U.S. patent number 3,890,661 [Application Number 05/444,406] was granted by the patent office on 1975-06-24 for surfboard rudder-fin combination.
Invention is credited to Robert F. Johnson.
United States Patent |
3,890,661 |
Johnson |
June 24, 1975 |
Surfboard rudder-fin combination
Abstract
A surfboard steered by a fin that functions as a rudder in
response to force due to gravity of surfer's body. A vertical shaft
connects the rudder-fin to the surfboard body. Its fixed space
relationship in respect to the rudder-fin divides the lateral
surface of the rudder-fin into two portions of unequal sizes. The
shaft is rotatably mounted in the body of the surfboard. A lever
arm adjustable in length is provided between the shaft and body to
vary steerability characteristics.
Inventors: |
Johnson; Robert F. (Calgary,
Alberta T2K 1R3, CA) |
Family
ID: |
23764743 |
Appl.
No.: |
05/444,406 |
Filed: |
February 21, 1974 |
Current U.S.
Class: |
441/79 |
Current CPC
Class: |
B63B
32/64 (20200201); B63B 32/60 (20200201) |
Current International
Class: |
B63B
35/73 (20060101); A63c 015/00 () |
Field of
Search: |
;9/31R,31A,31B,31E
;114/126 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Reger; Duane A.
Assistant Examiner: Sotelo; Jesus D.
Attorney, Agent or Firm: Sherrard; Tom
Claims
I claim:
1. In combination
a. a surfboard body portion,
b. a rudder mounted thereunder,
c. a vertical shaft, one end of which is rotatably mounted in the
body portion and the other end of which is integral with the rudder
in such space relationship that the two lateral rudder surface
portions on each side of the point of integration are unequal in
area dimensions,
d. a lever arm secured at right angles to and near the end of the
shaft which is rotatably mounted, and
e. resilient means movable in the fore and aft direction relative
to the vertical shaft for effectively changing the length of the
lever arm to vary the force required for rudder action.
Description
BACKGROUND OF THE INVENTION
With the rising popularity of surfing the manufacturers of
surfboards have provided refined and precision products to
accommodate the skills and talents that more and more surfers are
developing. Heretofore the fixed fin and lack of moving parts on
surfboards has limited opportunities of maneuverability of the
board. Some slight directional control of conventional boards is
achieved by only the most accomplished surfers but the usual boards
cannot be quickly and decisively manipulated for the maximum
potential inherent in each wave being ridden to the shore. Ability
to steer a board would add new dimensions to surfing in that
surfers would then be able to guide the board into, and remain
upon, the best part of each wave for optimum surfing. Before my
invention there has been no simple, practical means for steering a
surfboard.
SUMMARY OF INVENTION
In place and instead of the well known fin fixed to a board, I have
provided a fin that is slightly rotatable in respect to the body of
the board. It is mounted in such a manner that the surfer causes
the fin to change alignment with the board merely by changing his
position on the board. As a result, he is able to steer the board
through the water, on a controlled and desired course, simply by
shifting his feet (and thereby body weight) to various places on
the board.
BRIEF DESCRIPTION OF DRAWING
In the accompanying drawings
FIG. 1 is a perspective sectional view of a portion of my invention
showing the connection of the rudder-fin to the surfboard body.
FIG. 2 is a diagram from the end of the board illustrating the
resolution of forces which cause my invention to operate.
FIG. 3 is a top plan diagram taken along line 3 of FIG. 1 showing
the means for controlling the ease of turning.
DESCRIPTION OF PREFERRED EMBODIMENT
In the drawings forming a part hereof wherein like numerals
represent like parts throughout, reference numeral 1 is a body
portion of the typical surfboard. My novel components may either be
integrated therewith or may be a separate assembly which sets into
the body portion in the area where the fin usually attaches. Item 2
is a cap which may be used to retain the described parts. It is
essentially a retangular block journalled to retain rotatable shaft
3. The upper portion of shaft 3 may extend into the body as
illustrated. It is operatively mounted in the cap and body. An
important feature of my invention is the space relationship of the
fin and shaft affixed thereto. It is critical that the shaft is not
centrally located in the fin. As illustrated in FIG. 1, if the axis
of the shaft extended down through the fin it would necessarily
divide the fin into two unequal sections 7 and 7'. In this manner,
the weight of the surfer, represented by numeral 11, of FIG. 2, on
one edge of the board causes, as usual, the edge of surfboard 12 to
dip below waterline 13. Resultant natural lateral movement of board
in direction of arrow 14 causes resistance of the water, in
direction of arrows 15, due to inertia. The total resistance is
more on surface section 7 than section 7' because section 7 has
greater surface area than section 7'. Since the fin can rotate on
shaft 3, section 7 yields to the lateral force of the water and the
fin changes its alignment and thereby acts as a rudder. Of course,
a shift of the surfer's weight to the other side of the board would
cause a turning in the opposite direction because of a reversal of
all forces. Thus the surfer can steer the board simply by shifting
his weight on the board.
Those skilled in the art may devise means to adjust the amount of
turn for particular boards and particular surfers without departing
from the scope of my invention. For example, I have illustrated one
such means. In this assembly retention lever or arm 5 has one end
secured to the shaft and it is disposed at right angles thereto. An
open space 10 is provided in the body so the arm can freely move
when the shaft turns. A retainer 4 has arm 5 projecting through it.
The retainer 4 has dual spiral springs 6 and 6' abutting each side
of arm 5 to provide desired resistance. To adjust the ease at which
the arm, and therefore the fin, may be turned, I have provided dual
track 9 with dual securing screws or bolts 8 slideably mounted
therein. For great resistance the screws 8 are loosened and slid in
track 9 away from the shaft, and then tightened. The resulting long
lever arm 5 offers less resistance to turning than if retainer 4,
were placed close to the shaft.
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