US20160325813A1

US20160325813A1 - Cycling Hull with Slow-Relative-Motion Hydrodynamics

Info

Publication number: US20160325813A1
Application number: US14/708,190
Authority: US
Inventors: Tracy Don Witham
Original assignee: Individual
Current assignee: Individual
Priority date: 2015-05-09
Filing date: 2015-05-09
Publication date: 2016-11-10

Abstract

Device (1) creates slow-relative-motion hydrodynamics in a cycling hull (10) when multiplicity of hull sections (11) moves between multiplicity of rotatable end waterline turnabouts (20) and multiplicity of rotatable keel turnabouts (30). When device (1) moves across water, multiplicity of hull sections (11) cycles via connection to pivotable connection (12), which pivots about multiplicity of rotatable end waterline turnabouts (20) and multiplicity of rotatable keel turnabouts (30). This puts cycling hull (10) in motion. Since the bottom of multiplicity of rotatable keel turnabouts (30) is lower than the bottom of multiplicity of rotatable end waterline turnabouts (20), the portion of cycling hull (10) moving between multiplicity of rotatable end waterline turnabouts (20) and multiplicity of rotatable keel turnabouts (30) also travels the full draft of device (1). As there is no relative motion between the water and multiplicity of hull sections (11) as it cycles along the keel line set up between first keel turnabout with axle (31) and second keel turnabout with axle (32), so there is slow relative motion between the water and multiplicity of hull sections (11) as they cycle between multiplicity of rotatable end waterline turnabouts (20) and multiplicity of rotatable keel turnabouts (30). The slow relative motion can be quantified as the product of dividing the vertical distance between the waterline and the keel line by the horizontal distance between rotatable end waterline turnabouts (20) and rotatable keel turnabouts (30), which produces a percentage of the overall speed of device 1 as it moves across water.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

Not Applicable

FEDERALLY SPONSORED RESEARCH

Not Applicable

SEQUENCE LISTING OR PROGRAM

Not Applicable

BACKGROUND

1. Field
This invention pertains to boat hull design by facilitating a slow-relative-motion area between end turnabouts and keel turnabouts in a cycling hull.
2. Prior Art
The idea of eliminating relative motion at the water interface between the turnabouts of a cycling hull has been recognized as possible since George H. Young's patent for an “Improved Marine Car,” U.S. Pat. No. 000,056,660, was issued on Jul. 24, 1866. While the aim of Young's invention was to reduce skin friction by eliminating relative motion, “residual resistance” (wave and turbulent resistance considered together) is typically a bigger source of watercraft resistance than is water friction, since residual resistance increases exponentially with increases in watercraft speed. Thus, the churning of the water at the end turnabouts of a cycling hull, where the hull sections are planted and pulled, presents a crucial challenge.
The strategy described herein to slow relative motion as cycling hull sections are planted and pulled next to the end turnabouts is found in no prior art. As a result, the potential of a cycling hull to create unprecedented efficiencies for marine transportation has gone unsuspected and unrealized.
An understanding of the objects and advantages of a cycling hull with slow-relative-motion hydrodynamics begins with an understanding of the idea that inspired the best prior art: wheeled efficiency is relevant to watercraft.
As the contact point of a rolling wheel is motionless relative to the surface over which it moves, so the point of frictionless contact between a rolling wheel and its point on a solid can be extended indefinitely by aligning a pair of wheels in a plane and using them as turnarounds for a continuous cycling track, as is commonly done with “caterpillar track.” There are two ways to apply this extended no-relative-motion contact area between the turnabouts of a cycling track to watercraft. Accordingly, there are two main branches in the prior art: (1) the cycling hull, in which the track itself is made buoyant, and (2) a strategy to cycle the track around (or sometimes partially within) another source of buoyancy. In both cases a water conveyance is created in which the percentage of the vessel that is in relative motion against the water can be reduced indefinitely by extending the track. So, in both cases, the reason for the wheel's extraordinary efficiency as a land conveyance is applied to water conveyance to affect a near total reduction in water friction.
That said, the prior art affects an ironic squandering of efficiency through poor design choices. The squandering begins with Young who called the cycling hull that conveys his 1866 “Marine Car” a “Chain Propeller” in the drawing sheets, a designation which suggests a fundamental misunderstanding of the true novelty of his invention: Whereas a watercraft propeller must engage water effectively, a water conveyance achieves efficiency by reducing that engagement. In fact, Young's perspective was confused with respect to his invention's main objective, and an ironic approach to achieving marine efficiency using cycling hulls that is endemic in the relevant art begins with Young.
Several design ironies with respect to efficiency are universal in the first or “cycling hull” branch of the prior art, but a transverse contouring of the hull sections is especially damaging. A transverse orientation sets up multiple instances of bluff form aerodynamic resistance as the cycling hull cycles. But if care is not taken to “streamline” the overall contour of the hull sections, increasing air resistance may outstrip the decrease in water skin friction. No care to streamline the overall contour is taken in any of the cycling hull branch of the prior art. That's curious, as the tradeoff for eliminating relative motion between the turnarounds is a doubling of air speed between the turnarounds when the hull sections are out of the water. Now if the primary goal were to engage the water for propulsion, perhaps the unfortunate tradeoff from an efficiency standpoint would be worthwhile. But since the primary goal is more efficient conveyance through water, a design uninformed by the need to minimize aerodynamic drag is clearly counterproductive.
Because it ought to be obvious to anyone competent in the relevant arts that aerodynamic efficiency should not be ignored with a cycling hull boat, the obvious advancement over the prior art attained by streamlining the overall contour of the cycling hull sections is not claimed herein. Nevertheless, is it important to note that 149 years of prior art that is ironic with respect to efficiency provides no relevant commentary on the potential of a cycling hull to improve the efficiency of marine conveyance; and that, therefore, for all practical purposes, the art described herein constitutes the beginning of a productive approach to the design of an efficient cycling hull.
Specific examples of cycling hulls in the prior art begin, again, with U.S. Pat. No. 000,056,660 to Young (1866), and include U.S. Pat. No. 424,076 to Pond (1890), U.S. Pat. No. 317,0533 to Fewel (1965), U.S. Pat. No. 4,715,668 to Burmeister (1987), and U.S. Pat. No. 6,582,258 to Morin (2003). Tellingly, only the earliest patents (to Young in 1866 and Pond in 1897) have increased efficiency as an object. In the abstract it is surprising that no prior art, from this line of development, makes a sophisticated attempt to realize the theoretical advantage that cycling hulls have from an efficiency standpoint. In historical context it is clear that the rise of the internal combustion engine in the 20^thCentury eclipsed market incentives to create disruptive technological efficiencies in the transportation industry.
A second universal flaw in the prior art, however, provides a more telling reason for the primitive state of the prior art: The prior art does not address the main class of resistance to a vessel's movement through water (residual resistance). Thus, sophisticated designers can be presumed to have surmised that cycling hulls are not worth the trouble. We will return to this point after considering the other main line of development originating with Young. But since the entire first branch prior art is ironic with respect to efficiency, it is pointless to consider it further.
The other main branch of development subsequent to Young uses a displacement hull in conjunction with a track which cycles either partially inside the hull/hulls or around it/them. In these designs the track is either not buoyant or does not provide full buoyancy to the vessel—as the hull or hulls provide some or all of the buoyancy. In one sense the prior art that expounds this second course of development is not relevant to the present invention (a cycling hull), since the primary source of buoyancy does not cycle. But as a line of development which attempts to reduce resistance to the progress of a hull through water by using a cycling track it does represent a descendent of the insight that inspired Young's 1866 innovation. (As used herein, unlike a “cycling hull,” a “cycling track” does not provide full design displacement by itself.)
Again, the effect of eliminating relative motion between the hull surface and the water is to eliminate just “skin friction.” The hulls sections must still push water aside in the manner of a traditional watercraft, thereby creating waves. And as the speed of the hull/water interface rises, movement at the boundary layer of water (where skin friction occurs) gains kinetic energy, which spreads out from the boundary layer, creating turbulence. And again, since wave and turbulent resistance are usually classed together as residual resistance, since both rise exponentially with the speed of the hull/water interface, residual resistance is typically the biggest source of resistance to the motion of a hull through water. So, if increasing watercraft efficiency is the goal, an approach which neglects residual resistance constitutes a mostly ineffective strategy.
The entire second course of development since Young neglects residual resistance. Examples include U.S. Pat. No. 532,220 to Thomas (1895), U.S. Pat. No. 1,913,605 to Martin (1933), U.S. Pat. No. 2,091,958 to Braga (1937), U.S. Pat. No. 2,279,827 to Lapidovsky (1942), U.S. Pat. No. 2,377,143 to Golden (1945), U.S. Pat. No. 3,205,852 to Shepard (1965), U.S. Pat. No. 3,621,803 to Foster (1971), U.S. Pat. No. 3,976,025 to Russell (1976), U.S. Pat. No. 4433634 to Coast (1984), U.S. Pat. No. 4,846,091 to Ives (1989), U.S. Pat. No. 5,845,593 to Birkestrand (1998), U.S. Pat. No. 5,845,595 to Atkinson (1998), and U.S. Pat. No. 6,482,053 to Prestenbach (2002). So there is no example of a mostly effective strategy to address hydrodynamic resistance, as both branches of innovation fail to address residual resistance.
A single apparent exception to the wholesale dismissal of the prior for having no strategy to address residual resistance occurs in U.S. Pat. No. 6,508,188 to Jim Dong (Jan. 21, 2003), where Dong expresses the misunderstanding first evidenced in Young (with his designation of his invention as a “chain propeller” in his drawing sheets) as follows: “the use of the belt [or track] for propulsion purposes is entirely contrary to the intended purpose of lessening the friction between the hull of a vessel and the body of water through which it is passing.”
But Dong's underlying rationale is flawed, which made it seem that his creation of a very sophisticated innovation to reduce residual resistance was needed. First, he uses the underlying design priority—clearly and truly expressed—to misunderstand a dual reality crucial to grasping the design challenge at hand. The dual underlying reality is that boats need propulsion and that the most efficient propulsion occurs when the interface between the water and the propulsion is as large as possible (less turbulence is created for any given power input when that input is spread over a larger interface). But the largest possible interface between a watercraft and the water through which it moves is the full displacement affected by the watercraft. So, yes, Dong's point is well taken that it is the “lessening of the friction between the hull of a vessel and the water through which it is passing” which expresses the primary goal; but that does not eliminate the fact that the vessel's full displacement presents the best possible opportunity to create efficient propulsion, and that the full displacement should often be used for propulsion in conjunction with a cycling hull or track, as a cycling hull uniquely makes that possible. (Exceptions would only occur where (1) it is desirable to tow a cycling hull, or (2) when the motive force of hydrodynamic resistance putting the cycling hull in motion will be smaller than the resulting aerodynamic resistance. The second case can arise when the cycling hull designer targets the sweet spot between 4 knots where water resistance typically spikes and 14 knots where air resistance does so.) In short, not only are propulsion and conveyance not intrinsically at odds, often a convergence of the two will be desirable for achieving maximum efficiency in a marine vessel.
And second, Dong invented a complex solution—submarine hulls enveloped with cycling exteriors set on struts to support the topside of a watercraft—to address residual resistance. The need for a complex solution derives both from Dong's false grasp of the underlying reality (seeing propulsion as necessarily pitted against conveyance), and from overlooking a design feature of all efficient watercraft which can be incorporated into the design of a cycling hull (explained below). Accordingly, his patent is not an exception to the wholesale dismissal of the prior art as a set of ironic designs. So we turn to the present invention, which redresses the main failure of the prior art: the need for a design of a cycling hull that targets residual resistance.
The design feature incorporated into all traditional watercraft when reducing residual resistance is the primary goal is a finely graded bow and stern. (Only seeming exceptions result when design considerations other than efficiency are given priority, including when sufficient power is applied to a planing boat or a hydrofoil to ignore the inefficiency of bringing the watercraft into a planing or lift-off mode and keeping it there.) This design feature can be incorporated into a cycling hull as simply as it is incorporated into traditional displacement watercraft: As traditional watercraft effect a fine angle of entry and exit for a displacement hull as it moves through the water, so a cycling hull can set up a fine gradient of entry and exit for the hull sections as they are planted into and pulled from the water.
From one standpoint the analogy is exact: in both cases the hydrodynamic interaction that creates wave resistance—one of the two main factors in residual resistance—is reduced by slowing the speed at which the hull parts and pulls away from the water. From another it is not: the actual speed at which the hull moves relative to the water clearly is not slowed by setting up fine bow and/or stern angles, whereas setting up fine gradients of entry/exit for cycling hull sections does slow the relative speed of the hydrodynamic interaction. In fact, the slowing can be large, 90% and more. For example, setting up the same angle for cycling hull sections as they are planted and pulled as an efficient kayak uses as its angles of entry and exit at its bow and stern produces a 90% reduction in hull speed. (An 18 foot long hull with a 20 inch beam is typical, and will part the water at 7.5% of the speed at which the kayak moves through the water. In the case of a cycling hull that sets up the same angle to plant and pull the hull sections, 92.5% of the relative speed of the hull sections will be eliminated.)
Let's take stock of how a cycling hull with a slow-relative-motion area between the end turnabouts and the point where the hull sections reach full draft compares to both a cycling hull without this slow-relative-motion area and to a traditional watercraft.
First consider a cycling hull without a slow-relative-motion area next to the turnabouts. It will virtually eliminate water friction over most of its “wetted surface,” but has little ability to address wave making and turbulence at the turnabouts. Second consider a traditional watercraft. It can set up a fine angle of entry to reduce wave resistance, but it has limited ability to address water friction and turbulent resistance. But the case of a cycling hull with a slow-relative-motion area next to the turnabouts is different. It will (1) virtually eliminate water friction over most of its wetted surface; it can (2) eliminate most of the wave resistance—where designed to do so, by more than 90%—by slowing the hydrodynamic interface, which will (3) also eliminate most of the turbulent resistance. So a cycling hull with slow-relative-motion next to the end turnabouts addresses all three major forms of hydrodynamic resistance, whereas traditional watercraft and the cycling hull without the slow-relative-motion area are both mostly effective with only one of the three major factors. Furthermore, since wave and turbulent resistance increase exponentially with incremental increases in watercraft speed, the addition of a slow-relative-motion area will theoretically make much more than a 90% reduction in those forms of resistance, given a realistic 90% reduction in the ratio of the speed of hydrodynamic interaction to overall watercraft speed, in many cases.
An unprecedented decrease in hydrodynamic resistance, then, can be produced by combining an insight taken from traditional watercraft and combining it with an insight taken from the work—basically unaltered for the better with respect to efficiency over 149 years—of George Young in 1866.
In short, the principle that wheels utilize to (theoretically) eliminate friction is combined with the principle by which a fine angle of entry (and usually exit) used in good traditional displacement hulls reduces wave-related resistance, and that combination creates a synergistic efficiency that affects reduced hydrodynamic turbulence as well. So a cycling hull with slow-relative-motion hydrodynamics possesses a unique ability to dramatically reduce all major forms of hydrodynamic resistance without either (1) requiring large initial and sustaining power inputs in the cases of planing hulls and hydrofoils, or (2) resorting to submarine hulls with cycling exteriors.
While all cycling hulls have turnabouts at the ends, the present invention uniquely places turnabouts to set up full-draft placement of the cycling hull as it moves along the keel. That placement makes it possible to form a fine gradient for the cycling hull sections as they are planted into and pulled out of the water. It is the use of the turnabouts to create a fine gradient, which thereby affect a slow-relative-motion interface with the water for the hull sections as they are planted and pulled, which will be claimed.

SUMMARY

The prior art does not set up a finely graded entry into and exit from the water for the cycling hull sections, which is analogous to the fine entries at the bow and stern of efficient displacement watercraft hulls. It is by means of this finely graded entry and exit for the hull sections that a cycling hull produces slow-relative-motion hydrodynamics. By setting up slow-relative-motion areas a cycling hull with slow-relative-motion hydrodynamics can reduce almost all of the three major sources of hydrodynamic resistance (skin friction, turbulence, and waves), which no other form of water conveyance can do without either (1) applying relatively large power inputs to begin and sustain a high-speed hydrodynamic interface, as with planing watercraft and hydrofoils, or (2) relying on submarine hulls with cycling exteriors. Because the present invention alone utilizes a familiar and relatively simple technology (“caterpillar track”) to affect its surprising hydrodynamic advantages, the present invention has a unique potential to increase watercraft efficiency.

DRAWINGS Figures

FIG. 1 is a perspective drawing of the present invention from a point of view above and to one side. The waterline depicted therein is not part of the present invention, but is included in FIG. 1 to provide a context for how the present invention will be situated in the medium of its intended use.

FIG. 2 is a perspective drawing of the near lower quarter of the present invention from a point of view above and to one side. FIG. 2 affords a more detailed view of the present invention's components. Being symmetrical in all directions, all of the present invention can be extrapolated from FIG. 2.

Reference Numerals

1 device
10 cycling hull
11 multiplicity of hull sections
12 pivotable connection
20 multiplicity of rotatable end waterline turnabouts
21 first end waterline turnabout with axle
22 second end waterline turnabout with axle
30 multiplicity of rotatable keel turnabouts
31 first keel turnabout with axle
32 second keel turnabout with axle
40 forked frame

DETAILED DESCRIPTION

FIGS. 1-2—Preferred Embodiment

To understand this description fully, it should be read with FIG. 1 and FIG. 2 in view. In referring to this invention and the parts which it comprises, the reference numerals provided above shall be used throughout the following description.
I begin with FIG. 1. There depicted is a perspective view of the present invention as seen from above, to the left of longitudinal center, and from a vantage point in the foreground. (Because the embodiment of the present invention depicted herein is symmetrical in all directions from its center point, references to spatial orientations are projected from the observer's frame of reference. The exception is the vertical dimension, where the waterline establishes the bottom of the vertical orientation.) The preferred embodiment of device 1 comprises these major components: cycling hull 10, multiplicity of rotatable end waterline turnabouts 20, multiplicity of rotatable keel turnabouts 30, and forked frame 40. The bottom of first keel turnabout with axle 31 is lower than the bottom of first end waterline turnabout with axle 21. And the bottom of second keel turnabout with axle 32 is slightly lower than the bottom of second end waterline turnabout with axle 22. The waterline depicted is not part of the preferred embodiment, but is indicated to show how the present invention is situated in the medium of its intended use.
FIG. 2 shows the left lower quarter section of the preferred embodiment from a perspective similar to FIG. 1. This view shows how multiplicity of hull sections 11 is connected to pivotable connection 12, and how pivotable connection 12 is situated to pivot about first end waterline turnabout with axle 21 and first keel turnabout with axle 31, thereby allowing cycling hull 10 to cycle.
Because device 1 is symmetrical around its center point in all directions, device 1, in its entirety, can be extrapolated from the perspective view of one quarter section provided in FIG. 2.

Operation—FIGS. 1 and 2

From the description above it is apparent that the present invention employs a strategy to cycle cycling hull 10 about first end waterline turnabout with axle 21, first keel turnabout with axle 31, second keel turnabout with axle 31, and second end waterline turnabout with axle 32. It is apparent that where cycling hull 10 descends from the bottom of first end waterline turnabout with axle 21 toward the bottom of first keel turnabout with axle 31 (assuming that device 1 moves in the direction of first end waterline turnabout with axle 21) it forms a fine downward gradient. Simultaneously, where cycling hull 10 moves from the bottom of second keel turnabout with axle 32 toward second end waterline turnabout with axle 22, it forms a fine upward gradient. The fine gradients thereby set up between multiplicity of rotatable end waterline turnabouts 20 and multiplicity of rotatable keel turnabouts 30 span the vertical distance between where cycling hull 10 first contacts water and where it reaches full draft under multiplicity of rotatable keel turnabouts 30. The fine gradients that cycling hull 10 thereby forms as it is planted into and pulled out of the water creates slow-relative-motion hydrodynamic interface as device 1 cycles across water.

Advantages

By creating slow-relative-motion hydrodynamic interfaces where the cycling hull is planted into and pulled from the water, the present invention reduces wave and turbulent resistance, which is otherwise unabated at the end turnarounds of a cycling hull. As a result, the present invention implements a strategy to reduce all three major forms of hydrodynamic resistance—skin friction, and wave and turbulent resistance. By comparison the relevant prior art (except that which resorts to submarine hulls with struts to support topside structure) addresses only skin friction. Displacement hulls, on the other hand, can make a mostly effective reduction in wave-making resistance only (by creating a high aspect ratio craft with a fine bow and stern). And planing and hydrofoil hulls can reduce all three major forms of hydrodynamic resistance, but only at the cost of relatively high initial and sustained power inputs (used to raise and sustain these forms of watercraft in planing or lift off mode). A mostly effective strategy to reduce the three major forms of hydrodynamic resistance without requiring high initial and sustained power inputs or resorting to a submarine hull with a cycling exterior, then, comes down to the present invention.

Conclusion, Ramifications, and Scope

The present invention embodies the one strategy that can reduce a majority of all three major forms of hydrodynamic resistance without either requiring high initial power inputs or resorting to a submarine hull with a cycling exterior supporting a top side mounted on struts. It thereby creates a new category of efficient watercraft hull: cycling hulls with slow-relative-motion hydrodynamics set up by situating turnabouts so that they cycle hull sections at a fine angle between the points of first water contact and full draft placement along the keel line.
As no particular means of steering and propelling traditional boat hulls (paddles, oars, sails, skegs, rudders, outboard motors with propellers, inboard motors with propellers, etc.) is essential to the concept of a traditional boat hull, so none is essential to a cycling hull with slow-relative-motion hydrodynamics. Neither is the fact that a cycling hull can uniquely use the hull itself as the means of propulsion—by adding a drive axle to one or more of the turnabouts—an essential feature of the present invention, as the efficiencies gained by adding slow-relative-motion areas to a cycling hull are gained whether or not an “active” or “passive” track is employed. Again, the essential and defining feature of the present invention is the use of turnabouts, as described herein, to set up slow-relative-motion areas where the cycling hull sections are planted into and pulled out of the water when a cycling hull moves across water. It is the placement of the turnabouts so that they affect a fine gradient of entry and exit for the cycling hull sections, analogous to the fine gradient used at the bow and (usually)
the stern of good displacement hulls, then, that forms the essential feature of a cycling hull with slow-relative-motion hydrodynamics.
That essential feature can be used in parallel iterations of cycling hulls with slow-relative-motion hydrodynamics, just as traditional hulls are aligned in parallel iterations to make catamarans, trimarans, and so forth. This is obvious.
What may not be immediately obvious is that a cycling hull can stand alone—Literally—when operated and so form a usable watercraft when not used in conjunction with another cycling hull. But whether such use is obvious is moot, as the same dynamics which allow two-wheeled vehicles—bicycles and motorcycles—to operate without lateral support while in use will be in play when a single cycling hull operates. Accordingly, there is nothing to invent, as the possibility of using a cycling hull as a stand-alone hull has existed all along. (True, a rudder to steer the cycling hull will be essential in the case of operating a single cycling hull, but that will be obvious to anyone skilled in the relevant art, voiding any a claim to that novelty.)
So we are left with the essential feature of a cycling hull as defined in the claim to follow.

Claims

I claim:

1. A cycling hull with slow-relative-motion hydrodynamics, comprising:

(a) a multiplicity of rotatable end waterline turnabouts having a first end waterline turnabout with axle and a second end waterline turnabout with axle,

(b) a multiplicity of rotatable keel turnabouts having a first keel turnabout with axle and a second keel turnabout with axle, said multiplicity of rotatable keel turnabouts being aligned horizontally with and inboard of said multiplicity of rotatable waterline turnabouts in a substantially vertical orientation with the bottom of said multiplicity of rotatable end waterline turnabouts being situated higher than the bottom of said multiplicity of rotatable keel turnabouts,

(c) a forked frame for securing said multiplicity of rotatable end waterline turnabouts and said multiplicity of rotatable keel turnabouts, and

(d) a cycling hull having a multiplicity of hull sections and a pivotable connection by means of which said multiplicity of hull sections can cycle about said multiplicity of rotatable end waterline turnabouts and said multiplicity of rotatable keel turnabouts,

whereby a cycling hull, while cycling across water, creates a gradual descent for its hull sections as they move from first water contact toward full draft placement at the keel line and a gradual ascent for its hull sections as they move from full draft placement at the keel line toward last contact with the water.