Marine propulsion – Operator powered drive for propelling means – Rocking watercraft
Patent
1995-11-17
1998-10-06
Swinehart, Ed L.
Marine propulsion
Operator powered drive for propelling means
Rocking watercraft
440 14, B63H 1600
Patent
active
058168710
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a muscle-powered watercraft comprising flotation means and propulsion means having at least two blades. These blades may be made of a single part or in certain cases of two parts joined rigidly together by a common axle so that they can be considered as constituting a single blade having two parts.
Many watercraft of this type are known, at least from the literature. However none of them can be considered as a commercial success because the energy efficiency is low and the movement to be performed makes hard work, so the public instead prefers more conventional watercraft such as rowing boats or pedalos.
The research leading to the present invention has been directed to three points: firstly a play-like, sporting, balancing movement which can develop a feeling for water; secondly a substantial improvement of the energy efficiency; and lastly an original mode of operation which consists in causing the watercraft to plunge in and then out of the water with a constantly-propulsive sinusoidal trajectory.
To this end, the invention concerns a muscle-powered watercraft comprising flotation and propulsion means having at least two blades which remain rigid under the stresses they are subjected to, characterized in that the front edges of the blades are hinged about respective axes transverse to the watercraft's axis of propulsion, spaced from one another along said axis of propulsion on either side of the watercraft's center of gravity, each of these blades extending symmetrically from said axis of propulsion, there being abutment means for limiting the angle of freedom of each blade about its hinging axis, and the volume of water displaceable by immersion of said flotation means being selected to correspond to 1 to 2 times, preferably 1.2 to 1.5 times, the total laden weight of the watercraft, said flotation means having feet-supporting surfaces arranged about the craft's center of gravity, whereby a driver may impart to the watercraft a sinusoidal movement in and out of the water by pitching the craft and hence make the blades operate in opposition to one another between said abutments.
The advantage of this watercraft comes from two elements which in combination enable a substantial improvement of the propulsion energy. One of these elements is the use of rigid blades freely hinged between two abutments, which is a simple and efficient system. The other is the use of flotation means which, in response to a pitching movement communicated to the watercraft, allow the watercraft to adopt a sinusoidal movement in and out of the water. Due to this movement, the two blades situated on either side of the watercraft's center of gravity operate in phase opposition but produce forces directed alternately upwards or downwards and each having a component in the direction of propulsion. The sine may have a substantial amplitude so that the idle movements during which the phase inversion of these blades tipping from one abutment to the other represents only a small proportion of the total propulsive movement. In any event, this tipping phase of the blades does not constitute a loss of efficiency because at that moment the downwardly- or upwardly-acting vertical force is in a no-load situation; only a small fraction of the force is needed to produce the tipping itself. As there is no resistance, the speed of the movement increases and when it reaches the abutment at greater speed, the force is restituted. Moreover, each user may adjust the degree of flotability of his watercraft as a function of his own weight and muscular force, which enables the production of sinusoidal movements in and out of the water of greater or smaller amplitude.
BRIEF DESCRIPTION OF THE DRAWINGS
The accompanying drawings show, schematically and by way of example, three embodiments of the watercraft according to the invention.
FIG. 1 is a plan view of a first embodiment.
FIG. 2 is a view in longitudinal cross-section along line AA' of FIG. 1.
FIG. 3 is an elevational view of
REFERENCES:
patent: 2195527 (1940-04-01), Whiting
patent: 3384910 (1968-05-01), Heston, Jr. et al.
patent: 3557735 (1971-01-01), Dreyfus
patent: 3718109 (1973-02-01), Skitsko
patent: 3833956 (1974-09-01), Meehan
patent: 4371347 (1983-02-01), Jakobsen
"Catamaran Wiggles Through the Water Like a Fish", Popular Mechanics, No. 122, Sep. 1964 p. 97.
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