U.S. patent application number 11/731701 was filed with the patent office on 2008-10-02 for articulated oar system.
Invention is credited to John C. Bowen.
Application Number | 20080242163 11/731701 |
Document ID | / |
Family ID | 39795237 |
Filed Date | 2008-10-02 |
United States Patent
Application |
20080242163 |
Kind Code |
A1 |
Bowen; John C. |
October 2, 2008 |
Articulated oar system
Abstract
An oar system is provided that keeps the blade of the oar at
approximately 90 degrees to the centerline or keel of a boat
throughout the normal power producing stroke. This reduces the lost
effort that is expended when operating oars whose blades are fixed
to the oar shaft. A series of cables and pivotal attachment points
holds the oar blade at the approximate 90-degree angle to the boat
keel.
Inventors: |
Bowen; John C.; (Huntingdon
Valley, PA) |
Correspondence
Address: |
Zachary T. Wobensmith, III
7746 101st Court
Vero Beach
FL
32967-2871
US
|
Family ID: |
39795237 |
Appl. No.: |
11/731701 |
Filed: |
April 2, 2007 |
Current U.S.
Class: |
440/101 |
Current CPC
Class: |
B63H 16/04 20130101 |
Class at
Publication: |
440/101 |
International
Class: |
B63H 16/04 20060101
B63H016/04 |
Claims
1. An articulated oar system for propelling a boat which comprises
an oar shaft, a blade connected to the oar shaft, means connecting
said oar blade to said oar shaft whereby said blade is kept at an
angle approximately 90 degrees to the keel of the boat during the
power stroke of said system.
2. An articulated oar system as defined in claim 1 in which said
blade can pivot with the water current at the end of a rowing
stroke to prevent injury to the rower.
3. An articulated oar system as claimed in claim 1 in which said
oar blade is always kept at an approximate angle of 90 degrees with
the keel of the boat so that back pressure may be exerted on the
oar to control the motion of the boat.
4. An articulated oar system as defined in claim 1 in which said
connecting means includes at least one rod or cable to hold said
blade in position.
5. An articulated oar system as defined in claim 1 in which said
connecting means includes a thrust rod to hold the blade in
position during its use, wherein the blade is free to rotate or
pivot in accordance with the flow of the water.
6. An articulated oar system as defined in claim 1 or 3 in which
said oar blade can be rotated horizontally by 90 degrees during its
return stroke to keep the blade parallel to the water.
7. An articulated oar system as defined in claim 1 in which said
connecting means has at least one spring means to provide tension
to the cable or rod during some portion of the rowing stroke.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention pertains to an articulated oar system of the
type which holds the oar blade at the optimum angle to produce the
most efficient power stroke.
[0003] 2. Description of the Prior Art
[0004] There have been many attempts over the past several thousand
years to maximize the efficiency of moving a boat over the water.
The Triremes of ancient times obtained very good speeds by using a
short oar stroke, three rows of rowers atop one another and then
with the help of sails, they obtained the speed necessary to ram
another boat and crack its hull. This speed has been calculated to
be 10 knots.
[0005] In more modern times, there have been several patents issued
that claimed to improve the efficiency of rowing. U.S. Pat. No.
4,383,830 used a variable oarlock position to keep the oar blade in
nearly perpendicular position to the keel of the boat. The cost of
the installation proved too expensive and was banned from
competition. U.S. Pat. No. 4,383,830 shows an arrangement for using
the feet to adjust the position of the oar lock to improve
efficiency by keeping the oar blade more perpendicular to the keel
of the boat. U.S. Pat. No. 3,677,216 shows a spring-loaded blade,
which can be dragged through the water on the return stroke without
removing it from the water.
[0006] In neither case is there a suggestion that the oar blade
should be kept at right angles to the keel. EP 1 391 379 A1 shows a
means of rowing a boat in the direction of the rowers' view and
allows the oars to be nearly perpendicular to the hull, but that
does not seem to be the primary purpose of the arrangement and it
requires special sliding oarlock arrangements.
[0007] Many oars and oarlock arrangements have been proposed for
boats over the years. None have described an arrangement similar to
that herein described. In racing shells in particular, it is
important to conserve the energy used in moving the boat through
the water. Each rower has a finite amount of energy that he or she
may expend in a given period of time.
[0008] It is therefore important that the effort put forth is used
in the most efficient manner. Rowers are generally able to put
forth the maximum effort during the time period when the oar is
between -55 degrees and -35 degrees from a perpendicular to the
keel extending through the oarlock.
[0009] The arrangement herein described allows the oar blade to
slip more easily through the water during this time period. The
reason that this is accomplished is that the oar blade is held
perpendicular to the keel of the boat and in moving away from and
along the boat, the majority of water that is displaced by the oar
blade is along the line of the keel of the boat and a minimum is
displaced away from the boat. With a standard oar, the water that
is displaced during this -55 to -35 degree angular sweep of the oar
is away from the boat and only a fraction of the energy is
converted into propelling the boat.
[0010] A further object of this invention is to allow the rower to
easily remove the oar from the water at the end of a stroke because
he/she has the oar blade too deep in the water. This is
accomplished by having the oar blade attached in such a manner that
it can easily swing towards a parallel position with the current
and thus is more easily extracted from the water.
DESCRIPTION OF THE DRAWINGS
[0011] The nature and characteristics of the invention will be more
easily understood from the following description taken in
connection with the accompanying drawings forming a part hereof in
which:
[0012] FIG. 1 is a front elevation view of the articulated oar
system of the invention showing the position of the oar and the
control arms and/or cables during the return stroke.
[0013] FIG. 2 shows the plan view of the oar and other parts.
[0014] FIG. 3 shows the blade portion of the oar assembly and the
return spring.
[0015] FIG. 4 is a view similar to FIG. 3 except with a 90-degree
rotation.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0016] When referring to the preferred embodiment, certain
terminology will be utilized for the sake of clarity. Use of such
terminology is intended to encompass not only the described
embodiment, but also technical equivalents, which operate and
function in substantially the same way to bring about the same
result.
[0017] Referring now to FIGS. 1-4 and more particularly to FIG. 2,
it shows the oar system arrangement in plan view on a boat with the
oar shaft 1 pivoting about a point 7 in the center of the oar shaft
1 and using an oarlock. This is the type of oarlock that allows the
oar shaft 1 to rotate in a manner so that the center of the oar
shaft 1 is over the point of rotation. On a parallel line with the
center line of the hull of the boat 20 is an attachment point 10
for a cable or solid rod 2 to be attached, allowing the cable or
rod 2 to rotate about the point 10 and which is also lifted with
the oar shaft 1. Such attachments are commercially available. The
other end of this cable or solid rod 2 is pivotally attached at a
point 8 to rods(s) 3 that can also be pivotally attached to the end
of the oar shaft 1, that is furthest away from the centerline of
the boat 20. Also attached at this point 8 is either a string or
cable 5 that is attached to the outer end of an oar blade 4. (There
could also be multiple strings or cables for 2 and/or 5.) The inner
end of the oar blade 4 is pivotally attached to the end of the oar
shaft 1. As an alternate arrangement, the rod 3 can be rigidly
attached to the oar blade 4 eliminating the need for the cable(s)
5. A spring 12 supplies a force to the blade 4 so as to keep the
cable 5 taught at the end of the return stroke. The action of
spring 12 can be adjusted by the way that it is manufactured to
supply force during all of the stroke or just at the end of the
return stroke.
[0018] One arrangement allows the cables or rods 2 to be in tension
during the entire power portion of the stroke. At the end of this
stroke, the oar shaft 1 and blade 4 are as shown in the FIG. 2. At
this point the oar is normally lifted from the water to return to
the starting point 11. The dashed lines indicate the relative
position of the oar shaft 1 and blade 4 and the cable 5 at 0
degrees and -55 degrees from a perpendicular to the keel (not
shown) of the boat 20. Should the rower fail to promptly lift the
oar shaft 1 from the water at the end of the stroke, the blade 4
will pivot about the point 6 and therefore prevent the rower from
being struck by the handle end of the oar shaft 1 as would occur
with a fixed blade submerged in the moving water. This most often
happens when the rower has set his oar blade too deeply in the
water.
[0019] By use of the above-described system, the blade 4 is
properly kept at approximately 90 degrees to the centerline of the
keel of the boat 20 during the power-producing phase of the stroke
producing maximum efficiency. Instead of the blade 4 pushing water
away from the boat 20 at the beginning of the stroke, it slides
away from the boat 20 with little resistance and all of the power
that the rower is able to put to the oar shaft 1 results in thrust
to the oarlock and the boat 20. This action is determined by the
relative distances of the pivot point 10 to the pivot point 7 and
the pivot point 8 to the pivot point 6. These distances normally
would be equal, but there may be advantages to making them slightly
unequal so that instead of a perfect parallelogram, the blade 4 is
more open or closed at the beginning and end of the stroke. This
will result in a different action, which will either push the oar
shaft 1 toward the oarlock or pull it out away from the oarlock.
This will affect the feel of the oar in the hands of the rower.
Changing the length of rod or cable 2 relative to the length of the
oar shaft 1, past the oarlock, results in a similar action.
[0020] If the oarlock is of the type most commonly used today, that
is an oar shaft that rotates about a fixed post, the same desired
action can be obtained by finding that point in space that allows
the cable or other system mentioned above the control the position
of the oar blade 4 in the manner desired. The attachment point for
the cable or rod 2 nearest to the blade 4 can be definitively
located. The points in space for the point 8 when the blade is
perpendicular to the keel can be calculated using simple
trigonometry and the appropriate attachment point for the cable or
rod 2 near the oar lock can be determined using well known
appropriate formulae.
[0021] FIG. 2 shows a plan view of the arrangement, wherein 1 is
the oar shaft, 2 is the parallel cable or rod, 3 is a spacer piece
to which the cable or rod is attached, 4 is the blade of the oar, 5
is another rod or cable that attaches the blade to a spacer piece
3, 6 is a hinge or flexible joint, 7 is the position of the oar
lock or pivot pin, 8 is the attachment point of the cables or rods
5 that connect the blade 4 to the outrigger for the oar lock, 9 is
the tip of the blade and 11 is the position of the flexible joint
or hinge at the most rearward position of the oars motion.
(Approximately -55 degrees from a vertical to the keel.)
[0022] FIGS. 3 and 4 show the essential parts of the oar assembly.
The spacer piece 3 is shown attached to the oar blade, but it also
may be attached to pin 6 of the hinge by means of a fork
arrangement. The length of the part 3 is a compromise between the
various stresses and ease of operation. The shorter part 3 is, the
higher the stresses in the cable and part 3, the longer that it is,
the lower the stresses, but then the assembly becomes more
difficult to handle.
[0023] It is easily imagined that bar 3 if attached to the blade 4
could be extended on the other wide of the blade 4 and another
cable attached to it. In such an arrangement the oar blade 4 is
always perpendicular to the keel of the boat, but now can be used
to propel and to reverse the direction of the boat. This is
especially important when the boat is used for pleasure and
backpressure on the blade 4 is important to maneuver the boat.
[0024] Another arrangement would be to have a rod in compression
(not shown) held along the oar shaft in such a manner as to resist
the movement of the blade and yet release it at the end of the
stroke.
[0025] It will thus be seen that structure has been provided with
which the objects of the invention are achieved.
* * * * *