In the latest SCA it's noted that pedal drives were used very successfully in the first R2AK. I'm at least a little familiar with a couple of these, but would like to learn much more about them, particularly pedal to propeller approaches that were used. How well did they work? Commercially available units?

Any and all info anyone can provide will be appreciated.

Thanks, Scot

Scot, I have used the SeaCycle prop drive. They are available to purchase as a drop in unit for aprox. $500. I believe they are ok but found the plastic body to create a lot of drag. It is airfoil shaped but thick, I suppose they that to be that thick otherwise they would have made them thinner. It is a twisted chain style. Otherwise it would propel the seacycle cat at 3-4 mph at a relaxed pace 50-60 revs per minute. It could also maintain this into a 10-15 mph headwind so it had good "bite". But push it over 4 mph and you are done pretty fast. It topped out for me at aprox 7 mph, well under the claim on the web site. This is just from my experience, others may have found it to be different. I had 2 units and both were the same and using both with two folks speeds increased by 1 mph.
Roger

Thanks Roger. I've seen the SeaCycle on the web, and also note that one of the R2AK's competitors tried it but decided to use a different pedal to prop drive that they found faster - I think it involved a cable drive system. I've also seen a little about the SpinFin drive. It looks good, but it's not clear whether they are available.

The "Pedal Powered Boats" thread on the BoatDesign.net forum has a very long discussion about pedal drives.

What I found interesting was that a spring steel shaft with a prop on the end will self stabilize. No need for a strut to hold it in place. If it hits an obstruction it will just "walk" over it.

Scott,

Rick Willoughby is the guy to know about pedal drives. He's an Australian that has been working for years to refine his boats and drives to be the most efficient. I helped a couple Seattle teams with their pedal drives for the race this year, which mostly amounted to convincing them to use Rick's designs. Team Turn Point also had a Rick W inspired drive.
I have one of Rick's single racing pedal boats which I've raced in local Sound Rower's races. I crewed on Puffin, in leg one, which had one Rick W drive, and one Seacycle drive.
Rick is on the prototype phase of a commercially available drive unit. Hopefully it will be available this winter. Let me also say that Rick is very generous in sharing his knowledge and time. He is retired and does not charge for his work.
I'm more than happy to answer any questions, or put you in contact with Rick or parts suppliers. matthewjohnson1 At hotmail
Matt

Thanks Matt. I'm sending a message to Rick, copy to you. Depending on his response, I may get in touch with you regarding parts suppliers.

Hi Scot,
I have two of Rick's propellers and two stainless spring steel shafts for sale cheap if you are interested. Rick is great! He helped us out a lot with answering many questions about pedal drives for our boat. I would ask a couple questions in an e-mail and he would generously reply with a couple paragraphs!

Did you use Rick's drive designs and parts for human power on your cat?

No, we ended up desgning our own outboard leg type system based around our optimum prop size and prop rpm...found using Javaprop. (With guidance from Rick). I really like the flex drive system though...seems like it worked great on team searunners boat and has less frontal area/drag than our system. Felix has a lot of bridgdeck clearance and so the outboard leg made it easier for us to swing a bigger prop from the cockpit (higher efficiency) and still get it out of the way quickly for sailing.

I am a huge fan of pedal power and it puts a smile on my face everytime I pedal out of the harbor. Every small sailboat should ditch their outboard and setup a pedal drive!

Funny story about this: A friend has been sailing on Felix with his son a couple times and now has the sailing bug. He finds a boat that he really likes and takes his son with him to check it out. His son isnt so excited about the boat for some reason and so the dad asks his son afterward what was wrong with it. Son says "but dad it dosn't have a pedal drive"

Hi Scott,
Here is a screen shot showing a cross section of the pedal drive we made. It consists of two AngleDrives connected by a stainless shaft surrounded by a fiberglass strut. The kickup pivot is on the same axis as the top bevel gear which allows the chain to keep tension while retracted. To retract it you pull a small uphaul line. To lower it you let go of the line and start pedaling.

We have a 20" RC aircraft prop on it now but we could gain another ~ 5% efficiency by cutting a custom prop.

Hope that helps