Note: Descriptions are shown in the official language in which they were submitted.
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BUOYANT, VARIABLY BUOYANT AND NON-BUOYANT FOIL STRUCTURES FOR
MARINE VESSELS AND WATERCRAFT
FIELD OF THE INVENTION
The present invention relates to buoyant, variably buoyant and non-buoyant
foil structures for
marine vessels and watercraft, and more particularly, relates to buoyant,
variably buoyant and
non-buoyant foil structures for marine vessels and watercraft that provide
increased operational
stability.
to
BACKGROUND OF THE lNVENTION
Conventional watercraft (which term "watercraft" will be understood
hereinafter to include all
manner of marine vessels, including ships, boats, seaplanes, and personal
watercraft adapted for
use in either commercial, pleasure, military, shipping or other context,
whether powered by
engine, wind or otherwise), may experience undesirable pitching and rolling
during normal
operation under wavy or unsettled marine conditions. For example, the buoyancy
of the
watercraft in motion may cause the watercraft to pitch in an undesirable and
perhaps dangerous
manner when encountering a sufficiently large wave. For example, upon
transversing a large
wave, the buoyant hull of the watercraft may briefly raise the bow of the
watercraft, and
thereafter the stern of the watercraft, as the watercraft passes partially
over and partially through
the large wave. When the wave is insubstantial, or the where the watercraft is
of very substantial
mass relative to the size of the wave, the wave may have little effect on the
pitch or roll of the
watercraft. In other circumstances, however, a substantial wave may
significantly and negatively
effect the operation of the watercraft, and may place the watercraft, its
cargo and crew at
significant risk of harm or loss.
It is desirable to provide a watercraft with increased stability, and with
reduced pitching action
when encountering waves, particularly waves that would otherwise significantly
and negatively
affect the operation of the watercraft.
It is also desirable to provide a watercraft with increased stability and with
reduced rolling action
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when encountering waves, particularly waves that would otherwise significantly
and negatively
affect the operation of the watercraft.
SUMMARY OF THE INVENTION
Accordingly, one object of the present invention is to provide a watercraft
with increased
stability, and with reduced pitching action when encountering waves,
particularly waves that
would otherwise significantly and negatively affect the operation of the
watercraft.
Another object of the present invention is to provide a watercraft with
increased stability and
with reduced rolling action when encountering waves, particularly waves that
would otherwise
significantly and negatively affect the operation of the watercraft.
According to one aspect of the present invention, there is provided a
watercraft. A side-hull
extends downwardly from each side of a hull of the watercraft. A foil extends
downwardly and
inwardly from each side-hull.
According to another aspect of the present invention, there is provided a
method for operating a
watercraft. The watercraft comprises a hull having a side-hull extending
downwardly from each
side of the hull. A foil extends downwardly and inwardly from each side-hull.
The watercraft is
propelled to a speed sufficient for planing such that a substantial portion of
lift acting on the
watercraft is provided through contact between a portion of a bottom surface
of each foil and the
water.
An advantage of the present invention is that it provides a watercraft with
increased stability, and
with reduced pitching action when encountering waves, particularly waves that
would otherwise
significantly and negatively affect the operation of the watercraft.
A further advantage of the present invention is that it provides a watercraft
with increased
stability and with reduced rolling action when encountering waves,
particularly waves that would
otherwise significantly and negatively affect the operation of the watercraft.
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BRIEF DESCRIPTION OF THE DRAWINGS
A preferred embodiment of the present invention is described below with
reference to the
accompanying drawings, in which:
Figures 1A, 1B and 1C are a side view, a front view and a bottom view,
respectively, of
one embodiment of the present invention positioned 'at rest' in the water;
Figures 2A, 2B and 2C are a side view, a front view and a bottom view,
respectively, of
the embodiment of the present invention illustrated in Figures 1A, 1B and 1C
positioned
"on plane", in the water;
Figures 3A, 3B, 3C, 3D, 3E, 3F, 3G and 311 are side and front views of the
present
invention illustrated in Figure 1A, on plane, passing through a wave;
Figure 31 is a view of the leading edge of the foil of the present invention
having pierced
through the leading edge of a wave;
Figures 4A, 4B and 4C are a side view, a front view and a bottom view,
respectively, of
an embodiment of the present invention having non-buoyant foils and side-
hulls,
positioned 'at rest' in the water;
Figures 4D, 4E and 4F are a side view, a front view and a bottom view,
respectively, of
the embodiment of the present invention illustrated in Figures 4A, 4B and 4C
positioned
"on plane", in the water;
Figures 5A, 5B and 5C are a side view, a front view and a bottom view,
respectively, of
an embodiment of the present invention having a substantially flat wet deck,
positioned
'at rest' in the water;
Figures 5D, 5E and 5F are a side view, a front view and a bottom view,
respectively, of
the embodiment of the present invention illustrated in Figures 5A, 5B and 5C
positioned
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"on plane", in the water;
Figures 6A, 6B and 6C are a side view, a front view and a bottom view,
respectively, of
an embodiment of the present invention having a deep-v type centre hull
positioned
between vertically shortened side-hulls, positioned 'at rest' in the water;
Figures 6D, 6E and 6F are a side view, a front view and a bottom view,
respectively, of
the embodiment of the present invention illustrated in Figures 6A, 6B and 6C
positioned
"on plane", in the water;
Figures 7A, 7B and 7C are a side view, a front view and a bottom view,
respectively, of
an embodiment of the present invention having a deep-v type centre hull
positioned
between vertically shortened side-hulls with the side-hulls and foils having
truncated
length, positioned 'at rest' in the water; and,
Figures 7D, 7E and 7F are a side view, a front view and a bottom view,
respectively, of
the embodiment of the present invention illustrated in Figures 7A, 7B and 7C
positioned
"on plane", in the water.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Unless defined otherwise, all technical and scientific terms used herein have
the same meaning
as commonly understood by one of ordinary skill in the art to which the
invention belongs.
Although any methods and materials similar or equivalent to those described
herein can be used
in the practice or testing of the present invention, the preferred methods and
materials are now
described.
In an embodiment of the present invention, as illustrated in Figures 1A, 1B
and 1C, a watercraft
generally shown as 10 is provided, having overall dimensions of 40 ft. long by
10.5 ft. wide by
7.5 ft high (from the surface of the boat deck to the bottom edge of fins
160). In the embodiment
of the invention depicted in Figures 1A, 1B and 1C, the watercraft 10 has the
hull 20, cabin 25,
side-hulls 30 on both sides thereof, and extending downwardly in a
substantially vertical
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orientation, and from each of which side-hulls 30 depend downwardly and
inwardly foils 40. In
this embodiment of the invention, the side-hulls and foils are watertight,
substantially hollow,
and by means of spaced strengthening rib members positioned within the side-
hulls 30 and foils
40, are rigidly and securely engaged with the watercraft 10 and form part of
the hull 20 of the
watercraft 10, it being understood that alternative techniques known to a
person skilled in the art
may alternatively be utilized to rigidly and securely engage the side-hulls
and foils to form part
of the watercraft 10, including, for example, with the components being made
of a composite
material such as fiberglass, manufactured and assembled using conventional
molding and
bonding techniques.
In this embodiment of the watercraft 10, each of the foils 40 have an upper
surface 50, and a
lower surface 60, that extend substantially along the upper and lower sides of
each of the foils
40, respectively. Each foil 40 has a leading edge 65 and an upper leading
surface 70, and lower
leading surface 80, extending rearwardly from leading edge 65 that smoothly
transition into the
upper surface 50 and a lower surface 60 respectively.
Optionally, an extension of the upper leading surface 70 and the lower leading
surface 80 from
the leading edge 65 increases with decreasing distance to the side-hulls 30.
The watercraft of the present invention optionally has a wet deck 90 of
varying sizes, shapes and
volumes ranging from a flat surface with the least volume to a deep-v with the
greatest volume,
including shapes such as lateral 'steps', known as a `stepped-hull' and other
monohull
designs/shapes known to someone skilled in the art, positioned on a lower
surface of the hull as
more fully described herein.
In this embodiment of the invention, the watercraft 10, when stationary or
while operating at
below planing speed, is as illustrated in Figures 1A, 1B and 1C positioned in
the water such that
the wet deck 90 is above the surface of the water 100, the buoyant side-hulls
30 and foils 40
maintaining the wet deck 90 and upper hull above the surface of the water 100.
In one embodiment of the present invention, short vertical fins 160 extend
downwardly from the
lower edges of the foils 40 to provide additional directional stability
particularly when the
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watercraft is operating at planing speeds.
Optionally, the length of the side-hulls 30 and the foils 40 is truncated to
some extent depending,
for example, on the operational conditions the watercraft 10 is designed for.
IN OPERATION IN WAVE-LESS OR SMALL WAVE CONDITIONS
As the watercraft 10 velocity is increased, the watercraft 10 begins to plane
as illustrated in
Figures 2A, 2B and 2C, that is, the watercraft is angled 63 upwardly, and is
partially elevated
(relative to comparable operation of the watercraft at sub-planing velocity),
the contact between
the watercraft 10 and the water being substantially limited to the planing
surface 62 of a length
of the lower surface of each foil proximate the stern of the watercraft, as
illustrated in Figure 2C.
Lines 170, 172, 174 and 176 indicate contact lines with the water surface
during operation of the
watercraft 10 while planning with: line 170 indicating the contact line of the
lower surface 60 of
the foil 40 when 'on plane'; line 172 indicating the contact line of the fin
160 and the upper
surface 70 of the foil 40 when 'on plane'; line 174 indicating the contact
line of the fore portion
of the foils 40 when 'on plane'; and line 176 indicating the contact line of
the aft portion of the
foils 40 when 'on plane'.
IN OPERATION IN SUBSTANTIAL WAVES
As illustrated in Figure 3A, 3B, 3C, 3D, 3E, 3F, 30, 3H and 31, as the planing
watercraft 10
approaches a substantial wave 120, the leading edge of the foil 65 pierces the
leading edge 122
of wave 120 as illustrated in Figure 3C, 3D and 31 and cuts through an upper
portion 124 of
wave 120 as illustrated in Figure 30, the upper portion 124 of the wave 120
being directed above
the foil by the leading edge of the foil 65 and the upper leading surface 70
thereof so that the
water forming the upper portion of the wave passes through the tunnel 140 (the
tunnel 140 being
that passage formed by the wet deck 90, side-hulls 30 and foils 40 as
illustrated in Figures 3B,
3D, 3F). In this way, the water from the upper portion 124 of the wave 120
passes through the
tunnel 140, exiting therefrom at the stern of the watercraft 10 with reduced
overall pitching effect
on the watercraft 10, as illustrated in Figures 3G and 3H. The volume of water
from the top of
the wave passes over the upper surface 50 of the foil 40 and is counteracting
the lift from the foil
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40, and as this volume of water continues down the tunnel the buoyancy of the
foils 40 and the
side-hulls 30 being immersed deeper in the water lifts the watercraft 10 up
but with substantially
reduced pitching. Furthermore, the volume of water flowing over the upper
surface 50 of the
foils 40 aft counteract the buoyant force of the watercraft 10 acting at the
stern and substantially
prevent the same from rising up as the watercraft 10 exits the wave, thus the
watercraft 10
maintains a substantially level orientation. Preventing the stern from
pitching up and
consequently the bow from pitching down when passing through a wave enables
the watercraft
to penetrate the following wave at a substantially correct angle and to repeat
the process at
substantially level orientation. Simultaneously, as this buoyant/lifting
action is occurring, there is
10 a hydraulic action of a portion of the volume of water on the upper
surface 50 of the foils 40
evacuating down through the gap 165 between the foils 40, dampening the
vertical movement
and 'distributing' it along the length of the gap 165 and tunnel 140. A
truncated lower portion of
the wave may be directed beneath the foil by the leading edge of the foil 65
and the lower
leading surface 80 thereof so that the water forming the truncated lower
portion 126 of the wave
120 passes along the lower surface of the foil, this truncated lower portion
126 of the wave 120
is of reduced height relative to the full wave itself and therefor has reduced
lifting impact on the
lower surface of the foils and reduced lifting impact, reduced upward
acceleration and reduced
lift of the watercraft 10, and reduced likelihood of negative impact of the
watercraft's crew,
personnel, cargo and equipment.
In situations when waves are encountered that are large enough to cause the
bow of the
watercraft 10 to pitch up, the gap 165 between the foils 40 provides a
dampening effect and
reduces the likelihood of the watercraft 10 getting airborne. If the
watercraft gets airborne the
gap 165 between the foils 40 acts again as a dampener reducing the overall
effect of the slam
when the watercraft enters the water again.
Increased pitch stability is also experienced at non-planing speed or when
transitioning the
watercraft from non-planing to planing. Here, the weight of the water passed
through the tunnel
140 and acting on the upper surfaces 50 of the foils 40 reduces the lifting
impact of the wave
resulting in a reduced upward acceleration and reduced lift of the watercraft
10. The gap 165
between the foils 40 allows water to flow between the space above the foils 40
to the space
below the foils 40 resulting in a hydraulic dampening effect along the length
of the gap 165.
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The weight of the water passed through the tunnel 140 and acting on the upper
surfaces 50 of the
foils 40 also dampens roll movement of the watercraft 10 at non-planing speed
or when
transitioning the watercraft from non-planing to planing. For example, if the
watercraft 10 is
tilting towards starboard due to side impact of a wave, the weight of the
water acting on the
upper surface 50 of the foil 40 on the port side of the watercraft 10 is
reducing the tilting effect
of the wave impact.
Roll movement of the watercraft 10 is also dampened when planing. For example,
if the
watercraft 10 is tilting towards starboard due to side impact of a wave, the
size of the planing
surface 62 on the starboard foil is greater than the size of the planing
surface 62 on the port foil,
increasing lift on the starboard side counteracting the roll movement.
When inducing a turn, the watercraft 10 tends to sideslip, i.e. the line of
thrust and the center of
gravity are offset. Due to the resulting change in water flow the outboard
foil 40 tends to raise up
caused by increased lift acting on the lower surface 60 of the outboard foil
40. Simultaneously,
due to this change in water flow the inboard foil 40 tends to lower into the
water due to the side
slipping action of the watercraft 10. Consequently, there is more water
flowing over the upper
surface 50 of the inboard foil 40 driving it deeper into the water until it
reaches equilibrium due
to increased buoyancy of the inboard foil 40. When the thrust vector is
returned to be in line with
the watercraft 10, the same returns to its original level equilibrium.
The gap 165 between the foils 40 allows water to flow from the space above the
foils 40 to the
space below the foils 40, generally providing a dampening effect on pitch and
roll movement of
the watercraft 10.
NON-BUOYANT EMBODIMENT
In one embodiment of the invention, as illustrated in Figures 4A, 4B, 4C, 4D,
4E and 4F, the
foils 40 and/or side-hulls 30 are either substantially neutrally buoyant, or
alternatively, non-
buoyant, the overall watercraft 10 afloat at rest, as illustrated in Figures
4A, 4B and 4C, in
consequence of the buoyant effect of the overall configuration of the hull of
the watercraft 10,
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including, for example, the wet deck. By way of example only, substantially
neutrally buoyant,
or alternatively, non-buoyant foils 40 and/or side-hulls 30 may be used on
either planing or non-
planing watercraft.
In the case of planing watercraft 10, substantially neutrally buoyant, or
alternatively, non-
buoyant foils 40 and/or side-hulls 30 may be used, for example, where buoyancy
of the foils 40
and/or side-hulls 30 is undesirable or unnecessary, or where the selected
buoyant materials or
internal construction of the foils 40 and/or side-hulls 30 may otherwise
result in a structurally
less robust water craft. By way of example, substantially neutrally buoyant,
or alternatively, non-
buoyant foils 40 and/or side-hulls 30 may be used on buoyant personal
watercraft, pontoon boats,
pleasure boats, off-shore fishing boats and other rugged or hard-use
watercraft that may, for
example, from time to time, come into contact with the sea or lake bottom, or
shore may benefit
from non-buoyant foils 40 and/or side-hulls 30, and in one embodiment of the
present invention,
truncated foils and side-hulls may alternatively be used.
In the case of non-planing watercraft 10, substantially neutrally buoyant, or
alternatively, non-
buoyant foils 40 and/or side-hulls 30 may be used, for example, where the
buoyancy of the foils
40 and/or side-hulls 30 is relatively insignificant when compared to the
overall mass of the
watercraft, such as in the case of a large cargo ship.
OPERATION OF NON-BUOYANT EMBODIMENT
In this embodiment of the invention, the watercraft, when stationary or while
operating at below
planing speed is as illustrated in Figures 4A, 4B and 4C positioned in the
water such that the wet
deck is in contact with or fully or partially submerged in the water. As the
velocity of the
watercraft 10 is increased, the watercraft 10 begins to plane, that is, the
watercraft angles 63
upwardly, and is partially elevated, the contact between the vessel and the
water being
substantially limited to the planing surface 62 of a length of the lower
surface of each foil
proximate the stern of the watercraft, as illustrated in Figures 4D, 4E and
4F.
VARIABLY BUOYANT EMBODIMENT
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In one embodiment of the invention, the foils 40 and/or side-hulls 30, (or
tanks or cavities within
the foils 40 and/or side-hulls 30), may be variably filled, or variably
partially filled with ballast
water, thereby variably fully or partially reducing the overall buoyant effect
of the foils and/or
side-hulls on the watercraft as a whole, or alternatively may be variably
emptied, or variably
partially emptied of ballast water, thereby variably increasing the buoyant
effect of the foils
and/or side-hulls on the watercraft as a whole. The foils 40 and/or side-hulls
30, (or tanks or
cavities within the foils 40 and/or side-hulls 30) may be filled or emptied by
one or more pumps
that may be used in a conventional and controlled manner by the watercraft
operator in such
manner as to precisely control the volume of water within the foils 40 and/or
side-hulls 30, (or
tanks or cavities within the foils 40 and/or side-hulls 30).
Alternatively the foils, side-hulls, tanks or cavities may be filled/drained
passively, by providing
carefully positioned openings in the surfaces of the foils or side-hulls such
that the openings are
positioned below the water surface when the vessel comes to rest for filling
and above the water
surface when the vessel transitions to a planning mode for draining. Further
alternatively, the
openings are provided with a valve mechanism enabling the operator to control
filling/draining
of the tanks. For example, the operator chooses to keep some water contained
within the foils
and/or side-hulls during planning.
OPERATION OF VARIABLY BUOYANT EMBODIMENT
While the watercraft 10 is at rest, increased pitch stability may be
desirable. In this circumstance,
the watercraft 10 may be lowered relative to the surface of the water so that
the wet deck is in
contact with and/or partially submerged in the water, as illustrated in
Figures 4A, 4B and 4C,
thereby providing buoyant support for the watercraft 10 along that length of
the wet deck that is
in contact with and/or partially submerged in the water, thereby increasing
the pitch and roll
stability of the watercraft 10. For example, the increased stability of the
watercraft 10 at rest
allows for loads to be distributed over the watercraft 10 with the same
reacting less sensitively to
the changes of the load distribution. When the increased pitch stability is no
longer beneficial, or
where reduced overall watercraft mass (including ballast water) is desirable
(for example, when
planing, or when transitioning the watercraft from non-planing to planing),
the ballast water may
be variably and fully emptied from the foils 40 and/or side-hulls 30 (or tanks
or cavities within
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the foils 40 and/or side-hulls 30). As the watercraft 10 velocity is
increased, the watercraft 10
begins to plane, that is, the watercraft angles 63 upwardly, and is partially
elevated, the contact
between the vessel and the water being substantially limited to the planing
surface 62 of a length
of the lower surface of each foil proximate the stern of the watercraft, as
illustrated in Figures
4D, 4E and 4F.
PONTOON-TYPE EMBODIMENT
In one embodiment of the invention, as illustrated in Figures 5A, 5B, 5C, 5D,
5E, and 5F, the
watercraft 10 comprises hull 20 having a substantially flat wet deck 90,
providing a pontoon-type
watercraft 10 operated, for example, from helm 180 disposed on the hull 20.
Side-hulls 30 extend
on both sides of the hull 20 downwardly in a substantially vertical
orientation, and from each of
which side-hulls 30 depend downwardly and inwardly foils 40. Operation of the
pontoon-type
watercraft 10 is similar to the operation of the watercraft illustrated in
Figures 1A, 1B, 1C, 2A,
2B and 2C hereinabove with Figures 5A, 5B and 5C depicting the watercraft 10
at rest or non-
planing mode and Figures 5D, 5E and 5F depicting the watercraft 10 in planing
mode. It is
understood, that the side-hulls 30 may be provided having various shapes such
as, for example,
cylindrical shapes, box beam shapes, or monohull shapes. Furthermore, the side-
hulls 30 may be
buoyant or variably- buoyant, while the foils 40 may be buoyant, variably-
buoyant, or non-
buoyant.
SHORTENED SIDE-HULL EMBODIMENT
In one embodiment of the invention, as illustrated in Figures 6A, 6B, 6C, 6D,
6E and 6F, the
side-hulls 30 are shortened in relation to the center hull 20 compared to the
embodiments
described hereinabove. Here, the foils 40 project downward to approximately a
same horizontal
plane as the bottom of the center hull 20. The side-hulls 30 and the foils 40
may be buoyant, non-
buoyant, or variable buoyant.
OPERATION OF SHORTENED SIDE-HULL EMBODIMENT
In this embodiment of the invention, the watercraft 10, when stationary or
while operating at
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below planing speed is as illustrated in Figures 6A, 6B and 6C positioned in
the water such that
the wet deck is in contact with or fully or partially submerged in the water.
As the velocity of the
watercraft 10 is increased, the watercraft 10 begins to plane, that is, the
watercraft angles 63
upwardly, and is partially elevated, the contact between the vessel and the
water being
substantially limited to the planing surface 62 of a length of the lower
surface of each foil
proximate the stern of the watercraft, as illustrated in Figures 6D, 6E and
6F. It is understood,
that the deep-v centre hull, as illustrated in Figures 6A, 6B, 6C, 6D, 6E and
6F, reduces the
volume of the tunnel 140 compared to the embodiment illustrated in Figures 1A,
1B, 1C, 2A, 2B,
and 2C.
ft)
TRUNCATED FOILS AND SHORTENED SIDE-HULL EMBODIMENT
As illustrated in Figures 7A, 7B, 7C, 7D, 7E and 7F, foils and shortened side-
hulls 30 of
truncated length are positioned proximate the stern of watercraft 10.
The present invention has been described herein with regard to preferred
embodiments.
However, it will be obvious to persons skilled in the art that a number of
variations and
modifications can be made without departing from the scope of the invention as
described
herein.
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