[hpv-boats] Auxilliary pedal power

[Roger Boden]

Mark

Thanks for this.  I'm buying the H20 Sport which has the large open cockpit.

Your solution sounds gloriously simple.  I do indeed want to be able to use the bike on land.  I'm planning to put a timber seat across the centre of the cockpit which, among other things, will carry the mainsheet traveller,  I thought I might have a front wheel quick-release axle mounted on it: I would attach the front forks to that and have the rear wheel on the bike stand, with maybe lines from either side of the boat to hold the bike vertical.  If my schoolboy maths is correct, the cable shaft (assuming a smooth curve) would have a radius of approx 1.3mtrs which should fit easily in the cockpit

My original thought was to drive the propeller with a chain, but that would presumably involve two sets of direction-changing cogs, which I guess would take quite a toll on the efficiency of the mechanism.  Do you have any sense of how efficient would a cable shaft turning through 90 degrees would be, compared with a chain and cog mechanism?

Thanks again for your help.

Roger

-----Original Message-----
From: hpv-boats-bounces at bikelist.org [mailto:hpv-boats-bounces at bikelist.org] On Behalf Of Mark Vermilion
Sent: 29 September 2010 12:56
To: Human
Subject: Re: [hpv-boats] Auxilliary pedal power

Roger,

It sounds like you are going the route of using a bicycle because you  
wish to disconnect the cycle for land use, no? Do you have the H20 or  
Hunter 20 Fox C?

I'm not sure if it will work for you, but in six weeks I will have  
available to the market a two meter flexible cable shaft engineered  
for aquatic pedal use. It has a rating of 200 in.-pounds torque, made  
of 316 stainless wire, and flexible enough to handle a 90 degree turn  
over distance.

If you used a stationary bike stand, I can envision fixing (weld) a 26  
mm long x 12 mm diameter post to it's spinning axle. You might lose  
efficiency between your tire and this axle, but I am going with your  
desire to use a bike. Then it is only a matter of attaching the  
shaft's female coupler with a 1/4 inch (6 mm) cotter pin onto the  
post, and gradually over a distance of two feet turn the cable to the  
stern. It looks like on either boat you could drill a hole in the  
stern just above the deck, off center and away from the rudder. You  
would fabricate a solid shaft and shaft support at the gradual angle  
you need to submerge the prop. Use an Igus plastic bearing in the  
hole, and attach the cable to the solid shaft just inside the boat,  
again using a simple cotter pin for quick disconnect. This external  
shaft assembly could easily be detachable when not needed.

The cable has a nylon tube around it in order to fix the cable and not  
allow it to slither, You could mount the cable either permanently with  
closed clips or temporarily with clips that can be opened along the  
base of the cockpit at the vertical surface.

Since your road bike has a free spinning axle, you would not be able  
to pedal in reverse.

I do not yet have a price for the cable, but I am sure it will be less  
than $250 US delivered, possibly even to Europe. This system is not as  
elegant as the ShuttleBike, but a lot less expensive.

I have tried to attach a crude sketch, but the email kicks back  
because the message is too large. Write me directly if you would like  
to see it.

Mark A. Vermilion

Marco Polo Boats, Inc.
Exploring the past and future of small boat design
1911 Smallbrook Drive
Troy, Michigan 48085
USA

Tel & Fax   1-248-434-4187
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