 is a 43 foot yacht
hull. As stated above, however, the present invention is not
limited to this hull length. FIGS. 20A-20C depict a 20 foot hull.
FIGS. 21A-21C depict a 28 foot sport boat hull. FIGS. 22A-22C
depict a 35 foot cruiser hull. FIGS. 23A-23C depict a 60 foot
hull.
[0085] FIG. 24 broadly depicts changes in several static dimensions
of a 43 foot hull at different drafts from 0.46 meters to 0.74
meters, measured at 0.02 meter intervals.
[0086] FIG. 25 graphically depicts wake wave heights generated by
the hull in the dynamic surfing mode, versus distance from the
boat's transom at the boat's centerline CL, and also at one meter
and two meters away from the boat's CL (all wake wave heights being
measured from the bottom of the boat, with the baseline
representing a surface of the body of water). FIG. 25 depicts wave
height W.sub.h2 of at least one wake wave W.sub.2 of a plurality of
dynamic surfing mode wake waves W.sub.2. The wave height W.sub.h2
of wake wave W.sub.2 depicted in FIG. 25 is approximately 1.5-2.0
meters.
[0087] FIG. 26 graphically depicts a plurality of wake waves
generated in the wake of the hull during the dynamic surfing
mode.
[0088] FIG. 27 depicts a height of one wake wave generated by the
hull during the dynamic surfing mode versus distance from the
boat's centerline and distance from the boat's transom.
[0089] FIGS. 25-27, viewed together, demonstrate that at least one
wake wave W.sub.2 generated by the hull in the dynamic surfing mode
is relatively large and extends for a relatively long time and
distance in the wake of the hull 12, thereby enabling the
wakesurfer to have a much longer ride, limited only by the surfer's
leg strength, skill, and physical conditioning.
[0090] Further in accordance with the invention, the wakesurfing
boat 10 is self-propelled. One or more engines (not shown) are
linked via appropriate shafts, gears, and linkages (also not
shown), to a pair of counter-rotating propellers 45 and 46,
projecting from a transom 48 at the stern 16 of hull 12. FIG. 28
depicts inward-rotating propellers 45 and 46. As broadly depicted
in FIG. 22, propeller 45 rotates in a clockwise direction .phi.hd
1, and propeller 46 rotates in a counter-clockwise direction
.phi..sub.2.
[0091] It will be apparent to those skilled in the art that various
modifications, and variations can be made to the preferred
embodiment described above, without departing from the spirit or
scope of the invention. The present invention covers any such
modifications thereof, provided they fall within the scope of the
claims and their equivalents.
* * * * *