U.S. patent number 3,598,402 [Application Number 04/741,473] was granted by the patent office on 1971-08-10 for appliance for practicing aquatic sports.
Invention is credited to Otto Frenzl.
United States Patent |
3,598,402 |
Frenzl |
August 10, 1971 |
APPLIANCE FOR PRACTICING AQUATIC SPORTS
Abstract
An appliance for the practicing within a reduced area of aquatic
sports such as surf-riding and water-skiing, said appliance
including a vat the bottom of which is sloping and has a
longitudinal section which shows a concavity facing upwards while a
stream of water is caused to flow upslope over said bottom as
produced by a nozzle discharging water onto the surface of the
lower end of said bottom.
Inventors: |
Frenzl; Otto (77
Dammarie-Les-Lys, FR) |
Family
ID: |
8636841 |
Appl.
No.: |
04/741,473 |
Filed: |
July 1, 1968 |
Foreign Application Priority Data
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Aug 11, 1967 [FR] |
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117,810 |
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Current U.S.
Class: |
482/71; 4/496;
73/148; 434/253 |
Current CPC
Class: |
B63B
32/00 (20200201); A63C 19/10 (20130101); A63B
69/0093 (20130101); A63B 69/125 (20130101); A63B
69/187 (20130101) |
Current International
Class: |
A63B
69/18 (20060101); A63B 69/00 (20060101); A63B
69/12 (20060101); A63C 19/00 (20060101); A63C
19/10 (20060101); B63B 35/73 (20060101); A63g
031/16 () |
Field of
Search: |
;272/17,16,18,1B,1,26,71,72,8,8N,57B ;35/29 ;73/148 ;4/172 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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681,070 |
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Feb 1964 |
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CA |
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831,333 |
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Feb 1952 |
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DT |
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1,118,083 |
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Jun 1968 |
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GB |
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Primary Examiner: Oechsle; Anton O.
Assistant Examiner: Kramer; Arnold W.
Claims
I claim:
1. A surf-riding and water-skiing simulating and training
appliance, comprising:
an enclosure including a fixed bottom surface which slopes upwardly
with reference to a horizontal plane for accommodating a
surf-riding or water-skiing trainee wearing a surfboard or water
skis; and
means for constraining a shallow stream of water to flow upslope
over said bottom surface under steady flow conditions and at a
velocity higher than ge, e being the depth of the stream and g the
constant of gravity acceleration for supporting the trainee facing
downslope in a surf-riding or water-skiing stance on said board or
skis, whereby to enable said trainee to retain a stable equilibrium
position under the influence of a first, upslope directed force
ascribable to the drag of said board or skis dipped in said
high-velocity stream, and of a second, downslope-directed force
ascribable to the component of the weight of the trainee in a
direction parallel to said sloping bottom surface.
2. An appliance as claimed in claim 1, wherein the longitudinal
section, with reference to the general direction of flow of the
stream of water, of said bottom surface is a curve having a
concavity facing upwards at least over the major part of its
length.
3. An appliance as claimed in claim 1, further comprising means
hingedly supporting said fixed bottom surface about a substantially
horizontal axis transversely directed, with reference to the
general direction of flow of the stream of water, and means for
tilting said bottom surface about said axis to an adjustable
extent, whereby to adjust the slope of said fixed bottom surface to
a predetermined value.
4. An appliance as claimed in claim 1, wherein the means
constraining a stream of water to flow under steady flow conditions
over said upwardly sloping fixed bottom surface include at least
one nozzle means adapted to steadily discharge a jet of water onto
said bottom surface in the vicinity of a lower region of said
surface and in the direction of a higher region of said
surface.
5. An appliance is claimed in claim 4, further comprising means for
adjusting the cross-sectional area of said nozzle means to a
predetermined value.
6. An appliance as claimed in claim 1 wherein said enclosure,
further comprises sidewall means bounding a vat means the bottom of
which is formed by said bottom surface.
7. An appliance is claimed in claim 6, wherein the means
constraining a stream of water to flow under steady flow conditions
over the said upwardly sloping bottom surface of said vat means
include a return pipe means and means for bringing about a steady
recirculation of water through a circuit including said bottom
surface and said return pipe means.
8. An appliance as claimed in claim 7, wherein said return pipe
means form with said vat means an integral unit including said
circuit, said appliance further comprising means hingedly
supporting said unit around a substantially horizontal transverse
axis, and means for tilting said unit about said axis to an
adjustable extent, whereby to adjust the slope of the fixed bottom
surface of said vat means, to a predetermined value.
9. An appliance as claimed in claim 7, further comprising water
storage means integral with said vat means, means connecting said
storage means with said circuit, said connecting means comprising
valve means and pump means, whereby water may be pumped from said
storage means and sent into the circuit, and conversely.
10. An appliance as claimed in claim 1, wherein the means
constraining a stream of water to flow under steady flow conditions
over said upwardly sloping bottom surface include a return pipe
means and means for bringing about a steady recirculation of water
through a circuit including said bottom surface and said return
pipe means.
11. An appliance as claimed in claim 10, wherein the means for
bringing about a steady recirculation of water comprises a pump
means and a power unit for driving said pump means.
12. An appliance as claimed in claim 11, wherein said power unit
comprises a hydraulic engine.
13. An appliance as claimed in claim 11, wherein said power unit
comprises a heat engine, said appliance further comprising heat
exchanger means for transferring the lost heat from said engine to
the water of said circuit.
14. An appliance as claimed in claim 10, erected near a waterfall,
wherein the means for bringing about a steady recirculation of
water comprise a pump means, a hydraulic engine for driving said
pump, and means wherethrough the hydraulic engine is driven by the
head of water corresponding to said waterfall.
15. An appliance as claimed in claim 10, wherein the means for
bringing about a steady recirculation of water comprise an ejector
pump means, and means for supplying said ejector pump means with an
inducing stream of water.
16. An appliance as claimed in claim 10, erected near a waterfall,
wherein the means for bringing about a steady recirculation of
water comprise an ejector pump means, and means for supplying said
ejector pump means with an inducing stream of water with a head
corresponding to said waterfall.
17. An appliance as claimed in claim 1, wherein the means
constraining a stream of water to flow under steady flow conditions
over said upwardly sloping fixed bottom surface include a body of
water having a water level which is higher than the upper end of
said bottom surface, and means continuously connecting said body of
water with a lower region of said bottom surface.
18. An appliance as claimed in claim 1, erected near a waterfall
which extends between a first body of water with a relatively
higher water level and a second body of water with a relatively
lower water level, wherein the means constraining a stream of water
to flow under steady flow conditions over said upwardly sloping
fixed bottom surface comprise means continuously connecting said
first body of water with a lower region of said bottom surface, and
means continuously connecting said second body of water with an
upper region of said bottom surface.
Description
My invention covers an appliance for practicing nautical sports,
said appliance comprising a vat closed at its lower end by a bottom
over which water is constrained to flow as a stream showing a free
upper surface along which it is possible to practice an aquatic
sport within the restricted space constituted by the vat.
A number of appliances are known, which allow for instance
practicing swimming and sometimes, with a more speedy flow of
water, water-skiing.
They do not allow, in contradistinction, practicing a novel sport
which is now increasingly popular and which is known as
surf-riding. Such a sport is practiced in the vicinity of a reduced
number of beaches where billows of an adequate shape break, the
devotees of surf-riding being carried along on a board or the like
part sliding over the slope of the billows in a manner such that
the sliding movement of the board combined with the substantially
vertical movement of said board due to the surge finally results in
a shifting of the surf-rider in parallelism with the free surface
of the water.
All such known arrangements have furthermore a reduced efficiency
by reason of the fact that the major part of the kinetic energy of
the water which has not been made use of by the water skier or the
like is lost.
SUMMARY AND OBJECTS OF THE INVENTION
My invention has for its object to afford means for practicing in
all seasons within a reduced space and in an economical manner, not
only swimming or water-skiing, but also surf-riding and a further
sport which has not been practiced hitherto and consisting in being
carried by two boards as in the case of water-skiing while
maintaining one's balance in accordance with the principle of
surf-riding, this corresponding to water-skiing with one's hands
free. My invention has also for its object to allow gradually
turning from the comparatively easy practicing of water-skiing
under control of a pulling cable to the more difficult practicing
of water-skiing with one's hands free or of surf-riding, so as to
further under conditions readily available for the general public
physical development and individual skill.
According to my invention, the bottom of the vat inside which an
aquatic sport is to be practiced slopes with reference to a
horizontal plane in a manner such that water may flow over said
bottom upslope, that is in an upward direction.
Such an arrangement shows firstly the advantage of allowing the
practicing of surf-riding and other similar sports, as the sloping
of the vat bottom results in the possibility for the water skier to
keep his balance in an equilibrium position depending, on the one
hand, on an upwardly directed force ascribable to the drag or
resistance of the carrier board or boards dipped into the stream of
water and, on the other hand, on a downwardly directed force
produced by the component of the weight of the water skier in a
direction parallel with the vat bottom.
My invention shows also the advantage of allowing the recovery as
potential energy of the major fraction of the kinetic energy
applied to the stream of water and which, in fact, is finally not
used by the water skier. Said water being generally recirculated
for instance by a pump system, the power required for recirculating
the water is considerably reduced.
According to a preferred embodiment, the sloping bottom of the vat
is not flat, but incurved in longitudinal section, with concavity
facing upwards.
A theoretical and experimental investigation of the appliance has
shown as a matter of fact that the position of equilibrium of the
user as referred to hereinabove may, under certain conditions, lack
stability. It may occur, during operation, that the user changes
suddenly the position of the board or boards carrying him with
reference to the water surface, for instance when he simulates
sudden movements such as turns, side slips, snow ploughs or the
like. This may lead to a substantial alteration of the upwardly
directed force referred to thereinabove and thereby either to a
sudden sinking of the water skier whose weight has thus become
suddenly predominant down to the lower end of the bottom or else in
the opposite case, to a rising of the water skier into immediate
proximity with the upper end of said bottom.
It has been found that the concavity in the longitudinal section of
the bottom of the vat cooperates in a positive manner in ensuring
stability by introducing into the equation defining the position of
equilibrium referred to hereinabove a stabilizing factor
constituted by the gradual variation along said longitudinal
section of the component of the weight of the water skier along a
parallel to the surface of said bottom.
According to a particularly advantageous feature of my invention
the vat bottom is pivotally mounted around a substantially
horizontal axis, so that its slope may be adjusted. This pivotal
fitting allows, as will be readily ascertained, adjusting within a
broad range the conditions of flow of the water over the bottom and
in particular its speed and depth, so that the appliance may be
adjusted for that sport which has been selected for practice. It is
possible, for instance, to practise ordinary water-skiing by
selecting a reduced slope for the bottom. For the practicing of
water skiing with one's hands free or of surf-riding, in
contradistinction, a steep slope should be used.
The stream of water used should generally be of the so-called
torrential type, except for swimming purposes. It will be reminded
that the expression "torrential flow" is opposed to the so-called
river flow as well known for anyone studying the flow of water
under free surface conditions. In the case of a torrential flow,
the speed V of the water is higher than a critical speed Vc which
is equal to the celerity of propogation in the flow of an
infinitely small wave termed sometimes a translational wave. The
value of Vc for a flow over a depth e is equal to ge, g being the
constant of gravity acceleration.
It is possible to use in practice a nozzle discharging onto the
sloping bottom of the vat a stream of water having a reduced depth
e at a speed V which is clearly higher than the critical value Vc
referred to and showing consequently the properties of a torrential
flow ; the operation of the appliance can be started with a reduced
slope of the bottom, which slope is then gradually increased. The
starting may also be performed through a sudden opening of the
nozzle.
As a modification, it is possible to bring about a stream of a
comparatively large depth of the so-called river type which allows
practicing swimming, the speed of said stream being lower than the
critical value Vc referred to and being selected in conformity with
the speed of the swimmer.
The following description and corresponding accompanying drawings
are given by way of an example and in a nonlimiting sense so as to
afford a proper understanding of the invention. In said drawings
:
DESCRIPTION OF THE DRAWINGS
FIG. 1 illustrates cross-sectionally through line I-I of FIG. 2 an
appliance for practicing aquatic sports according to my invention
;
FIGS. 2a and 2b shows the arrangement illustrated in FIG. 1,
respectively as seen from above and cross-sectionally through line
II-II of FIG. 1;
FIG. 3 is a plan view of a board or similar sliding support ;
FIG. 4 is a cross section of FIG. 3 through line IV-IV of the
latter ;
FIG. 5 illustrates diagrammatically a further embodiment of an
appliance according to my invention ;
FIG. 6 illustrates the appliance according to FIG. 5 when assuming
a sloping position ;
FIG. 7 is a cross-sectional view of a third embodiment of my
invention ;
FIG. 7bis a diagrammatic explanatory view of a portion of FIG. 7
;
FIG. 8 is a diagrammatic sectional view of a modification of the
means feeding water into an appliance according to my
invention.
DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION
Turning now to FIGS. 1, 2a and 2b, my improved arrangement includes
a vat with a bottom 1 adapted to pivot round a transverse axis 12
and a nozzle 2 adapted to discharge water onto the surface of said
bottom 1, so as to form a stream having a depth e, the line
carrying the reference number 3 defining the free surface of the
stream.
The speed of the stream of water thus produced is sufficiently
high, taking into account the depth e, for the flow to be of the
torrential type referred to hereinabove. As may be ascertained from
inspection of FIG. 1, the upper surface of the bottom 1 slopes with
reference to a horizontal plane and consequently the speed of the
stream of water diminishes as the water rises along said bottom
surface, so that the depth e of the stream of water increases
gradually as it is considered further from the nozzle 2.
The depth of water may also be caused to increase suddenly in the
vicinity of the upper section of the vat bottom, thereby forming a
jump beyond which the flow becomes a river-type flow, the level of
the free surface of the water in said downstream area being
illustrated by the line 4.
It should also be remarked that the longitudinal section of the
bottom 1 is incurved and has its concavity facing upwards.
The water stream is circulated back to the nozzle 2 in a closed
circuit which in the example illustrated includes elongated slots 5
formed longitudinally at the upper end of the sloping bottom,
bellows 6 underneath said slot, a chamber 7 and a return channel 8.
The water flows in said circuit under the action of a pumping
system constituted in the case illustrated by two propellers 9
driven by one or more power units 13.
Sidewalls 10 which are preferably inflatable are associated with
the bottom 1 to form a complete vat adapted to be adjustably tilted
round the pivotal axis 12. To this end, a jack 11 engages on the
one hand the sloping bottom 1 and on the other hand a stationary
frame. As illustrated in FIG. 1, the sloping bottom 1 is in its
medial position while the extreme positions of the sloping bottom
are illustrated by the short lines at a and at c.
The reference number 14 designates the anchoring means for
skier-retaining cables 18 and the reference number 15 designates
instruments giving out the speed of the stream of water at the
outlet of the nozzle 2 and the actual position of the sloping
bottom.
One or two sliding surfaces constituted for instance by boards 16
which are well known per se and are illustrated in FIGS. 3 and 4
allow simulating all the stages of water-skiing between low speed
and full speed, upon setting of the sloping bottom 1 in a position
lying between the horizontal position a and the position
illustrated at b. The water skier is then held in position by the
cables 18.
Steeper slopes, lying between the position b illustrated and the
position defined by the line c provide a transition towards
water-skiing with one's hands free or towards surf-riding. The
sliding surface or surfaces 16 are preferably provided with lateral
walls 20 also known per se but of a larger size than hitherto so as
to bound between the vat bottom 1 and the sliding surface 16 a
water cushion according to the ground effect principles.
It is then possible for the water skier not only to keep his
balance without resorting to the retaining cables 18 and by relying
solely on the movements of his center of gravity, but furthermore
he can modify the slope of the board or boards or the like sliding
surfaces 16 so as to find those points near the nozzle where the
speed of the water is higher or else water levels located further
from the nozzle 2 and where the speed of the water is lower and the
depth is larger.
FIG. 7bis shows how the surf rider lying over a sliding board may,
by engaging his feet more or less deep into the water, vary his own
drag or resistance in the stream, whereby he may change his
position to a large extent and simulate thus the practicing of a
sport similar to toboganning.
One or more transverse cables 19 serve as safety means preventing
the water skier or surf rider from coming too near the nozzle
2.
In the arrangement illustrated for the practice of surf-riding or
water-skiing, the speed of the stream of water is higher than the
speed Vc = ge as defined hereinabove, so that the flow is actually
of the torrential type.
The appliance according to the invention allows also practicing
swimming. To this end, the swimmer sets the bottom 1 into a
slightly sloping position i.e. that illustrated at a and he fills
the vat almost up to its upper edge. He resorts then to low speeds
for the water stream, which stream is smoothed out by one or more
grids 17 constituted for instance by perforated plates, nets or the
like.
The speed of the stream of water may be adjusted, so as to match
the speed of the swimmer, by acting on said grids or on the power
unit 13 or again by partly covering or uncovering the slots 5 or by
varying the depth of the stream or again by simultaneously acting
on two or more of such adjusting means; in such a case the speed of
the stream beyond the grids 17 drops underneath the critical speed
V.sub.c, the stream being then of the river flow type.
In the embodiment illustrated diagrammatically in FIGS. 5 and 6
those parts which are the same as those already described and
illustrated in the preceding figures are designated by the same
reference numbers. The slope of the bottom surface 1 may be
controlled by tilting the entire appliance round an axis 12a by
means of jack 11a ; inside the vat founded by the sidewalls 10,
storage compartments 21 may be formed, which compartments
communicate with the vat proper through a channel 23, a pump 22 and
a stopcock 24.
The arrangement includes as in the preceding embodiment a return
channel 8, safety cables 19 and a nozzle 2. The position of the
appliance as illustrated in FIG. 5 is that which may be used for
swimming. The bottom is substantially horizontal, while the grids
17 are operatively positioned. The water is pumped out of the
storage compartments 21 by the pump 22 and sent into the circuit,
which produces a rising of the water level in the vat. It is also
possible to use instead of the pump 22 the recirculation pump 9
provided the channel 23 is connected with a point of the circuit
where the speed of flow is high.
In this last embodiment, the slope of a flap 25 closing the upper
end of the nozzle 2 is adjustable so as to allow a sufficient flow
rate of water to flow under low-speed conditions.
The position of the appliance as illustrated in FIG. 6 is that
which is suitable for water-skiing or surf-riding. In this case,
the compartments 21 are filled with water in a manner such that the
depth of the stream of water may be reduced while the bottom is
caused to slope by a tilting of the whole appliance and the grids
17 are dismantled.
In the embodiments illustrated in FIGS. 1 to 6, the means 9--13
urging the water into circulation require a comparatively low power
which may even not be sufficient for the starting of said
circulation when the bottom 1 is in a steeply sloping position. In
such a case, the starting is performed by giving first a reduced
slope to the bottom 1, for setting the water in motion, the water
continuing its circulation when the slope of the bottom is
gradually increased.
The embodiment illustrated in FIG. 7 relates more particularly to a
large-scale appliance adapted for instance to be used in public
baths. This arrangement includes a stationary vat 27 bounded by
sidewalls 10 and by a sloping bottom 1 ; as in the preceding
embodiments, said bottom is concave upward.
A discharge nozzle 2 may be closed by a pivoting flap 25 the closed
position of which is illustrated in FIG. 7 in dotted lines.
The vat 27 is adjacent a tank 36 lying at a higher level than said
vat and filled with water up to a level 31. Said tank may be
constituted for instance by a swimming pool.
The appliance is started operating as follows ;
The vat 27 is assumed to have been drained by means disclosed
hereinafter, and the channel 8 is supposed to be closed by a flap
valve 26 as illustrated in dotted lines. The motor 13 is then
started, so as to drive the pump 9, and the nozzle 2 is speedily
opened. A powerful stream of water flows during a short time out of
the tank 36 and enters the slots 5. Under the head of water thus
built up in addition to that supplied by the pump 9, the flap valve
26 opens and the water is started circulating.
The speedy opening and closing of the nozzle 2 are controlled in
the example illustrated by a further flap valve 32 which connects a
chamber 33 lying above the pivoting flap 25 closing the nozzle 2
selectively with a low-pressure area such as that 34 provided for
the draining of the water and with a high-pressure area such as the
tank 36 through the port 35.
The draining of the vat 27 is performed by means of a channel 28
and a sluice 29. It is possible, as a modification, to resort to a
pump 30 delivering water into a channel 37 which allows returning
water into the tank 36.
In all the embodiments disclosed, the water is somewhat heated as a
consequence of a partial dissipation of the energy supplied to the
pump.
In the case where the power unit is a heat engine, it is possible
to use the heat carried by the cooling circuit of the engine and/or
the heat of the exhaust gases for heating the water. Such an
arrangement has been illustrated diagrammatically in FIG. 1, which
shows a heat exchanger 40 fed by the exhaust gases from the engine
13.
The appliance for aquatic sports according to my invention may also
be set up in transverse registry with a section of a natural stream
of water showing a waterfall. If the flow rate of said stream is
sufficient for feeding the nozzle 2, the recirculating means
described with reference to FIG. 7 and consequently the parts 9,
13, 26 are no longer necessary. The head of the waterfall should be
at least equal to the difference in level between the free surfaces
31 and 4. If the head of the waterfall is greater than the
above-mentioned difference in level while in contradistinction the
flow rate of the stream is lower than that which should normally
pass though the nozzle 2, it is possible to resort to a fraction of
the energy produced by said fall with a view to recirculating the
water through the return channel 8.
The power unit 13 of FIG. 7 may then be constituted by a hydraulic
engine such as a turbine driving the pump 9 under the action of the
head of water between the water levels at 31 and at 4. I have
illustrated diagrammatically at 41 and 42 pipes for the admission
of water into and the exhaust of water out of such a turbine. The
mechanical pump system 9--13 may also be replaced by an ejector
pump of a simpler design, as illustrated diagrammatically in FIG. 8
wherein the reference number 43 designates a pipe through which an
inducing stream of water is introduced into channel 8 with a head
corresponding to the waterfall.
My improved appliance for aquatic sports requires a low driving
power since the raising of the water upslope over the bottom 1
results in the conversion of a large fraction of the kinetic energy
of said water into potential energy and this leads to an increase
in pressure ahead of the pump 9.
The driving power serves merely in fact as a compensation for the
losses inside the water circuit in addition to those ascribable to
the presence of the water skier.
A further advantage resides in the comparatively small bulk of the
appliance and in the reduced amount of water required, which
furthers in particular the heating and purifying of said water. The
appliance may be readily fitted in a house so as to allow
practicing aquatic sports throughout the year. Beginners may be
given all possible facilities such as large sliding boards, reduced
water speed and low slope of the bottom, retaining cables and the
like.
As to skilled water skiers and the like, difficult and varied
programs may be proposed to them, involving the use of small
sliding boards, together with great water speeds and steeply
sloping bottom surfaces for the vat, while the opening of the
nozzle 2 may be subjected to speedy modifications and the retaining
cables may be done away with and so on.
Obviously the embodiments described have been given out solely by
way of examples and it is possible to modify them chiefly by
substituting technical equivalents for the parts disclosed, without
widening thereby the scope of the invention as defined by the
accompanying claims.
* * * * *