U.S. patent application number 12/543783 was filed with the patent office on 2011-02-24 for marine propulsion system and method.
Invention is credited to Donald L. Ekhoff.
Application Number | 20110045718 12/543783 |
Document ID | / |
Family ID | 43605728 |
Filed Date | 2011-02-24 |
United States Patent
Application |
20110045718 |
Kind Code |
A1 |
Ekhoff; Donald L. |
February 24, 2011 |
MARINE PROPULSION SYSTEM AND METHOD
Abstract
A marine propulsion system comprises a propulsion wheel that is
rotary driven and that includes an arrangement of water-channeling
members located to extend only partially below the water level. As
a member is partially submerged, water is collected, compressed,
accelerated, and ejected as a water jet. An ejection end of each
member may be specifically designed to achieve desired thrust
characteristics. The water-channeling members may be non-complex,
such as being cup-shaped or spoon-shaped, but may include complex
curvatures in order to achieve desired thrust characteristics. A
hull may be used to precondition the water level presented to the
water-channeling members.
Inventors: |
Ekhoff; Donald L.; (Post
Falls, ID) |
Correspondence
Address: |
SCHNECK & SCHNECK
P.O. BOX 2-E
SAN JOSE
CA
95109-0005
US
|
Family ID: |
43605728 |
Appl. No.: |
12/543783 |
Filed: |
August 19, 2009 |
Current U.S.
Class: |
440/90 |
Current CPC
Class: |
B63H 5/02 20130101; B63H
1/04 20130101 |
Class at
Publication: |
440/90 |
International
Class: |
B63H 1/04 20060101
B63H001/04 |
Claims
1. A propulsion system for a marine vessel comprising: a rotary
drive assembly for applying drive power; a propulsion wheel coupled
to said rotary drive assembly such that operation of said rotary
drive assembly causes rotation of said propulsion wheel; a
plurality of water-channeling members connected to said propulsion
wheel to extend outwardly from said propulsion wheel, each said
water-channeling member having a cavity configured such that
incoming water is concentrated and accelerated, each said
water-channeling member further having an ejection end having a
geometry for ejection of said water from said cavity of said
water-channeling member; and a mount configured to secure said
propulsion wheel to said marine vessel such that during said
rotation of said propulsion wheel each said water-channeling member
is positioned to periodically extend only partially into water in
which said marine vessel resides and such that a quantity of said
water is received within each said water-channeling member upon
partial extension into said water.
2. The propulsion system of claim 1 wherein said cavity of each
said water-channeling member is defined by inwardly sloping
surfaces, such that said incoming water is concentrated and
accelerated toward a centerline of said cavity, said ejection end
being located and oriented to continue laminar flow of said water
for said ejection.
3. The propulsion system of claim 1 wherein each said
water-channeling member has one of a cup-shape or a
spoon-shape.
4. The propulsion system of claim 1 further comprising a hull, said
mount positioning said propulsion wheel such that said
water-channeling members only partially below a bottom of said hull
during said rotation of said propulsion wheel, said hull being
configured to define a selected water level with respect to
operation of said propulsion wheel.
5. The propulsion system of claim 4 wherein said propulsion wheel
has a rotational axis positioned relative to said bottom of said
hull such that said ejection ends of said water-channeling members
remain above said bottom of said hull during said rotation of said
propulsion wheel.
6. The propulsion system of claim 4 wherein said hull is attached
to said marine vessel by a suspension that enables movement of said
hull relative to said marine vessel in response to waves and other
changes in levels of water in which said marine vessel resides.
7. The propulsion system of claim 1 wherein said ejection end of
each said water-channeling member has a configuration to define a
direction of an ejected water jet as said propulsion wheel is
rotated.
8. The propulsion system of claim 7 wherein said configuration of
said ejection end includes a termination that is angled
downwardly.
9. The propulsion system of claim 1 wherein said propulsion wheel
has a rotational axis, said rotary drive assembly being connected
to drive said propulsion wheel about said rotational axis, said
water-channeling members being arranged in at least two axially
separate rows, each said row having a plurality of aligned said
water-channeling members.
10. The propulsion system of claim 9 wherein said water-channeling
members of adjacent said rows are axially misaligned, such that
said water-channeling members are staggered.
11. The propulsion system of claim 1 wherein each said
water-channeling member has a plurality of fingers position to
scoop said water during said rotation of said propulsion wheel.
12. A propulsion method for a marine vessel comprising: providing a
propulsion wheel having a plurality of water-channeling members
connected to said propulsion wheel to extend outwardly therefrom,
each said water-channeling member having a cavity to receive,
concentrate and direct water; connecting said propulsion wheel to a
marine vessel such that said water-channeling members are
positioned to periodically extend only partially into water when
said propulsion wheel is rotated, including orienting said
water-channeling members such that said cavities acquire a quantity
of said water when partially extended into said water; and driving
said propulsion wheel so as to rotate in a manner to power said
marine vessel, said connecting of said propulsion wheel including
directing each said water-channeling member such that said water is
collected and concentrated in conformance with a contour of said
cavity and is ejected from said water-channeling member following
acceleration of said water.
13. The propulsion method of claim 12 further comprising
controlling a level of water presented to said water-channeling
members, such that said level remains substantially constant
regardless of changes in conditions of water in which said marine
vessel resides.
14. The propulsion method of claim 13 wherein controlling said
level of water includes connecting said propulsion wheel within a
hull such that said water-channeling members are able to extend
only partially below a bottom of said hull.
15. The propulsion system of claim 14 further comprising attaching
said hull to said marine vessel using a suspension system,
including enabling said hull to respond to waves independently of
said marine vessel.
16. The propulsion method of claim 12 wherein connecting said
water-channeling members includes establishing an angle of said
water-channeling members to provide a lifting force to said marine
vessel during driving of said propulsion wheel, said lifting force
being variable with changes in rotational speed of said propulsion
member.
17. The propulsion method of claim 12 wherein connecting said
water-channeling members includes providing at least two rows that
are offset axially.
18. The propulsion method of claim 17 wherein connecting said
water-channeling members further includes providing staggering for
adjacent said rows, such that said water-channeling members in said
adjacent rows are axially misaligned.
19. The propulsion method of claim 12 wherein providing said
propulsion wheel includes defining said water-channeling members to
have one of a spoon-shape or a cup-shape.
Description
TECHNICAL FIELD
[0001] The invention relates generally to powering a marine vessel
and more particularly to a rotary drive system for marine
propulsion.
BACKGROUND ART
[0002] There is a wide variety of known techniques for propelling a
marine vessel. Manual techniques include the use of oars, paddles,
and poles. Sails also provide propulsion without the need of
motors. However, motorized propulsion typically provides greater
control and greater speed.
[0003] Motorized marine propulsion techniques include the use of
paddle wheels, screw propellers, and water jets. Paddle wheels are
uncommon, since conventional paddle wheels are bulky and tend to be
inefficient. The paddle wheels are basically "pushers" in which
flat paddle planks are rotated through water, thereby using the
viscous flow resistance of the paddle to propel the marine vessel
along the surface of the water. The inefficiency results from the
insertion and extraction losses, as well as turbulence losses. In
comparison, the screw propeller exhibits turbulence losses, but is
somewhat more efficient because the propeller remains submerged.
Water jets direct a high speed stream of water from a nozzle. While
water jets provide advantages over other techniques, inefficiency
results from the high levels of wetted surface and turbulence
involved in moving an incompressible fluid through an often complex
configuration at high velocity.
[0004] While the known techniques operate well for their intended
purposes, further advantages are sought. Such advances may be in
one or more of a number of areas, such as efficiency, speed,
safety, and adaptability.
SUMMARY OF THE INVENTION
[0005] A marine propulsion system in accordance with the invention
is comprised of a rotary driven propulsion wheel having an
arrangement of water-channeling members with cavities that are
configured to first concentrate incoming water and then eject the
water as an accelerated flow. The mounting and the driving of the
propulsion wheel are such that each water-channeling member
periodically extends only partially into the water in which the
marine vessel resides. As a particular water-channeling member is
partially extended into water, a quantity of water is "scooped"
within the cavity of the member. Inclined surfaces of the cavity
cause the scooped water to be channeled from the submerged portion
upwards toward a central region of the cavity. The water continues
to follow the contour of the cavity surfaces and is ejected in a
rearward direction as an accelerated jet of water.
[0006] In one embodiment, the cavity surface of each
water-channeling member terminates in a curved end. The design of
the curved end determines the direction of the water jet ejected
from the member. While geometries of the system components will
vary with the needs for a particular application of the invention,
it is likely that the ejected water from a curved end will be a
water jet with a velocity much greater than the velocity of the
water-channeling member. Thus, the curved end is preferably
directed such that the jet avoids contact with the other
water-channeling members of the propulsion wheel, thereby avoiding
efficiency losses.
[0007] The water-channeling members may be connected to the
propulsion wheel along its exterior surface or may be integrated to
the propulsion wheel during manufacture. Rather than having a
planar region to contact the water, each water-channeling member
may be described as having a cup-shape or a spoon-shape, although
more complex shapes have advantages. Regardless of the particular
shape of each member, water is gathered under the influences of
inertial forces, consolidated into a high speed jet, and then
ejected rearward. The jet ejection event is a direct function of
the rotational location of the water ingestion. Once the water is
ingested, the water follows the contour of the cavity while it
consolidates/accelerates into a jet. The direction of this jet from
the curved end is a function of the placement of the water intake
plus a few degrees of rotation, which is due to the time required
for the ingested water to travel through the water-channeling
member. At rest, water will rise into the "hole" being formed by
the "digging" of consecutive scoops, but as speed increases, water
is additionally made available towards the forward edge of the
rotating propulsion wheel, due to the advancement of the marine
vessel through the body of water.
[0008] The curved end of each water-channeling member can be
configured to define thrust characteristics. For example, the
mounting of the water-channeling members and the geometry of the
curved ends may be designed to define a direction of propulsion
that is nominally parallel to the water level surrounding the
marine vessel. Alternatively, the curved end may have a termination
at a downward angle toward the water level, such that a component
of lifting force is applied in addition to the lateral, forward
propulsion. This lifting force may be used to reduce friction as
the marine vessel is moved along the surface of the water. In
addition, the water-channeling members may be designed to create a
high pressure area that has a tendency to lift the vessel by
inciting hydraulic pressures acting directly on the
water-channeling members. Other embodiments may have more of a lip
which will cup water into the cavity to increase thrust while
decreasing lift.
[0009] If the water-channeling members are too closely spaced along
the propulsion wheel, water projected from one member may strike
the reverse side of the subsequent member, regardless of the design
of the curved end. If a greater amount of thrust is desired, the
water-channeling members may be arranged in multiple axially
separated rows, with each row having a number of aligned members.
Additionally, the members of adjacent rows may be axially
misaligned, such that the members of the adjacent rows are
staggered.
[0010] The mount which secures the propulsion wheel to the marine
vessel may be configured to provide additional advantages. The
mount may be enabled to move in a direction perpendicular to the
water surface, thereby allowing the propulsion wheel to adapt
dynamically. For example, articulating legs may be used in a manner
similar to suspension systems for land vessels. Then, the
propulsion wheel is free to rise or lower relative to the marine
vessel. This permits a smoother passage of the marine vessel than
would be achieved if the propulsion wheel were rigidly mounted to
the vessel. Using such a "suspension system" or other means of
absorbing path disruption in a controlled manner is most important
for Ultra high Speed designs that may use the invention.
[0011] Amphibious embodiments are contemplated. For example, the
water-channeling members may be adapted to allow travel along a
beach or along the surface of ice. Alternatively, the propulsion
wheel may be connected to rolling elements which are driven by the
same rotary drive and which support the vessel upon exiting from
the water. This rolling action will also accommodate passage over
submerged objects such as ice and will have minimal detrimental
effect on wildlife.
[0012] This technology is similar to the turbine concept used in
generating hydropower. While other differences exist, the most
significant difference between the invention and the
power-generating systems (for example, the Pelton wheel and the
Turgo wheel) is that the propulsion wheel of the invention is
powered through water, rather than being powered by water.
[0013] Drag can be further reduced by including a hull or similar
structure positioned forwardly of the propulsion wheel to
precondition the water level. For example, the mounting of the
propulsion wheel may include a hull, below which the end regions of
water-channeling members periodically extend to contact water. The
rotational axis of the propulsion wheel is at a distance from the
bottom of the hull to limit emersion of the water-channeling
members as described above. Using the hull, the water level
surrounding the marine vessel is consistently higher than the
"apparent" level of water contacted by the members. This is because
the hull "conditions" the surface of the water contacted by the
members.
[0014] An advantage of the invention is that a greater efficiency
is possible, as compared to conventional propeller-drive and
jet-drive systems for marine vessels, because cavitation losses and
large surface frictional pumping losses are significantly reduced
or even eliminated. Another advantage is that maintenance and
service requirements are reduced, since under normal circumstances
only a small portion of the moving components of the propulsion
system extend to the water and the large portion is easily
accessible.
[0015] The propulsion system functions as a gyro stabilizer for the
marine vessel. Where the propulsion wheel spins on a horizontal
axis at high speed and with a considerable diameter and mass, the
propulsion wheel will resist vessel rotations about its rotational
axis and a vertical axis. This is most desirable when the vessel is
at speed in rough water. It is further contemplated that this
effect may be applied when propulsion of the vessel is not desired.
The propulsion wheel can be raised sufficiently to spin freely
without contact with water. Sea sickness is a result of the
undulating "figure eight" motion that is unfamiliar to land
passengers. The invention may be used to reduce vessel motion to a
much simpler rocking of the vessel about a port/starboard axis,
thereby reducing common side-to-side rocking motion. It is possible
to place an additional gyro-wheel within the propulsion wheel, so
that this advantage is available irrespective of propulsion speed.
In military applications, this effect may be used to stabilize a
platform from which munitions are aimed.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a perspective view of one embodiment of a
propulsion system in accordance with the invention.
[0017] FIG. 2 is a perspective view of the system of FIG. 1 within
a hull.
[0018] FIG. 3 is a schematic view of the invention in an
operational mode.
[0019] FIG. 4 is an end view of the propulsion system of FIG. 1 as
used within a tunnel hull.
[0020] FIG. 5 is a perspective view of an alternative embodiment of
a water-channeling member.
[0021] FIG. 6 is another embodiment of a water-channeling member in
accordance with the invention.
DETAILED DESCRIPTION
[0022] With reference to FIG. 1, a propulsion system 10 in
accordance with one embodiment of the invention includes two rows
of water-channeling members 12 and 14 connected to a propulsion
wheel 30. The water-channeling members 12 are in a row that is
axially separate from the water-channeling members 14 of the other
row. The members 12 and 14 are "water-channeling," since they are
configured to collect water and channel the collected water so as
to provide a thrust having desired characteristics. In FIG. 1, the
members have a cup-shape, but other configurations are within the
scope of the invention, including spoon-shaped members and those
with a more complex geometry (for example, those which will be
described with reference to FIGS. 5 and 6).
[0023] The mounting of the water-channeling members 12 and 14 to
the propulsion wheel 30 may be accomplished using techniques known
in the art. In FIG. 1, each member is connected to a plate 18 which
is mounted to the propulsion wheel by fastening hardware, such as
screws or bolts. Alternatively, the water-channeling members may be
integrally formed with the propulsion wheel during a manufacturing
process. The structure of the illustrated propulsion wheel is
similar to that of a wheel of a land vessel.
[0024] In a typical embodiment, a motorized rotary drive is coupled
to operate the propulsion wheel 30. However, the propulsion system
may be manually driven, such as by coupling the propulsion wheel to
rotate as a person operates hand or foot pedals. Thus, the rotary
drive may include a motor engine or may be an assembly similar to
that of a bicycle.
[0025] In the embodiment of FIG. 1, the propulsion wheel 30 is
connected to a rotating central assembly 32 by three spokes 34. A
belt 33 or chain couples the central assembly 32 to a drive gear
35. A representation of a motor 50 is included for reasons of
explanation, but the rotary drive motor may vary significantly for
alternative packaging requirements. Mounting plates 44 may be used
to attach a pair of side walls 36 and 38 to a pivot plate 46 that
attaches to a stationary portion 42. A restriction pin 48 may be
included to set a limit as to the lower range of motion of the
pivot plate. While not shown, a second restriction pin may be used
to similarly limit the upper range of motion.
[0026] The side walls 36 and 38 are on opposite sides of the
propulsion wheel 30 to combine with a shroud 40 to cover the
water-channeling members 12 and 14, other than at a lower end of
the propulsion system. In the illustration of FIG. 1, the nearer
side wall 36 is shown in phantom, so as to allow the internal
components to be viewed.
[0027] In operation, only the lowermost portion of the propulsion
system 10 should reside below the system's "apparent water level."
Referring to FIGS. 1 and 2, this apparent water level is below the
level of the water in which the marine vessel resides. A hull 37
may be used to condition the water level so as to define the
apparent water level when the vessel is at speed. Only the bottom
39 of the hull is illustrated in FIG. 1, so that it may be seen
that the shroud 40 has a termination 52 that is generally along the
same horizontal plane with the hull bottom. This allows water to
enter the region that is between the two sidewalls 36 and 38 and
below the hull.
[0028] FIG. 3 represents the operation of the propulsion system 10,
but only one row of water-channeling members 12 is shown. Briefly
stated, each water-channeling member 12 is rotated into the surface
of the water, thereby collecting and accelerating the water in
conformance with the face of the member. Each water-channeling
member is contoured to include side features which constrain and
direct the water towards the centerline of the water-channeling
member, thereby placing compressive forces into the water stream.
These compressive forces act to accelerate the flow of said water
stream, causing the rearward ejected water stream to provide useful
forward thrust (Arrow 54 represents the forward direction). The
water-channeling member may be limited to an emersion of only
one-third of its length. That is, for purposes of propulsion, the
member is only one-third engaged. Water is gathered under the
influences of inertial forces, is consolidated into a high speed
jet 78, and is ejected rearward. The jet ejection event is a direct
function of the rotational location of the water ingestion. Once
the water is ingested, it follows the contour of the cavity in the
face of the member while it consolidates/accelerates into the jet.
The direction of this jet from the curved end of the member is a
function of the placement of the water intake plus a few degrees of
rotation, which is due to the time required for the ingested water
to travel through the water-channeling member. Each member 12 takes
a "bite" of the water as the member scoops into the water. The
successive bites (or scoops) are represented by different
crosshatchings of the "bites," which match the different hatchings
of the water-channeling members. At rest, water will rise into the
"hole" being formed by the "digging" of consecutive scoops, but as
speed increases, water is additionally made available towards the
forward edge of the rotating propulsion wheel, due to the
advancement of the marine vessel through the body of water.
[0029] As the propulsion system 10 drives the marine vessel
forward, the hull 39 functions to condition the water for smooth
successive "bites" by the rotating water-bearing members 12. The
efficiency of the system is increased if the propulsion wheel 30
and the members 12 are enclosed within the fairing (the side walls
36 and 38 and the shroud 40 that is shown in FIGS. 1 and 2). One
reason is that the members 12 should not be overfilled. A general
rule of thumb is that a member should take a "bite" which is
approximately one third of its total capacity to hold water.
"Overfilling" may result in performance that is typical of a
conventional paddle wheel, wherein the only reaction is from
pushing on the water, rather than a combination of pushing on the
water and "jetting" the channeled water. The hull is designed to
reduce the likelihood that overfilling will occur. Moreover, by
enclosing the rotating components, aerodynamic drag is reduced. The
top of the propulsion wheel is moving at approximately twice the
speed of the marine vessel and the added impulse speed of the
members 12 would create considerable drag if the components were
exposed. In addition to reducing drag, the fairing reduces noise,
reduces spray, and increases safety.
[0030] An advantage of the invention is that the propulsion system
induces little turbulence. Water is directed in a laminar flow.
Additionally, the "wetted area" is very small, since only one face
of a water-channeling member receives water and since only a
portion of the member is immersed. This provides a control over
surface friction losses. By contrast, a conventional propeller
blade is fully immersed and subject to high surface frictional
losses when translating through the water.
[0031] FIG. 4 is an end view of a tunnel hull 82 as used with a Jet
Ski. A seat portion 84 is attached atop the hull portion. Because
of the design of the tunnel hull, the water level 86 of the marine
vessel is well above the water level 88 presented to the
water-channeling members 12 and 14. As water flows relative to the
vessel, each water-channeling member scoops a "bite" of water,
compresses the water toward the central region of the cavity of the
rearward face, and ejects the accelerated water rearward.
[0032] The tunnel hull of FIG. 4 provides advantages with respect
to safety and to protection of the system. As can be seen, the
marine vessel can pass over a person without a high risk of the
rotating members 12 and 14 injuring the person. Similarly, if the
hull passes over a log or other object, the members 12 and 14 are
not likely to be damaged.
[0033] FIG. 5 illustrates an alternative configuration for the
water-channeling members. In this embodiment, each member 62
comprises a pair of fingers 64 and 66. When the member is connected
to a propulsion wheel and is allowed to extend into water such that
only the ends of the fingers are submerged, water will be received
and channeled upwardly. A curved end 68 has a configuration that
will at least partially determine the thrust characteristics of the
individual member. The overall configuration of the member
determines the increase in velocity of water, while the
configuration of the curved end will play a role in the direction
of applied force. The angle at which the individual member is
mounted to the propulsion wheel will determine the "attack angle"
of the fingers 64 and 66 and will determine an angle at which water
is projected from the curved end 68.
[0034] FIG. 6 is another embodiment of a water-channeling member.
In this embodiment, the member 70 has a blunted water pick up end
72. A greater volume of water is able to be collected. However, as
with the other embodiments, there is a region in which the ingested
water will accelerate, so that water is increased in velocity and
is projected from a curved end 74 having a configuration designed
to achieve desired thrust characteristics.
[0035] Referring again to FIG. 3, the water-channeling members 12
can be shaped and oriented to produce desirable characteristics.
Nominally, the reaction jet 78 may be directed fully rearward for a
maximum thrust. However, aiming the jet downwardly will produce
lift, which may be used to provide levitation of the marine vessel
so as to reduce friction.
[0036] As previously noted, the propulsion system 10 may be
connected to the marine vessel using a suspension system similar in
affect to suspension systems of land vessels. In combination with
providing levitation, the result is that a smoother and more
efficient ride is possible. In the interest of further improving
upon efficiency and performance, the hull is utilized.
Conceptually, the moving components operate by transforming a
section of scooped water into a much smaller cross section or "jet"
of high speed water. The ratio may be roughly 3:1, but other ratios
are considered. When a water-channeling member contacts water at
its tip, the velocity of "x" of the water is ejected at "3x". This
results in a reaction thrust being applied to the propulsion wheel
30 and, therefore, the hull. Any viscous flow losses at the face of
the water-channeling member are exhibited on the propulsion wheel
and consequently the hull. The only undesirable losses acting on
the system are aerodynamic losses on the propulsion wheel at the
top side of its rotary motion. For this reason, it is enclosed
within the shroud.
[0037] The propulsion system may be adapted for use with amphibious
vessels. The rotary drive that powers the rotation of the
propulsion wheel 30 may also power rowing elements that are linked
through or separately from the propulsion wheel. For example, the
rolling element may be a broad rim that is allowed to travel on a
beach when the marine vessel exits the water.
[0038] While the increased efficiency of the propulsion system
relative to conventional systems provides advantages in high speed
applications, recreational applications are also considered. For
example, the rotary drive for powering the propulsion wheel 30 may
be manual, such as the use of a peddling system similar to a
bicycle.
[0039] There are a number of different possible lifting forces. As
speed increases, there is a significant lifting force developed as
water flows upwardly and encounters the compound curved end that
forms the exit jet 78. This forces the water-channeling member 12
both forward and upward. The upward force helps support the weight
of the marine vessel. If the members 12 are properly angled and
sufficient speed is generated, there may be conditions in which the
vessel is fully supported, eliminating contact with the water and
therefore eliminating drag which would otherwise result from
viscous shear of the hull against the surface of the water. At this
point, aerodynamic drag and gravitation would be in equilibrium
with the forces generated by the propulsion system, and normal
aquatic speed restrictions would be substantially reduced.
[0040] In some applications, the fairing or hull for the propulsion
system is the marine vessel itself, as is the case in the
embodiment of FIG. 4. However, in other applications, the hull can
provide floatation as well as desired stationary stability. It is
possible to connect the propulsion system in a hollow watertight
hull that is attached to the marine vessel using a suspension
system that enables movement relative to the marine vessel. That
is, the hull is able to adjust with waves and other changes in the
water level of the main body of water. For example, where two
propulsion systems are used to power a boat, two hulls may be
connected to the boat in an "outrigger" manner. In many
applications of the invention, the suspension should be at the very
front of the marine vessel, so as to help support the bow from
dipping into the water trough, only to nose into the next wave
crest. If propulsion pads are used to follow these undulations
while tractoring up and down the wave faces, a much more consistent
motive force can be obtained.
[0041] From the foregoing, it is apparent that the invention
operates on inertial mechanisms in which water is in contact with a
"cupped" member only on its compression side. The system "slings"
water at accelerated speeds as an efficient reaction jet mechanism
with minimal lossy contact with the water being ejected. Convention
paddle boats work primarily on viscous drag principles, while
propellers work on lifting body (wing) principles. Water jets work
primarily on pumping/ejection principles. The present invention
controls losses associated with all of these mechanisms, such as
tip vortexes, cavitation, turbulent flow, and compressibility/flow
issues.
* * * * *