Pedal Power ?

[Simon Knight]

There was a  dutch boat called Wuptem participating on the English Raid she was a glass hull of about 20 feet that her owner had fitted out with two unstayed carbon masts as well as a set of pedals that could be used from the helms position.  The pedals could be removed when not in use leaving a metal tube sticking up from the sole.  The pedal drive was taken down through the tube via bevel gears (I think) to a lay shaft.  The drive from the lay shaft was then used to drive the prop shaft via a standard bicycle chain.  She was fitted with a folding carbon fibre prop. 

The beauty of the system was that the helm could propel the boat from his normal position while facing forward and could apply just enough power to move about in a crowded moorings as well as using it during a passage at any angle of heel.

I have been attracted to electric power for use in crowded moorings as I find petrol outboards always seem to die on me at the wrong moment but pedal power seems to offer many of the advantages of electric power with out the problems of battery life.

Any thoughts?

Simon

[Jeremy]

Pedal power is certainly a possibility, the only issue is whether or not there is enough power to drive the chosen hull in the likely conditions.

A big diameter folding prop is definitely the way to go for efficiency, as has been shown by others (Rick Willoughby in Australia has a neat and well-proven system, see here for some info on his pedal system: http://www.rickwill.bigpondhosting.com/)

If your boat can be propelled adequately on about 100 watts of power (around 1/8th hp) then pedal power is a definite option to consider.  If it needs more power than this to manoeuvre safely in the waters you are likely to sail in then pedal power may not be the answer.

Jeremy

PS: 100 watts is pretty much the most a normal, reasonably fit person can sustain, although very fit cyclists can perhaps deliver double this.  My best power over a period of 30 minutes was around 85 watts..............

[Simon Knight]

Jeremy,
Thanks for your comments.  I initially missed your reply as I failed to tick the notify button.

I'm glad that there is at least one other person out there who reckons their power output on a cycle is in the range of the average light bulb (60-80W).  I'm definitely have the power output of domestic light bulb rather than a photoflood.

I am attracted by pedal power as it could be better than rowing (at least my version of rowing) and would mean that I could get rid of the smelly noisy temperamental outboard.  I would propose to only use the pedal power for moving about in crowded anchorages, the rest of the time I would sail.  The other option is to go electric but then there is always the worry that the battery is nearly exhausted coupled with long re-charge times.

Simon

[Jeremy]

One way to build a "pedal outboard" might be to take a look at some of the twisted chain drive systems that people have made.  I made a prototype chain drive (for my electric system) using very thin, 6mm pitch, chain.

I have often thought that such a unit could be made to fit into a wide centreboard case, perhaps with cheek pieces that could be fitted to the case when you wanted to fit the standard width centreboard for sailing.

Here are a couple of links to twisted chain pedal drives that you may find of interest:

http://www.recumbents.com/wisil/hpb/compact_drive.htm

http://microship.com/bobstuart/spinfin.html


Jeremy

[Michael Rogers]

I have followed, with real but (engineering-wise) ignorant interest, the erudite discussion, spread over several threads, about electric outboards, effective props, yulohs, sculling, and now pedal-power as an alternative to either the traditional 'wooden tops'l' or internal combustion as means to move boats when the wind dies. Something occurred to me which probably wouldn't work (would it?), but which is a tiny itch which requires an expert's scratch to go away - or blossom into the cleverest idea since waterproof teabags. Please feel free to laugh uproariously, or construct an embarrassed silence online. Herewith -

A tube containing a shaft which can be rotated by a (detachable) handle at the inboard end, and which sports a (folding) prop at the other. This tube is stowed in the sort of place an oar is kept. For use after unfolding the prop, it is clipped onto a bracket on the transom, and lies astern at the angle of an oar used for sculling, and deep enough to submerge the prop. Instead of waggling it, the handle is turned, turning the prop (need to incorporate gearing??). To steer, swivel to one side or t'other.
Could the length of (leverage exerted by) the handle, possible gearing somewhere (a new use for Sturmey Archer hub gear?) and the characteristics of the prop be arranged so that forward (and astern? - that would be a bonus!) propulsion could be achieved without the handle-turner having to have the physique and stamina of a 12 Metre grinder?

If worth commenting on, I foresee further discussion of human wattage etc.

Just a probably-silly thought.

[Jeremy]

It should work OK.  Speed-wise you need to turn the prop at around 300 to 400 rpm, so, just like a pedal drive, you would need some sort of gearing system with a ratio of maybe 1 to 4 or 5 or so.

I'm not sure how much power you could deliver by driving a rotating handle sideways, but it would probably be more efficient than a traditional scull or yuloh, I think.

Gearing would be the challenge.  Epicyclic gearboxes, like the Sturmey-Archer hub gear, are a bit inefficient, so I would be inclined to accept the penalty of a non-in-line drive and go for either small pitch (maybe 5M or even 3M) HTD toothed belt or a small pitch (6mm or No.25) chain.  The belt drive has the advantage of being grease and maintenance free.

One thing that would need to be sorted would be a way of taking the torque reaction.  Some sort of stern-fitted rowlock with an anti-rotation peg would be needed, or, perhaps, a rectangular rowlock and a square tube for the drive unit.

For a propeller, then I'd opt for something like the one I've made for my electric Winsome: