Float type wave energy extraction apparatus and method

An apparatus and method of obtaining useful energy from wave action in a body of water. The apparatus comprises a cylinder, a reciprocal piston in the cylinder, a piston rod connected to the piston and extending sealably out of the cylinder, a mechanical tensioning device connected between the piston and the cylinder for maintaining resilient tension between the piston and the cylinder, a float connected to one of the piston rod or the cylinder, an anchor flexibly connected to the other of the piston rod or the cylinder which is not connected to the float, an inlet check valve and an outlet check valve connected to the cylinder, and a conduit extending from the outlet check to an area where water may be usefully employed. The mechanical tensioning device may be a spring or a weight and tether. The apparatus and method may be used to operate a hydroelectric generator.

BACKGROUND OF THE INVENTION 
This invention relates to devices which extract energy from wave action in 
a body of water. More particularly it concerns the extraction of energy 
from wave action utilizing a float, a piston-cylinder pump, and an anchor. 
Various types of devices which attempt to extract energy from wave action 
in a body of water or from the wind have been known for some time. For 
example, U.S. Pat. No. 4,421,461 issued to Hicks et al. discloses a water 
wave-powered piston pump. The piston pump is mounted on a cradle. The 
cradle consists of two plates, an upper plate and lower plate. The upper 
side of the upper plate is secured through a sacrificial link to the float 
on the upper side and the lower side of the upper plate is secured via a 
yoke to the pump piston rod which extends out the bottom of the cylinder. 
The upper side of the lower plate of the cradle is attached to the bottom 
of the pump cylinder and the lower side of the lower plate is attached to 
the anchor via a flexible tether. A multiplicity of circumferentially 
spaced elastomeric springs surround the cylinder of the pump externally to 
the cylinder. The springs are connected between the upper plate and lower 
plate of the cradle. A polymeric ball is supported in the upper face of 
the piston and retained therein by a compression spring biased lock plate. 
As the float rises the compression spring inside the pump cylinder is 
compressed which compresses the polymeric ball between the spring biased 
lock plate and the piston. The polymeric ball expands radially due to the 
compression and seals the cylinder against leakage past the piston. Also, 
as the pump rises the multiplicity of circumferentially spaced elastomeric 
springs external to the cylinder are stretched and are used as external 
return springs which impel the pump piston rod on its down or refill 
stroke as the float falls on a wave. 
U.S. Pat. No. 4,398,095 issued to Ono discloses a wave-activated power 
generation system of the float type. A piston-cylinder type pump is 
anchored to the bottom of a body of water and the float is connected to 
the piston. As the float rises on a wave the piston is lifted and water is 
discharged from the pump into an elevated reservoir. Ono uses the 
hydraulic differential pressure between the air at the surface of the body 
of water and the depth of the piston cylinder pump in the body of water to 
move the piston downwardly in the cylinder as the float falls with a 
descending wave. Because of this use of hydraulic pressure rather than 
resilient tension between the float and the anchor the Ono device is 
solidly supported from the bottom of the body of water in order to resist 
the downward hydraulic pressure. Therefore the bottom of the body of water 
must be accessible, which either limits the depth of water in which the 
Ono system can be used or requires additional, expensive equipment to 
position and maintain the system. 
U.S. Pat. No. 4,104,006 issued to Meiri discloses a wind-powered energy 
conversion device. The device includes a pair of flaps which are connected 
to the piston of a piston-cylinder type pump by cable. A tension spring is 
connected between the piston and the platform upon which the piston pump 
is mounted. As wind lifts the flaps the cable pulls the piston upwardly 
and stretches the spring. When the wind decreases the spring pulls the 
piston back down. The Meiri device does not use or require a float and is 
rigidly mounted to the platform or ground. 
A drawback to the prior wave energy extraction devices is that they are 
relatively complex and expensive to maintain and manufacture. Since one of 
the main purposes of developing wave energy extraction devices is to 
reduce the cost of energy, the costs involved in maintaining and the 
manufacturing the wave energy extraction devices is a very important 
factor in the practicability of the devices. Thus, there is a need in the 
art for a wave energy extraction device which is inexpensive to 
manufacture and maintain. 
SUMMARY OF THE INVENTION 
It is an object of this invention to provide a wave energy extraction 
apparatus which is inexpensive to maintain and manufacture, even to the 
point of being expendable, that is, if the device becomes inoperative it 
can simply be replaced. The invention achieved this object by connecting a 
mechanical tensioning means, such as a tension spring or weight and 
tether, between the piston and cylinder of a piston-cylinder pump which is 
reciprocable and flexibly connected between a float and an anchor in a 
body of water. This previously unknown combination creates a wave energy 
extraction apparatus of previously unachievable simplicity and economy 
which can be used in virtually any depth of water. 
It is also an object of this invention to provide a wave energy extraction 
apparatus in which part of the energy generated by the wave lifting the 
float, is transferred to a temporary energy storage means such as a spring 
or moving weight, so that part of the original energy imparted to the 
float is given back into the system as the float returns to its lower 
position. 
Accordingly the wave energy extraction apparatus of the present invention 
includes a reciprocating pump flexibly connected between a float and an 
anchor. The pump includes a cylinder having a top end and a bottom end 
with a reciprocal piston in the cylinder. The piston has a piston rod 
connected to it which extends out the bottom of the cylinder. The anchor 
is flexibly connected to the outside end of the piston rod and anchors the 
piston rod relative to the cylinder. The float is connected to the 
cylinder and upstrokes the cylinder relative to the piston in response to 
a rising wave action. A mechanical tensioning means is mechanically 
connected between the cylinder and piston for maintaining resilient 
tension between the piston and cylinder. In one form the mechanical 
tensioning means is a tension spring which is mechanically connected 
between the cylinder and piston. In another form the mechanical tensioning 
means is a weight and tether. The tether extends from a fast connection 
with the piston through a slidable connection with the cylinder to a fast 
connection with the weight. The slidable connection of the tether to the 
cylinder may be a simple pulley. An inlet check valve and an outlet check 
valve are connected to the cylinder. As the float rises in response to a 
rising wave action the upstroking cylinder expels water through the outlet 
check valve. As the float falls in response to falling wave action the 
mechanical tensioning means downstrokes the cylinder relative to the 
piston and draws water into the cylinder through the inlet check valve. A 
conduit may be connected to the outlet check valve and extended to an area 
where the pump water may be usefully employed such as for generating 
electricity. 
In another embodiment of the present invention the piston rod extends 
sealably out the top end of the cylinder. The float is connected to the 
outer end of the piston rod and the anchor is flexibly connected to the 
cylinder. The mechanical tensioning means is mechanically connected 
between the cylinder and the piston as previously discussed. In one form, 
the mechanical tensioning means is a tension spring which is mechanically 
connected between the cylinder and the piston, and in another form the 
mechanical tensioning means is a weight and tether. The tether extends 
from a fast connection with the cylinder through a slidable connection 
with the piston to a fast connection with the weight. In this embodiment, 
as the float rises in response to a rising wave action the float upstrokes 
the piston relative to the cylinder and expels water through the outlet 
check valve. As the float falls in response to a falling wave action the 
mechanical tensioning means downstrokes the piston relative to the 
cylinder and thereby draws water into the cylinder through the inlet check 
valve. 
It is an advantage of the present invention to provide a simple, 
inexpensive wave energy extraction apparatus which may include, 
insequence, a float connected to a piston or cylinder, a single tensile 
spring or a single weight and tether connected between the piston and 
cylinder, and an anchor flexibly connected to the one of the piston or 
cylinder to which the float is not connected. The apparatus is extremely 
simple in concept, operation, and maintenance, may be inexpensibly 
constructed of styrofoam and polymer, and thus is expendable. If 
maintenance is performed on the apparatus it is simple and straight 
forward because of the simplicity of the device itself. 
It is another advantage of the present invention to provide automatic 
adjustment for variations in the depth of the body of water, such as are 
caused by changes in tide.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings and in particular to FIG. 1 there is 
illustrated schematically one embodiment of this invention. The entire 
system is indicated generally by the numeral 10. It comprises a float 
system indicated generally by the numeral 12 floating on the water surface 
or wave surface 14 of the sea 16. A flexible tension means or tether 18 
ties the float to a pump system 20 comprising a cylinder 22 and a piston 
30. An energy storage means such as a mechanical spring 34 is interposed 
between the cylinder 22 and the piston 30. The compliance, or compliant 
means 34 is tied to the cylinder at point 33 and to the piston at point 
31. This could, of course, be positioned outside of the cylinder if 
desired. For example, it could be connected between the outside of the 
cylinder 22 and piston rod 32. A conventional stuffing box 24 may be used 
to pass the piston rod 32. The conventional check valves 26 and 28 would 
of course be required. 
The compliant means, or compliance, or spring 34 is an energy storage 
means. This accepts energy from the float (as the float rises, stretching 
the spring) and gives it up again as the float drops. 
Its purposes are several: 
1. it permits extending the length of the tether as the tide raises the 
entire water surface, permitting the float to ride the top of the waves; 
2. it maintains the tether in tension so that its action on the piston is 
like a rigid "pusher". Since the flexible tether can't push on the piston 
to move it up into the cylinder as the float lowers, the spring pulls it 
into the cylinder (and also draws liquid into the cylinder); 
3. it makes the flexible tether system work like the rigid tether system, 
but is simpler and cheaper than the rigid system, and can be quickly 
adjusted for any depth of water. 
Another method of energy storage will be described in connection with FIG. 
4. This involves a flexible cable 92 attached to the top of the piston at 
31. The cable 92 passes over a pulley 91 mounted on a support 90 attached 
to the float, and down through a passageway (or pipe) 94 to a weight 93 of 
selected mass. The tension in the cable 92 serves the same purpose as the 
tension in the spring 34, that is, both the spring 34 and the weight and 
cable maintain a resilient tension between the piston 30 and cylinder 22, 
except that the cable 92 provides a constant force rather than a variable 
force. Also the tension in cable 92 can be changed readily by changing 
weight 93. 
FIG. 2 is a duplicate of the system of FIG. 1 except that the float is now 
tied to the piston rod through tension means 18 and the cylinder 22A is 
tied to the anchor means through tension means 18A. All parts are 
correspondingly numbered to FIG. 1. To be more specific, the example of 
FIG. 2 provides an apparatus for pumping water using energy from wave 
action in a body of water, comprising: a cylinder 22A closed at the bottom 
end and having an opening 24A at the top end; a reciprocal piston 30A in 
said cylinder 22A; an inlet and an outlet in said cylinder; and an inlet 
check valve 26A in communication with said inlet and an outlet check valve 
28A in communication with said outlet. A pipeline (not illustrated) may be 
connected with said outlet check valve 28A and extended to an area where 
pumped water may be usefully employed. The apparatus of FIG. 2 also 
comprises: a piston rod 32A affixed to said piston 30A and extending 
sealably out said opening 24A in the top of said cylinder 22A; an anchor 
means (not illustrated) affixed to said cylinder; a float means (not 
illustrated) affixed to said piston rod 32A exteriorly of said cylinder 
whereby said piston 30A is reciprocated relative to said cylinder 22A in 
response to wave motion; and a tension spring 34A within said cylinder and 
extending between the interior bottom of said cylinder and said piston the 
said spring maintaining said float under downward tension at all times. In 
the apparatus of FIG. 2 the float means is connected to said piston rod 
32A by a cable, or tether, 18. Also, in the apparatus of FIG. 2, the 
anchor means is connected to said cylinder 22A by a cable, or tether, 18A. 
Another variation of FIG. 1 is shown in FIG. 3. This would be to place the 
cylinder 22B and compliance 34B within the float 12B. This system is 
indicated generally by the numeral 40. A vertical extension 19 to the 
float would be helpful to encase the compliance or spring 34B. The spring 
is attached at its top end at point 33B, and at the piston at point 31B. 
The piston 30B has a piston rod 32B which extends through the packing 
gland 24B to the tension member 18B which ties the piston to the anchor 36 
on the sea floor 38. 
It will be clear as shown in FIGS. 1, 2, and 3 that the cylinders must be 
provided with conventional check valves at inlet and out, as is well known 
in the art. Also the cylinder can be attached to the float as in FIGS. 1 
and 3, or to the anchor as shown in FIG. 2. 
In FIG. 3, the space above the piston identified as 23 is shown as a closed 
volume. If this space is filled with air, it will act as a compliance in 
opposition to the spring. This problem can be overcome in several ways. 
For example, the volume 23 can be enlarged to include all the volume in 
the float by means of opening 25 in the top of the cylinder wall. Another 
way to handle the problem would be to open the top of the cylinder to the 
atmosphere by means of the valve 21, for example. 
There are also a number of ways to store energy, as are well known. One of 
the simplest is to store energy as potential energy in a compressed 
compliance, such as a compressed gas, or compressed (or extended) spring. 
The other is to store energy as potential energy of a mass raised above 
the earth. FIGS. 1, 2 and 3 have illustrated the energy storage in the 
form of a compressed (or extended spring). The other is illustrated in 
FIG. 4. 
Referring now to FIG. 4, a float 12C, cylinder 22C, piston 30C, with tether 
18G and anchor 36 are similar to those in FIG. 3. However, the spring 34 
is replaced by the flexible tension means or cable 92 attached to the 
piston at 31, which passes upwardly and over the pulley 91 supported on 
post 90 to the float 12C. The cable 92 then passes down through an open 
passageway (which may be a pipe sealed into the float) to a weight 93. As 
the float rises, the piston stays fixed in elevation, and the weight rises 
at twice the rate of the float, and liquid is expelled from the bottom end 
of the cylinder. As the wave lowers, the float lowers, and the piston is 
held up by the cable 92, in effect moving it up into the cylinder and 
drawing new liquid into the cylinder. 
Another embodiment using the pump comprising a cylinder and a piston as the 
power extraction means is illustrated in FIG. 5. Here there are two 
sub-systems, the first comprising a float 60 with tension member 18D tied 
to the float. A second sub-system provides a float 60A with tension 
members 18F tied to the float. These two float systems are schematically 
identical. The two floats are separated by a horizontal distance D which 
is approximately one-half of the wave length of the surface waves measured 
along a direction perpendicular to the wave front. Thus, the two floats 
will be operating in an up and down motion 180 degrees out of phase. 
The tension member 18D from the first sub-system and the tension member 18F 
from the second sub-system go to separate pulleys 64 and 64A, 
respectively, which are in the vertical plane through the two floats and 
are anchored to the sea floor. A cylinder 62 is anchored on the line 
joining the two pulleys 64 and 64A so that the piston rods 72 and 72A 
which extend out of the two ends of the piston 70 will be coaxial with the 
tension members between the pulleys. Conventional valving will be, of 
course, used. There will be, though not shown, the conventional stuffing 
glands at each end of the cylinder so that the piston rods can slidably 
seal the internal volume of the cylinder. 
Consider that the wave is moving to the right in FIG. 5. The first float 60 
will move upwardly with time and, of course, the float 60A which is now at 
the peak will move downwardly, and will soon be in a trough while 60 will 
be on a peak. The tension system then will thus move the piston from the 
left end of the cylinder to the right end of the cylinder. When the wave 
moves another half wave length, the reverse will happen and the piston 
will move back to the left side again. Thus, a double acting system is 
provided by use of the two floats in proper positioning on the line 
perpendicular to the wave front. 
FIG. 6 represents another embodiment in which a pump is powered by means of 
a float system 60B having the improvement of the energy storage compliance 
34F, and a tension member 18F, and an anchor point 36 on the sea floor 38. 
In this case the pump could be a tubing pump in a water or oil well, which 
are operated by conventional sucker rods 82. The sucker rods are tied 
directly to the float 60B. Pump outlet would be at 84. 
FIG. 7 represents schematically a different embodiment, in which the power 
extractive means is electrical, and the power generated is used to power a 
beacon light mounted on the float. The entire system is contained by the 
float 40, except for an anchor cable, or flexible tension member 18C and 
anchor system at point 36 on the sea floor 38. 
The system is indicated generally by the numeral 50 and comprises the float 
40 which floats on the surface 14 of the body of water 16. Again, the 
compliant member 34C is tied to the float at point 33C and to a tension 
means 18C at point 42. The flexible tension means 18C drives a pulley 44, 
on the shaft of the generator 58, which is supported by the float inside 
of the float. The generator leads 46 would go through a rectifier 44A to a 
battery 48 which would store the varying output of the generator as the 
wave height changes. Appropriate leads 56 would go from the battery to the 
beacon light 52 which would be mounted on supports 54 to the top of the 
float. 
FIG. 8 presents an example embodiment of a wave energy extraction or 
pumping apparatus, based on FIG. 1, generally designated by the reference 
number 100. The apparatus 100 is generally comprised of a float means 102, 
an anchor means 104, and an energy extraction means, generally designated 
106, connected between the float means 102 and the anchor means 104. In 
this embodiment, the energy extraction means 106 is a pump means which is 
comprised of a cylinder 108. The cylinder 108 is normally retained in a 
generally vertical position by the float means 102 and the anchor means 
104, and, in the example embodiment has a top end, generally designated 
110, and a bottom end, generally designated 112. For efficient operation, 
the bottom end 112 of the cylinder 108 should be closed and the top end 
110 of the cylinder should be vented, such as to atmosphere or to the body 
of water 134. If the top end 110 is to be vented to the body of water 134, 
the top end may simply be left open. 
The pump means 106 further comprises a reciprocal piston 114 in the 
cylinder 108 and a piston rod 116 which has a first end, generally 
designated 118, connected to the piston 114 and a second end, generally 
designated 120, which extends sealably out of the bottom end 112 of the 
cylinder 108. The piston rod 116 may be slidably sealed with the bottom 
end 112 of the cylinder 108 by a conventional packing box or stuffing 
gland. The second end 120 of the piston rod 116 is connected to the anchor 
means 104. The anchor means 104 limits the upward movement of the piston 
114 and piston rod 116 relative to the cylinder 108 and float means 102. 
The cylinder 108, in the example embodiment of FIG. 8, further comprises an 
inlet 122 and outlet 124 to the cylinder with an inlet check valve 126 
connected to the inlet 122 and an outlet check valve 128 connected to the 
outlet 124. The inlet check valve 126 allows water to flow into, but not 
out of the cylinder 108 through inlet 122. The outlet check valve 128 
allows water to flow out of, but not into, the cylinder 108 through outlet 
124. 
The pump means 106 is further comprised of a mechanical tensioning means 
130, mechanically connected between the piston 114 and the cylinder 108, 
for maintaining resilent tension between the piston 114 and the cylinder 
108 and for downstroking the cylinder 108 relative to the piston in 
response to a falling wave action. The mechanical tensioning means 130 may 
be connected between any points on the cylinder 108 or apparatus 100 and 
piston 114 which will not interfere with the reciprocal travel of the 
piston 114 and which will allow the mechanical tensioning means 130 to 
maintain resilient tension between the piston 114 and cylinder 108, which 
will also maintain the cylinder 108 and float means 102 under downward 
tension. The mechanical tensioning means should be sized to maintain 
sufficient tension between the piston 114 and cylinder 108 that the float 
102 will be held in tension with the surface of the water at all 
anticipated water, wave, or tide levels. The selected tension should 
maintain the apparatus 100 in a generally vertical orientation and allow 
the piston 114 to substantially stroke inside the cylinder 108 as the 
float 102 and cylinder 108 rise and fall with each wave at all anticipated 
water or tide levels. 
The float means 102 is connected to the cylinder 108 and captures the wave 
energy necessary to reciprocate the cylinder 108 relative to the anchored 
piston 114 as the float means rides up and down on passing waves 132 in 
the body of water 134. Preferably the float means 102 is connected near 
the top end 110 of the cylinder 108. In the example embodiment of FIG. 8 
the float means 102 is connected to the cylinder 108 with a flexible 
tensile means 136, such as a cable or chain. The anchor means 104 should 
also be flexibly connected to the piston rod 116 with a flexible tensile 
means 138, such as a cable or chain. 
In operation, as the float means 102 floats up on a passing wave the 
cylinder 108 is pulled upwards relative to the anchored piston 114 and 
piston rod 118. In the embodiment of FIG. 8, the inlet 126 and outlet 128 
are located on the cylinder 108 between the bottom end 112 of the cylinder 
and the lowermost position of reciprocal travel of the piston 114 relative 
to the cylinder 108, as illustrated in FIG. 8. Therefore, as the float 
means 102 and cylinder 108 rise on the wave 132, the relative downward 
motion of the anchored piston 114 forces water out of cylinder 108 through 
the outlet check valve 128 and imparts energy to mechanical tensioning 
means 130. As the float means 102 and cylinder 108 fall with a wave 132 
the mechanical tensioning means 130 pulls the cylinder 108 downward and 
the relative upward motion of the piston 114 into the cylinder pulls water 
into the cylinder through the inlet check valve 126. 
As illustrated in the example embodiment of FIG. 8 the mechanical 
tensioning means 130 may comprise a spring, also designated 130, connected 
between the piston 114 and cylinder 108. The spring may be connected in 
any manner which will maintain resilient tension between the piston and 
cylinder. As exemplified in FIG. 8, the spring 130 can be connected inside 
the cylinder 108, between the piston 114 and the top end 110 of the 
cylinder. In the configuration of inlet 126 and outlet 128, illustrated in 
FIG. 8, the piston 114 may be selected to sealingly isolate the spring 130 
from contact with the pumped water and the top end 110 of the cylinder 108 
may be sealed to enclose the spring 130 in a substantially watertight 
spring compartment 140. This isolation from water contact may be desired 
to prolong the life of the spring 130. If the spring 130 is so isolated, 
the efficiency of the apparatus 100 should be enhanced by venting the 
spring compartment 140 to the surface, by enlarging the cylinder 108 and 
spring compartment 140, or by taking other measures to decrease the 
resistance of the closed spring compartment 140 to compression. If it is 
not desired to isolate the spring 130 from water contact, the top end 110 
of the cylinder 108 may be left open to increase the efficiency of the 
apparatus 100. The spring 130 may also be located outside the cylinder 
108. For example, the spring 130 may be connected between the second end 
120 of piston rod 116 and the outside surface of cylinder 108. 
The wave energy extraction system 100 may also comprise a conduit 142 
connected from the outlet check valve 128 and extendable to an area where 
the pumped water may be useful. 
The mechanical tensioning means 130, exemplified as a spring in FIG. 8, may 
also comprise a weight 143 and tether 144, as exemplified in FIG. 11. The 
tether 144 extends from a fast connection 145 with piston 114 through a 
slidable connection 146 with cylinder 108 to a fast connection 147 with 
the weight 143. The slidable connection 146 is a pulley, also designated 
146, in the preferred embodiment although any type of connection which 
will slidably engage the tether 144 with the cylinder 108 will work. The 
weight 143 and tether 144 may be connected in any manner, through any 
number of pulleys, which will maintain resilient tension between the 
piston 114 and cylinder 108. For example, the tether 144 could be 
connected from the second end 120 of piston rod 116 through a pulley 
mounted on the outside of cylinder 108 to a weight. The use of the weight 
143 and tether 144 should be particularly beneficial when the float means 
102 has buoyancy greater than the resilient strength of available springs. 
The size and mass of the weight 143 may be varied as necessary to maintain 
resilient tension between the float means 102 and the pump means 106. 
FIG. 9 presents an example embodiment of a wave energy extraction or 
pumping apparatus, based on FIG. 2, generally designated by the reference 
number 150. The apparatus 150 is generally comprised of a float means 152, 
an anchor means 154, and an energy extraction means, generally designated 
156, connected between the float means 152 and the anchor means 154. In 
this embodiment the energy extraction means 156 is a pump means which is 
comprised of a cylinder 158. The cylinder 158 is normally retained in a 
generally vertical position by the float means 152 and the anchor means 
154 and, in the example embodiment, has a top end, generally designated 
160, and a bottom end, generally designated 162. For best operation, the 
top end 112 of the cylinder 160 should be closed and the bottom end 162 of 
the cylinder should be vented, preferably to atmosphere or to the body of 
water 134. If the top end 110 is to be vented to the body of water 134, 
the top end may simply be left open. 
The pump means 156 further comprises a reciprocal piston 164 in the 
cylinder 158 and a piston rod 166 which has a second end, generally 
designated 170, connected to the piston 164 and a first end, generally 
designated 168, which extends sealably out of the top end 160 of the 
cylinder 158. The piston rod 166 may be slidably sealed with the top end 
160 of the cylinder 158 by a conventional packing box or stuffing gland. 
The first end 168 of the piston rod 166 is connected to the float means 
152. 
In this embodiment, the anchor means 154 is connected to the cylinder 108 
and limits the upward movement of the cylinder relative to the piston 164 
and float means 152. Preferably, the anchor means 154 is connected to the 
cylinder 108 near the bottom end 162 of the cylinder. 
The cylinder 158, in the example embodiment of FIG. 9, further comprises an 
inlet 172 and outlet 174 to the cylinder with an inlet check valve 176 
connected to the inlet 172 and an outlet check valve 178 connected to the 
outlet 174. The inlet check valve 176 allows water to flow into, but not 
out of, the cylinder 158 through inlet 172. The outlet check valve 178 
allows water to flow out of, but not into, the cylinder 158 through outlet 
174. 
The pump means 156 is further comprised of a mechanical tensioning means 
180, mechanically connected between the piston 164 and the cylinder 158, 
for maintaining resilient tension between the piston 164 and the cylinder 
158 and for downstroking the piston 164 relative to the cylinder in 
response to a falling wave action, as illustrated in FIG. 9. The 
mechanical tensioning means 180 may be connected between any points on the 
cylinder 158 or apparatus 150 and the piston 164 which will not interfere 
with the reciprocal travel of the piston 164 and which will allow the 
mechanical tensioning means 180 to maintain resilient tension between the 
cylinder 158 and the piston 164, which will also maintain the piston 164 
and float means 152 under downward tension. The mechanical tensioning 
means 180 should be sized to maintain sufficient tension between the 
piston 164 and cylinder 158 that the float 152 will be held in tension 
with the surface of the water at all anticipated water, wave, or tide 
levels. The selected tension should maintain the apparatus 150 in a 
generally vertical orientation and allow the piston 164 to substantially 
stroke inside the cylinder 158 as the float 152 and piston 164 rise and 
fall with each wave at all anticipated water or tide levels. 
The float means 152 is connected to the piston rod 166 and captures the 
wave energy necessary to reciprocate the piston 164 relative to the 
anchored cylinder 158 as the float means 152 floats up and down on passing 
waves 182 in the body of water 184. In the example embodiment of FIG. 9 
the float means 152 is connected to the piston rod 166 with a flexible 
tensile means 186, such as a cable chain. The anchor means 154 should also 
be flexibly connected to the cylinder 108 with a flexible tensile means 
188, such as a cable or chain. 
In operation, as the float means 152 floats up on a passing wave 182, the 
piston rod 166 and piston 164 are pulled upwards relative to the anchored 
cylinder 158. In the embodiment of FIG. 9, the inlet 176 and outlet 178 
are located on the cylinder 158 between the top end 160 of the cylinder 
and the uppermost position of reciprocal travel of the piston 164 relative 
to the cylinder 158, as illustrated in FIG. 9. Therefore, as the float 
means 102 and piston 164 rise with a wave 182 the relative upward motion 
of the piston 164 into the cylinder 158 forces water from the cylinder 
through the outlet check valve 178 and imparts energy to the mechanical 
tensioning means 180. As the float means 102 falls with a wave 182, the 
mechanical tensioning means 180 pulls the piston 164 downward relative to 
the anchored cylinder 158 and pulls water into the cylinder 158 through 
the inlet check valve 176. 
As illustrated in the example embodiment of FIG. 9 the mechanical 
tensioning means 180 may comprise a spring, also designated 180, connected 
between the piston 164 and cylinder 158. The spring 180 may be connected 
in any manner which will maintain resilient tension between the piston 164 
and cylinder 158. As exemplified in FIG. 9 the spring 180 can be connected 
inside the cylinder 158, between the piston 164 and the bottom end 162 of 
the cylinder. In the configuration of inlet 126 and outlet 128 illustrated 
in FIG. 9, the piston 164 may be selected to sealingly isolate the spring 
180 from contact with the pumped water and the bottom end 162 of the 
cylinder 158 may be sealed to enclose the spring 180 in a substantially 
watertight spring compartment 190. This isolation from water contact may 
be desired to prolong the life of the spring 180. If the spring is so 
isolated, the efficiency of the system 150 should be enhanced by venting 
the spring compartment 190 to the surface, enlarging the cylinder 158 and 
spring compartment 190, or by taking other measures to decrease the 
resistance of the closed spring compartment 190 to compression. If it is 
not desired to isolate the spring 180 from water contact, the bottom end 
162 of the cylinder 158 may be left open to increase the efficiency of the 
apparatus 150. The spring 180 may also be located outside the cylinder 
158. For example, the spring 180 may be connected between the first end 
168 of piston rod 166 and the outside surface of cylinder 158. 
The pumping apparatus 150 may also comprise a conduit 192 connected from 
the outlet check valve 178 and extendable to an area where the pumped 
water may be useful. 
The mechanical tensioning means 180, exemplified as a spring in FIG. 9, may 
also comprise a weight 193 and tether 194, as exemplified in FIG. 12. The 
tether 194 extends from a fast connection 195 with cylinder 162 through a 
slidable connection 196 with piston 164 to a fast connection 197 with the 
weight 193. The slidable connection 196 is a pulley, also designated 196, 
in the preferred embodiment although any type of connection which will 
slidably engage the tether 194 with the piston 164 will work. The weight 
193 and tether 194 may be connected in any manner, through any number of 
pulleys, which will maintain resilient tension between the piston 164 and 
cylinder 158. For example, the tether 194 could be connected from the 
outside surface of cylinder 158 through a pulley mounted on the first end 
168 of piston rod 166 to a weight. The use of the weight 193 and tether 
194 should be particularly beneficial when the float means 152 has 
buoyancy greater than the resilient strength of available springs. The 
size and mass of the weight 193 may be varied as necessary to maintain 
resilient tension between the float means 152 and the pump means 156. 
In the following discussion concerning FIG. 10 apparatus 150 of FIG. 9 is 
specifically discussed for purposes of illustration, but it should be 
understood that the discussion is meant to apply to all water-pumping 
embodiments of this invention. 
FIG. 10 represents an exemplary use of the present invention as well as a 
means of protecting at least one embodiment of the apparatus 150 from 
excessive wave action. As illustrated in FIG. 10, at least one of the 
pumping apparatus 150 is connected to a water holding means 200. The water 
holding means 200 is located above the water level 202 of the body of 
water 204 and above the pumping apparatus 150. The water holding means 200 
may be a reservoir, surge pipe, or any means of at least temporarily 
retaining and directing the elevated pumped water and the potential energy 
stored therein. An example use of the elevated water, illustrated in FIG. 
10, would be to turn a turbine generator 208. 
The conduits 192 from the outlet check valves 178 are connected to the 
water holding means 200. In FIG. 10 conduits 192 are connected to the 
water holding means through common conduit 206. A valve means 210 is 
located in the conduit 206 above the water level 202 of the body of water 
204, and above the at least one pumping apparatus 150, for opening and 
closing the communication between the pumping apparatus and the water 
holding means 200 through the conduit 206. Conduits 192 may be 
individually connected to the water holding means 200 and may have a valve 
means 206 in each conduit 192. 
The valve means 210 may be used to protect a pumping apparatus 192 which 
has the inlet 172 and outlet 174 in the cylinder 158 located on the 
opposite side of the piston 164 from the mechanical tensioning means 180 
as illustrated in FIG. 9, (or FIGS. 8, 10, and 11) by closing the valve 
means 210. Closing the valve means 210 backs up water pressure against the 
outlet check valve 178 and the piston 164 of the pumping apparatus 150 and 
prevents the piston 164 and float means 152 from rising with the waves. 
With each successively lower wave trough the pumping apparatus 150 will 
draw more water into the cylinder 158, and since the piston 164 and float 
means 152 can not rise to discharge the water from the cylinder, the float 
means 152 will sink to the lowest wave trough level and remain there. The 
valve means 210 may be a manually or an automatically operated device. 
The described embodiments of the pumping apparatus may be made of low cost, 
easily obtained and replaced parts of plastic, polymer, metal, wood, and 
styrofoam. Because the parts are easily obtainable (metal, plastic or 
polymeric pumps, valves and floats are commercially available, as are 
springs, cables, chains, and anchors of various materials) they may be of 
cheaper materials having a limited life in order to keep the cost of the 
apparatus to a minimum. 
It will be clear that the presence of the mechanical storage means in each 
of these embodiments makes it possible for the float to rise as the wave 
surface rises as the ride rises. The force exerted on the float by the 
tension member through the mechanical storage means is sufficient to 
maintain the float on the surface of the water 14 and yet is compliant 
enough to permit the float to move upwardly as the tide's height 
increases. As the tide moves out and the level of the wave drops, then the 
mechanical storage means continues to provide the tension necessary to 
permit the float to move downwardly and also maintains sufficient tension 
between the piston and cylinder for the apparatus to function properly. 
While the invention has been described with a certain degree of 
particularity, it is manifest that many changes may be made in the details 
of construction and the arrangement of components. It is understood that 
the invention is not to be limited to the specific embodiments set forth 
herein by way of exemplifying the invention, but the invention is to be 
limited only by the scope of the attached claim or claims, including the 
full range of equivalency to which each element or step thereof is 
entitled.