Pedal drive mechanism for a human powered boat

Abstract

A pedal drive system for a human powered boat includes a series of idlers regulating chain means such that when a pedal drive sprocket applies torque, said chain means gets fed through the series of said idlers on the non-tension side of said drive system from a driven propeller shaft sprocket to said pedal drive sprocket, said driven propeller shaft sprocket located substantially below said pedal drive sprocket and skewed such that its rotation axis is at right angles to the pedal rotation axis. While said chain means is fed from said driven propeller shaft sprocket to said pedal drive sprocket, it is held in place, fed smoothly and easily, and held under adequate tension as to prevent said chain means from skipping by the angular alignment and orientation of said idlers and tensioning means for said chain means with the natural twist of said chain means.

Description

BACKGROUND OF THE INVENTION

[0001] In 1984, a pedal powered hydrofoil called the flying fish was the first known hydrofoil to achieve successful flight under human power (International Human Powered Vehicle Association. HUMAN POWER, FALL, 1984) (SCIENTIFIC AMERICAN, 1985). The strut and drive system consisted of a drive shaft in the plane of the pedal crank connected to a propeller shaft by a #25 or ¼ pitch chain twisted into a “mobius”. This was the first known public use of a “FIG. 8” drive.

[0002] Due to the fact that the chain was operated near its breaking point, it would only be able to be used in racing. Also the Flying Fish type setup used two chains: one for the strut going down into the water, and one that connected the pedal sprocket to the driven sprocket on a jack shaft. Boats using this system would require extra power needed to operate the extra shaft and bearings, and have the additional concern of having to run extra moving parts

[0003] There have been many of these systems built through the years, but there were many problems associated with them. Three of the biggest have been that the struts were too fat, the breaking point was unpredictable at best, and that chains and sprockets wore out too fast.

[0004] Another common example is to be seen in U.S. Pat. No. 5,011,411; PEDAL OPERATED WATERCYCLE

[0005] Although the drive unit of this boat would operate comfortably in a twisted environment, it would often break due to not being heavy duty enough. For that same reason, it would wear out faster.

[0006] In a non constantly tensioned system, if a single bolted idler or jack shaft were to get repositioned, or if the drive system was to experience a chain which lengthens, the system will jam, skip or undergo teething problems. Chains lengthen or ‘stretch’ due to initial breaking in, temperature changes, wear, etc. A constant vigil must therefore be kept on anything other than self-tensioning drive in order for the system to work properly.

SUMMARY OF THE INVENTION

[0007] Newer type bicycle chains (#43; ½ pitch) are currently available on the market that lend themselves to being operated while twisted. there are now available a full size bicycle chain types that can be twisted 90 deg over a distance of some 18 inches. This development allows full size chain to be used in struts almost as narrow as they would need to be for the thinner lighter duty chain. Bicycle chain has 2 to 2.5 times larger tensile strength than #25

[0008] It is absolutely essential that the drive unit be able to provide the MOST TORQUE POSSIBLE with the LEAST OPERATIONAL DRAG POSSIBLE.

[0009] If propellers were analyzed for drag where they do the most lifting, (average=0.8 [tip diameter]) it would be found that the faster the rotational velocity, the more drag there is. The extreme would be where there's infinite velocity, no advance, and therefore infinite surface drag. This is due to the increased surface friction of the higher reving propellers, and is arrived at by the equation: 1$F_d={C_d\left(\frac{1}{2}\right)}_{\rho }{V}^{2}S$

[0010] where Fd drag; Cd=drag coefficient [constant]; ½ ρ cancels out near the water surface; v=velocity note that the term is squared; S=surface area.

[0011] On blade angles, the formula that applies is 2$V\left(final\right)=\frac{V\left(boat\right)}{\sin \left(\beta \right)}$

[0012] where V(final)=blade velocity, V(boat)=boat velocity; B=blade angle at a particular diameter. Suffice it to say that the lesser angle B is, the faster the blade element has to go in order to get the same advance.

[0013] The full proof is very long, but the general idea is that when the velocity increases, force increases to the square!

[0014] Therefore, slower turning propellers with higher pitch to diameter ratios have less drag, but the bad news is that they have increased torque. The extreme is where there's zero velocity, infinite advance, and, of course, infinite torque.

[0015] My invention is the first daggerboard type drive that can use regular size bicycle chain. It can withstand two and a half times as much torque as those units that employ #45 ¼ inch pitch chain.

[0016] For dependability, a user of a pedal powered drive unit will want to spend as little time as possible fixing, tinkering and adjusting the unit and the most time pedaling out on the water. My invention promotes this in that it is the first one that has a self-tensioner. Chains will stretch due to eventual wear, but more likely because of factors like even temperature change. My invention solves the reliability problem by constantly tensioning the chain in a way somewhat similar to a regular bicycle, except in three dimensions instead of two.

[0017] In order to prevent the chain from derailing (as well as have the lowest drag as possible), the idlers must each be parallel to the pivot plane of the chain, perpendicular to path of the chain pin/roller axis. Therefore, in a twisted chain drive, they must be tilted the same degree as the twist. The leeward idlers in this invention are all matched up to the twist in three dimensions, and each idler and sprocket is surrounded by guide plates.

[0018] Therefore, It is the object of this invention to provide a rugged durable lightweight compact human powered boat drive system that lends itself to installation as a kick-up daggerboard, that lends itself to a multihull installation, an economical installation, a high performance installation, an integrated human powered hydrofoil strut installation, a high torque (large propeller pitch) installation, or any combination of the above.

[0019] It is another object of this invention to provide a self-tensioning drive system wherin it requires less adjustment, maintenance,

[0020] It is another object of this invention to provide a drive system that can be framed in as a composite jacket that supports the pedal crank bracket above the waterline, and houses the propeller shaft mount, chainpath, internally in a smooth faired streamlined case below the water.

[0021] It is further an object of this invention to provide drive system that is entirely maintenance free, and wherein the entire drive system lends itself to being totally waterproof wherein the interior workings may be non-corrosion-resistant, and therefore of lesser expense.

[0022] It is another object of this invention to provide a drive with a narrower strut, and therefore faster speeds.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Moving now to the drawings, FIG. 1 shows an orthographic front view of the mechanism with the top chain shown as centerlines for better clarity

[0024] FIG. 2 shows a perspectuive upper parts and the integrated jacketed streamlined lower portion.

[0025] FIG. 3 shows a perspective of the driven shaft and allied parts and how they fit into the lower part of the streamlines jacket.

[0026] FIG. 4 shows a perspective mostly from the top of the mechanism showing how the drive sprocket fits in with the tensioner arm, how the anti derail parts fit around the tensioner arm, and how the top region is oriented with the rest of the mechanism.

[0027] FIG. 5 shows the orthogonal top view of the whole drive unit with the drive sprocket section cut off demonstrating the degree of twist in the tensioner arm.

[0028] FIG. 6 is an exploded view showing the details of the tensioner arm.

[0029] FIG. 7 is an exploded view showing the detail of the drive sprocket size adjustment.

[0030] FIGS. 8 and 9 shows how different settings of the size adjustment accommodate different sprocket sizes.

[0031] FIG. 10 shows the exploded detail of the upper guide plates on the tensioner arm and upper stationary idlers

[0032] FIG. 11 shows the guide plates and washers around the driven sprocket and idler

[0033] FIG. 12 is a perspective schematic of the positions of the rollers as if they were oriented in an opposite twist condition as they progress through the three dimensional chain path

[0034] FIG. 13 is a perspective schematic of the positions of the rollers as if they were oriented in an similar twist condition with the tilt of the arm in the other direction from the one in FIG. 12.

[0035] FIG. 14 is a orthographic top view diagram showing positions of all the idlers and sprockets, and the relationship of the twist throughout the mechanism.

[0036] FIG. 15 shows an alternative embodiment of the tensioner arm assembly which features a single idler in lieu of two.

[0037] FIG. 16 shows an alternative embodiment of the drive unit with the chain path entirely external, and coordinated with a long shaft

[0038] FIG. 17 shows an alternative embodiment wherein the chain and tensioning components are all contained entirely within in a waterproof casing.

DESCRIPTION OF A PREFERRED EMBODIMENT

[0039] The following preferred embodiment and alternative embodiments are put forth to give an idea of the invention, but by no means do they represent the only form this invention would take.

[0040] A pedal-powered drive mechanism supported by frame and jacket 1 in [FIG. 1 and 2] has streamlined sections 2 in [FIG. 3 and 4] for the strut region below the waterline 3. The drive sprocket 4 is driven by pedals 5 which pulls tensioned chain 6 through a narrow tube/passageway 7 encased within said strut region 3 from driven sprocket 8. The leeward non tensioned chain 9 is fed from said drive sprocket 4 through upper positioning idler 10 out again to upper tensioning arm idler 11. Said leeward chain 9 proceeds through assembly of idler arm 12 in an outward protruding plane to lower tension arm idler 13, then back to lower positioning idler 14. Said chain 9 progressing through idlers 10, 11, 13, 14 is kept from derailing by washers and retaining plate means 39, 40, 41.

[0041] Said leeward non tensioned chain 9 then continues down through said narrow tube/passageway 7. The driven sprocket positioning idler 15 receives said leeward chain 9 in a close proximity to said tension chain 6 and feeds it to the perimeter of driven sprocket 8 in [FIG. 4]. The propeller shaft 16 supports the propeller 17. Access to said propeller shaft 16, propeller shaft keeper bearings 18, and driven sprocket 8, both sprocket 8 and idler 15 preventing derailment by washer and guide plate means 42, and 43, are covered by waterproof access cover 19. Said propeller shaft 16 is kept waterproof by shaft—seal 20.

[0042] The said tensioner arm 12 in is supported from said frame 1 by a boss 21 in [FIG. 5], supporting around tensioner arm pivot pin 22 so that said tensioner arm 12 can swivel up and down. Adjustments to said leeward chain 9 can be made by rotating chain adjustment cylinder 23 in [FIG. 6] so the lower idler mounting bolt hole 24 can be repositioned enough to compensate for at least 2 chain link lengths. Said position of chain adjustment cylinder 23 is held tightly by the chain adjusting cylinder mount clamp 25. Said tensioner arm 12 is pulled towards said frame 1 by a spring means 26 bolted to said frame 1 by fastener 27 and hooked to said tensioner arm 12 through guide holes 28. Teething caused by propeller reversal, stops, etc., can be compensated for by squeezing a hand brake (not shown) which actuates push cable 29, pulling in said tensioner arm 12 by means of cable with swaging 31 secured to said arm 12, thereby increasing tension. Said cable and swaging 31 is secured to said tensioner arm 12 by fastener means 32. Push cable is secured to said frame 1 by means of fastener 33.

[0043] In order to accommodate drive sprockets of different sizes, and thus change the gear ratio, the position of the pedal axis is changeable while not affecting the tangential relationship of said tensioned chain 6 with said drive sprocket 4 and said driven sprocket 8 proceeding through said narrow tube/passageway 7. A cylindrical sleeve 35 in [FIG. 7] has outside diameter to match inside diameter of clamping ring 36 which integrates into said upper frame 1, and has a single axial wall split split 37. Said cylindrical sleeve 35 has substantially non concentric inner and outer diameters while their center lines are parallel.

[0044] The inner diameter of said sleeve 35 is the same as and accommodates the outer diameter of the pedal bracket shell 38 which supports the pedal bracket cartridge (not shown).

[0045] Adjustment for a small sprocket 4a in [FIG. 8] has said cylinder 35 rotated such that said pedal bracket shell 38 is close to the centerline of said tensioned chain 6, while for large sprocket 4b, in [FIG. 9], said cylindrical sleeve 35 is rotated such that said bracket shell 37 is further away from said tensioned chain 6 centerline.

[0046] Said leeward non tensioned chain 9 in [FIG. 10] is kept from derailing between said drive sprocket 4 and said tensioner arm 12, as well as between said arm 12 and driven sprocket 8, by plates 39 mounted over said upper and lower positioning idlers 10 and 14 respectively, and to said frame 1. Derailment of said chain 9 progressing through upper and lower tensioning arm idlers 11 and 13 on said tensioner arm 12, is prevented by inner and outer plate means 40 and 41. Derailment from said driven sprocket 8 and said driven sprocket positioning idler 15 in [FIG. 1]) is performed by washer means 42 and guide plate means 43.

[0047] Preferred Operation

[0048] The chain can operate in either opposite, double opposite “MOBIUS LOOP” twist fashion as shown in [FIG. 12] or single twist fashion as shown in [FIG. 13] (4 combinations), The advantage double opposite being that said chain wears evenly to right/left twist, and single twist taking up less space in said tube 7.

[0049] As chain tension 6 is caused by applying torque to the drive sprocket 4, the chain wraps around said drive sprocket 4 until it is fed to the leeward non tensioned region 9. Said leeward chain 9 is first fed through upper idler 10 and out to upper tension idler 11 in the same plane defined vertically by centerline 59 and said drive sprocket 4. Although this first leeward section of chain 59 continues to said upper tension arm sprocket 11 in the same plane as said centerline 59, and said drive sprocket 4, it twists between said idlers 10 and 11, due to idler 11 being tilted horizontally outward. After said chain 9 is fed through said upper tension arm idler 11, it is fed into another plane defined by the chain centerline 59 at the upper bound, and chain centerline 60 at the lower bound. Said centerline 59 is between idlers 10 and 11, and centerline 60 is between idlers 13 and 14. Chain in said centerline portions 59 and 60 is twisted; Chain in portion 61 between idlers 11 and 13 is not.

[0050] Said idler 10 runs in the same plane as said drive sprocket 4. The plane of said idler 14 is tilted, although in a substantially vertical plane outward while the fed chain is as close as possible to being tangent to a common vertex/origin 67 in [FIG. 14]. The degree to which this plane is angled is defined by the following formula: 3$\alpha =\frac{90x}{l}$

[0051] where α is the angle from said drive sprocket plane 62 (or the driven sprocket plane 63 in [FIG. 14] depending on which origin is preferred), x is the distance from said idler centers of 14, and 15, to the center of said drive sprocket 4 (or said driven sprocket 8), l is the distance between said drive and driven sprockets 4 and 8.

[0052] The portion of chain centerline 60 is fed from said idler 13 to said idler 14. Said portion 60 is along centerline 64 in [FIG. 14] and twists so that said portion 60 in [FIGS. 12 and 13] is heading substantially vertical after it is fed through said idler 14.

[0053] The above formula dictates the angle at which idler 14 is tilted in vertical plane; the lengths of said portions 59, 60, and 61 as well as the degree of tilt of idlers 11 and 13 are dictated by how large that angle needs to be.

[0054] Said leeward chain 9 twists as it travels through said center line portion 68 such that by the time it reaches said driven sprocket 8, after being fed through said driven sprocket positioning idler 15, it is in a plane 90 degrees from plane of said drive sprocket 4.

[0055] In order for said driven sprocket positioning idler 15 to be placed most optimally, it is slightly out of plane from said plane of driven sprocket 8, with its plane-twist-angle 65 in [FIG. 14] being defined by the above formula. After the chain follows around said driven sprocket 8, it completes a cycle and again becomes said tension portion 6 twisting 90 degrees between centerlines of said driven and drive sprockets 8 and 4.

[0056] Alternative Embodiments #1

[0057] An alternative Embodiment for the tensioner arm 12 in [FIG. 15] is where there is one large diameter idler 44 in lieu of idlers 11 and 13, and said tensioner arm 12 has one lug on it's end to fit said chain adjusting means 45.

[0058] Alternative Embodiment #2

[0059] Another alternative embodiment of this drive mechanism is where the frame 1 is a trunk in [FIG. 16] which supports the components entirely externally. Upper positioning sprocket 10 is supported by upper positioning sprocket idler boss 46. Lower positioning idler 14 is supported by lower positioning idler boss 47. Tensioner arm is supported by tensioner arm boss 48. Drive sprocket adjustment sleeve 35 is supported by adjustment sleeve boss 49. Driven sprocket positioning idler 15 is supported by driven sprocket positioning idler boss 50. The propeller shaft 16 is substantially long, and is held in place by an also substantially long keeper tube 51 and supported by occasional bushings (not shown). Said shaft and keeper descends past the waterline 52 in a gradual manner wherein there is low water resistance and only slight angle from the horizontal. Said keeper tube 51 is connected to said trunk frame 1 by clamping collars 53,

[0060] Alternative Embodiment #3

[0061] Still another alternative embodiment consists of the frame and jacket 1 entirely encapsulating the components such that the drive mechanism is waterproof. A drive shaft 54 is driven by taper-pinned-pedals 55, with the drive sprocket 4 affixed in center of said shaft 54. Said shaft 54 is supported by water-sealed bearings 56 which rest in grooves 57. A water sealed cap 66 mounts said bearings 56 in place while keeping the resulting parting line watertight. Access to the tensioner arm 12 and the rest of the upper components is kept watertight by waterproof access cover 58.

[0062] Alternative Embodiment #4

[0063] An Alternative embodiment for said sleeve 35 in [FIG. 4] and/or water sealed bearings 56 and grooves 57 in [FIG. 10] is where the sleeve is graduated or mechanically indexed to mark the optimum sprocket positions, or the water sealed bearing package is faceted to insure bearing alignment of each side when different size sprocket/shaft assemblies are installed

[0064] Alternative Embodiment #5

[0065] To further prevent skipping or teething while coasting, or when the drive is pedaled in reverse, a ratchet and prawl freewheeling device can be installed in concert with or in lieu of the system with the handbrake, push cable 29, and swaged cable 31 in [FIG. 3].

Claims

1) A pedal drive system for a human propeller powered boat which consists of: a framing means with pedal axle keeping means supporting pedal axle assembly means operatively connected to a drive sprocket means, a mounting bracket means integrated into said framing means wherein drive system is mounted to boat frame a propeller shaft operatively connected to a driven sprocket, said propeller shaft being located substantially beneath said pedal axle assembly, and skewed at right angles to it, a chain means of the appropriate size to drive bicycles, or any reasonable size thereto, said chain being oriented in a twisted three dimensional form, a self tensioning means whereby tension is kept on said chain means while being adequately three dimensionally geometrically aligned wherein said chain means glides with minimal resistance between the two said skewed shafts and operates in a twisted condition.

2) the pedal drive of claim (1) wherein said tensioning means is a rack or plate means operatively connected to said framing means and including a swivel axle pin means and tensioner means wherein the centerline perimeter of said chain means expands when said tensioning means is actuated

3) the pedal drive system of claim (1) wherein said pedal axle assembly keeping means supports said drive sprocket means in an overhung condition, said drive system of claim (1) wherein the incoming and outgoing chain means are fed through an opening through a streamlined casing, said casing being the lower part of said framing means, said drive system of claim (1) wherein said streamlined casing is lined up with the upper portion of said framing means in an offset condition wherein the centerline of the segment of chain means that is under tension lines up with the incoming tangent of said drive sprocket means, and the outgoing tangent of said driven sprocket means, wherein planes of said drive and driven sprockets are substantially perpendicular to one another, and wherein the intersection of said planes is the centerline of said chain means under tension while said chain means under tension is twisted between said drive and driven sprocket means an idling means set at the top and bottom of said streamlined-casing-opening wherein the entering and exiting centerlines of said chain means are very close together wherein said streamlined-casing-opening can be very small, and therefore allowing said streamlined casing to be very thin, a streamlined bulb encasing said driven sprocket and idling means including bearings for said idling means, bearings for said driven shaft, access door, and water seals for said door and said shaft.

4) the drive system of claim (1), (2) and (3) wherein instead of said frame being offset, it contains said casing opening in an aligned condition, said opening including tensioning means, and wherein instead of pedal axle assembly keeping means holding drive sprocket means in overhung, said drive sprocket is supported between bearings, said tensioning means being located within upper part of said casing opening.

5) The pedal drive system of claims (1), (2), (3) and (4): wherein said tensioner rack or plate means is an arm with said swivel pin at one end and said idler means being a flying idler means at the other, wherein said swivel pin mounts into and is supported from said upper portion of said framing means, wherein said upper frame portion supports two stationary mounted idler means: one being said idler means at top of said streamlined-casing-opening, and one above it such that said chain means wraps around said drive sprocket means, wraps around said upper idler means, sends chain means out said arm, through said flying idler means, back in again, around said lower stationary idler, and down through said streamlined-casing-opening, wherein the section of said chain means, fed from said drive sprocket means through said upper stationary idler means and through out-fed segment of said chain means centerline at the top of said arm, are all substantially in plane with said drive sprocket, wherein said flying idler means being substantially side tilted thereby causing the out-fed chain means segment at the top of said arm to be twisted while said chain means centerline in said segment is still substantially within the plane of said drive sprocket, said twist being a result of said frame-fixed stationary mounted idler and flying idler means being out of plane while the axis of intersection of those planes is the centerline of said segment of said chain means on top of said arm, wherein the segment of said chain means feeding in from said flying-idler means from below said arm is also twisted, realigning itself between the different planes of said flying-idler means and said stationary mounted idler means at the top of said streamlined-casing-opening, wherein the degree of said flying idler means tilt matches the requirement of the bottom tangent of said flying-idler means lining up substantially to plane of said idler means at top of said streamlined-casing-opening wherein the planes of said flying idler means and said idler means at the top of said streamlined-casing-opening intersect along the centerline of said chain means returning from said flying idler means to said idler at top of streamlined-casing-opening, and wherein said segment of chain returning in from flying idler means is twisted from said flying idler means plane to said plane of said idler means at top of streamlined-casing-opening. wherein the plane of said idler at top of streamlined-casing-opening being substantially dictated by the degree of twist in said chain means at that particular distance between said drive sprocket tangent and driven sprocket tangent, planes of said drive and driven sprockets being substantially at right angles to one another, wherein said idler means at the bottom of said streamlined-casing-opening is tilted enough to have its axis remain perpendicular to the pivot plane of said chain means at that particular degree of twist in said chain means between said driven sprocket means, and said drive sprocket means, planes of said drive and driven sprocket means being substantially at right angles to one another.

6) The pedal drive system of claim (5) wherein swivel pin axis of said tensioner arm is tilted slightly towards the axis of said lower stationary idler from the plane of said drive sprocket and said upper stationary mounted idler wherein said flying-idler means translating about the arc of arm-swivel between it's established extremes, creates a balance between lining up outfeed of said chain means centerline to plane of said upper stationary mounted idler, and lining up infeed of said chain means centerline to the plane of said lower stationary mounted idler.

7) The pedal drive system of claim (5) wherein said swivel pin center is located above or below a horizontal reference line with respect to two said stationary mounted idler means while the horizontal center of said flying idler means is located to the opposite height from said horizontal reference line as said swivel pin center wherein a slight movement about the arc of swing of said flying idler means towards said horizontal reference line lengthens said chain means perimeter thereby causing a tensioning condition in said chain means.

8) The pedal drive system of claims (1) and (5) whereby tension is actuated substantially by the weight of said flying idler arm.

9) The pedal drive system of claim (1) and (5) wherein instead of gravity the tensioning condition is substantially actuated by spring means or a combination of spring and gravity force.

10) The pedal drive system of claims (1) through (9) which includes a flying idler position-adjustment means wherein the changing length of said chain means centerline can be accommodated for, and wherein the position about its travel arc of said flying idler means arm of claim (7) can be repositioned.

11) The pedal drive system of claims (1) through (10) of wherein said chain means perimeter adjustment is achieved through having flying idler means mounted on a clamped non-concentric-centered sleeve wherein rotation of said sleeve relocates the flying idler mount position.

12) The pedal drive system of claim (10) of wherein said chain means perimeter adjustment is achieved through having flying idler means mountable at different bolt hole locations.

13) The pedal drive system of claim (10) of wherein said chain means perimeter adjustment is achieved through having flying idler means mounted with a combination of bolt hole locations and adjustable location means.

14) The pedal drive system of claims (1) through (13) wherein the range of said swing arc has adjustable/setable limiting means wherein at one extreme, said limit can be set to keep the glide drag of said chain means low, and at the other extreme, said limit can be set to prevent said chain means from skipping.

15) The pedal drive system of claims (1) through (14) wherein the tension of said chain means can be manually actuated during operation wherein the one limit of extreme can be adjusted to keep drag of said chain means low, and the other extreme can be actuated to prevent said chain means from skipping, especially when said pedal drive system is pedaled in reverse.

16) Pedal drive system of claims (1) through (15) which includes a freewheeling ratchet and prawl mechanism wherein sudden stop or pedal reversal of the pedals will not cause said chain means to teeth, skip or derail.

17) Pedal drive system of claim (1) through (16) which includes guide/guard plates surrounding both sides of all idler means, inexcessable paths, driven sprocket, and the like wherein said chain means will be guided back onto respective idlers or sprockets in the event of derialment, skipping or teething.

18) The drive system of claims (1) through (17) including a repositioning means for axis of said pedal axle keeping means wherein pedal to propeller gear ratios can be changed by engaging different sprocket sizes to said pedal crank while still maintaining alignment of said chain means centerline between said drive and driven sprocket means as well as alignment substantially along said narrow streamlined-casing-opening.

19) The pedal drive system of claim (18) wherein said pedal axle keeping means is contained within a larger cylindrical sleeve having non-concentric inside and outside diameters while center lines of surfaces of said diameters are parallel, such that when said sleeve is rotated, the position of said pedal axle keeping means is repositioned, while said pedal axle keeping means centerline maintains its necessary parallel condition, Wherein said sleeve is adjusted by rotating such that for smaller sprockets, position of said pedal axle keeping means is close to said tangent of incoming chain means and said drive sprocket means, and for larger sprockets, said pedal axle keeping means is farther away from said tangent, wherein said sleeve position is locked in place by means of a clamp tightening and by virtue of a split in said non-concentrically centered cylindrical sleeve

20) The pedal drive system of (18) wherein there are graduations for different sprocket teeth numbers or keys, notches, or mechanical indices or the like, wherein alignment of such devices corresponds to the optimal position of the teeth number of a particular mounted sprocket.

21) The pedal drive system of claim (4) through (17) wherein said drive sprocket is supported and sealed inboard of the base of the pedal cranks between two watertight bearings, wherein said bearings are mounted in the walls of said casing, and covered by a watertight housing, and including watertight seal around all access ports, wherein said tensioning means is supported from one or both walls internally, and is sealed watertight, wherein all adjustments and shafts are sealed thereby completely encasing said pedal drive system in a watertight jacket,

22) The drive system of claim (21) wherein bearings are kept aligned from side to side in a corresponding set-pattern condition by splines, keys, facets, segment molding or the like, whereby bearing centerlines will automatically align themselves according to different sprocket size settings, and wherein when different sprocket assebly sizes are installed, said bearings can not be installed misaligned.

23) The drive system of claims (1) through (20): wherein except said drive system is completely external including said driven sprocket means said shaft means and, shaft idler means, wherein framing means consists of a rack or trunk means supporting all sprocket means and idler means by lugs mounted on said rack or trunk means whereby the whole system operates in a dry environment, wherein said driven propeller shaft is began generally beneath said pedal axle keeper, and is substantially long and entering the water at a gradual angle, wherein said long shaft is supported by a shaft keeper means including bushing means, wherein said keeper means is mounted at the bottom of said trunk or rack means