Pedal Powered Boats

Discussion in 'Boat Design' started by Guest625101138, Jul 14, 2008.

  1. Submarine Tom

    Submarine Tom Previous Member


    Welcome to the forum.

    It took me two years to figure out how to post pictures!

    I'd say you're doing pretty well.

    Jeremy, I acquired a bunch of "time expired" helicopter rotors yesterday including a complete set from a Robinson R-22.

    They may be just the ticket for my project. I'll have to crunch the numbers.

    How's your build coming along?
  2. Gib Etheridge
    Joined: Nov 2012
    Posts: 28
    Likes: 1, Points: 0, Legacy Rep: 13
    Location: BC Canada

    Gib Etheridge Junior Member

    I chose the images in my first post not just to familiarize myself with the posting technique but to establish my credentials as an amature boat designer/builder.

    If you click on the Flickr URL in my post you'll get the Flickr page where you can click on the "21' round bottomed double ender" set. There, if you're interested, you can view thumbnails showing the build. The thumbnail at the bottom of the post is another boat I designed and built previously. There have been a few others.

    Having demonstrated that I am capable in that respect here's some more info.

    Now that I am retired and my kids are on their own and the mortgage is paid I have the time to build a boat specifically for rowing from Victoria, BC, to the Alaska border, something I've wanted to do since before my kids were born 30 years ago. In reality my shoulders have degraded to the point that I am no longer able to row for extended periods. Well, if I can't row I can pedal. In fact, I would rather not travel that far in reverse anyway, and since I've been interested (obsessed) with pedal power for several years now it makes sense to pursue the subject more seriously. I was thrilled to come across this forum and am very impressed with the knowledge, skill and generosity of the members.

    Here's my proposal. I want to build a boat quite similar to Ken Basset's "Liz".

    His hull is about 18' LOA X 17' LWL X 36" beam X 32" Beam at WL X about 85 lbs., as strip built by the very capable people at Newfound Woodworks.

    The hull I propose is more like 21' LOA X 20' LWL X 42" beam at sheer X 39" beam at WL X 200 lbs. empty, perhaps 500 lbs loaded. It will be decked fore and aft with the below decks space being divided into 4 seperate watertight storage and flotation compartments, 2 forward and 2 aft, accessible through deck hatches, with a rudder hung off of the stern.

    The proposed propulsion will be by pedals, cadence 60 BPM, spinning a large (10" ?) toothed belt pulley going down to a smaller (2.5" ?) pulley on a Mitrpak 1:2 right angle gearbox, for a total increase of about 1:8. From there a 1/2" stainless shaft will pass through a stuffing box on the forward post of a low profile "centerboard trunk" where it will connect to the main 1/2" stainless shaft with a universal joint. At the end of the shaft I want to use a small diameter prop (by forum standards), namely, a 12 x 10 Torqeedo prop, which will turn at 480 RPMs.

    When the prop is submerged the universal joint will be at zero deflection.

    I chose that prop because the prop and shaft will pass through a retractable strut which will allow me to pull the prop up into a well at the after end of the trunk to enable beaching, rowing in shallow water, and for inspection, cleaning and maintenance through the clear 1/4" polycarbonate quick release trunk cap. A big plus in not using a 16" or larger prop will be that the well, which will introduce drag, can be smaller, thereby producing less drag. The Torqeedo prop is somewhat weedless as well.

    The Torqeedo props have the following specifications, which I just got via a phone call to Torqeedo. They were very helpful. I told them about this forum and this thread specifically and suggested that people here might be interested in prop specs, so you might hear more from them in the future.

    The 1901 and the 1915 are both 3 bladed RH 12" X 10" props. Mary Jo also told me that they are velocity 8 and power 350. I don't know, but I expect that that means 8 meters per second (17.9 MPH) at 350 Watts. There must be some difference between the two, I expect that it's the hub to shaft joint.

    There is also a part number 1912 2 bladed RH of unknown diameter and pitch (probably the sames as the 1901 and the 1915), V 10 (22.3 MPH). P 350.

    I know I'm not capable of sustained 350 W. output, I may not be capable of 350 W. output even in a short sprint, although I'm reasonably fit, but that's just fine, I'm in no hurry.

    So Jeremy, and thank you for your help with posting images, can you tell me what sort of cruising speed/efficiency I can expect with the suggested drive train and hull? I would be barely content with 4 MPH, and thrilled with 6 MPH. If that is an unreasonable expectation can you advise as to what changes I should make? I'm not at all interested in making my own prop(s).

    Also, has anyone tried using a planetary gear in the drive train? It could be that considerably more RPM's will be necessary and planetary gears will do just that.

    And another question. Does anyone know which is the mechanically superior gearbox, the Mitrpak or the TEA transmissions box, which is available as 1:3?

    Thanks in advance, I'm on the edge of my seat.


    PS....Submarine Tom, it appears that you're nearby in Victoria, I'm over on Salt Spring. I spent some time in the US submarine service. Are you a submarine guy? There aren't many around.
  3. portacruise
    Joined: Jun 2009
    Posts: 1,208
    Likes: 72, Points: 48, Legacy Rep: 218
    Location: USA

    portacruise Senior Member


    Maybe this will help:

    It has most of your requirements as regards retractability, even from a well. The unit pictured is no longer made for sale, but Bob may have some left over. His location is in your general area.

    Somewhere in this forum there is mention of Torqueedo props not being that efficient with human power.

    Good luck.


  4. Gib Etheridge
    Joined: Nov 2012
    Posts: 28
    Likes: 1, Points: 0, Legacy Rep: 13
    Location: BC Canada

    Gib Etheridge Junior Member


    I tracked him down a while ago. He doesn't live around here anymore and sold the business to another person who is just sitting on it for the time being. I've spoken with that person and will get together with him as soon as possible, but I don't think anything will come of it.

    As far as the Torqeedo prop not being ideal goes, I can see where it would not be optimal for you racing guys, but I only want to know if i can expect 4-6 MPH, and I'm hoping someone (like Jeremy) who's an expert with Javaprop can give me a good estimate of what to expect.

    Thanks for your interest,

  5. Tom the rower
    Joined: Dec 2012
    Posts: 9
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Jacksonville, Fl

    Tom the rower Junior Member

    introduction and questions

    Hello, my name is Tom and I am about to build a pedal drive based on the designs of Rick Willoughby and Mike Lampi and Ian Cassell, which is to say a side mounted with a spring steel shaft and a APC prop. I have been reading this thread all this year, but am ready now. My very favorite boat is one owned by Clive Armitage in Maui, shown on youtube under Pedal Wa'a, which is a total weight of 68 lbs, on a huki hull with amas.

    His is a thru hull design with two gear boxes, I believe. The ones that I will base mine on will use the mitrpak T-102-m, but others have used a much less expensive gearbox made by advantex. I do like Clives pedal wa'a for the ease of all day pedalling using a 58 tooth ring to a 10 tooth sprocket.

    My questions are: the spring steel shaft. I have found sewer rod, up to 72 inches by 5/16 inch, but when I look at Rick's shown here

    his shaft looks much more flexible than a solid sewer rod and I would have that as well for shallow water and weed clearing. Does anyone know where in the US that I could obtain a flex spring steel shaft?

    My first boat that will put this on will not be as skinny as most other pedal boats, mine will be the 20 ft expedition rowboat that I just finished. So it is 175 lbs. Might that mean possibly apc 20x20 prop and perhaps a different set of chain rings?

    Thanks for any information you might provide.

  6. Submarine Tom

    Submarine Tom Previous Member

    I believe Rick uses spring steel rod.

    I can't remember what diameter, 5/16 perhaps...

    You could try contacting him on his website.
  7. Submarine Tom

    Submarine Tom Previous Member


    Yes, I'm in Victoria.

    My moniker came from my original posts here years ago when I was designing an electric manned torpedo for sport/fun.

    Think of it as a sub you wear.

    I've toured the VICTORIA but have never been down and at this point in their evolution, I don't think I would want to.

    Doubt I'll ever have the oportunity to make that descision though.

    Would you go down in one (meaning one of the four ever built)?

    A model airplane prop may be a better choice for your build but perhaps not in that diameter.

    Jeremy could better advise you on that.

    I used to work at the lifeboat station in Ganges.
  8. portacruise
    Joined: Jun 2009
    Posts: 1,208
    Likes: 72, Points: 48, Legacy Rep: 218
    Location: USA

    portacruise Senior Member


    Rick uses 8mm or 10mm spring steel which is very strong, for racing. Short piece as possible in his latest boat for increased torsional stiffness. He also custom built a CF shaft, but it was not stiff enough. Closest thing I have seen in the US is 6.3mm (1/4) electrician's extensions easily available:

    I believe this was used in Greg's sea challenge boat because the larger diameter was not available in North America...


  9. Gib Etheridge
    Joined: Nov 2012
    Posts: 28
    Likes: 1, Points: 0, Legacy Rep: 13
    Location: BC Canada

    Gib Etheridge Junior Member


    I was on the Sam Houston, SSBN 609, and the Sailfish, SS 572. The sailfish was diesel electric, most similar to the Victoria class of the two, the Sam Houston being a nuclear powered missile boat.

    I was below decks in the engine room of the Long Harbor ferry a while ago, and although comparatively speaking it was as roomy as a soccer field I felt a bit claustrophobic, something I never felt when I was 45 years younger, so no, I'm not interested in going submarining again. I survived some very scary situations during my enlistment, I still have dreams and the fact is I hate being scared. I will tour the boat someday though, but probably not soon. I make it a point to just stay here on the island.

    Now, having said that, I have all of the knowledge and skills to build a 1 or 2 man cold moulded over strip built diesel electric submarine, and I do fantasize about doing it from time to time. Maybe if I'm ever very wealthy, to pass the time.

    Are/were you in the Coast Guard?
  10. portacruise
    Joined: Jun 2009
    Posts: 1,208
    Likes: 72, Points: 48, Legacy Rep: 218
    Location: USA

    portacruise Senior Member


    Sorry about that tip, Bob was trying to sell his molds last I heard.

    Not a racer myself; my thinking was even a slight increase in prop efficiency pays off big, over long distances.

    My guess is that planetary gearboxes would have to be massive to take the load; there are even recent stories of mitre box failures.


  11. Submarine Tom

    Submarine Tom Previous Member

    The SAILFISH, well isn't that something.

    You're about the fifth retired submariner I've "met" and the sentiments all sound remarkably similar.

    Are you familiar with Cliff Redus's R-300?

    He's in Texas and must have $300 000 into his one man electric sub.

    Fly by wire, the works.

    Mine is a much simplier design although my wife often reminds me that the word submarine and simple don't belong in the same sentence!

    I left the CCG eight years ago after five years in Search and Rescue.

    I have a 60-GRT Commercial Towing certificate that I don't use anymore.

    How long have you been on Salt Spring?
  12. Scheny
    Joined: Feb 2012
    Posts: 72
    Likes: 5, Points: 0, Legacy Rep: 47
    Location: Vienna/Austria

    Scheny Junior Member

    Hello Gib!

    I have already done a lot of research about Torqeedo props. Your assumptions are not quite right. Their notation gives the optimal cruise speed in kilometers per hour ( (m/s)/3.6 ) and the corresponding shaft power in Watts.

    For your project, the only suitable prop is the "ultralight" (kayak) version. The other ones show about 30% power loss for human powered application, as they are designed for high power. Also it needs 1200 rpm for 10km/h.

    I don't know if you read all my postings, but I engineered a 3D-printable prop which is small, efficient and weed shedding. The outcome looks nearly equal to the Torqeedo prop. I found, that using a small prop with a big blade only lowers efficiency by about 2-3%, while making it weed shedding, robust and having hell of pale thrust.

    The power consumption is mainly dependent on the drag of the boat for a given rpm. So its crucial to have the right gearing to get a good balanced drive. I would not recommend to use something else then a 1:20 gear ratio, as the prop needs its 1200rpm. Nonetheless, the prop is optimized for driving 2 persons at 10km/h.

    If you are interested, you can try my prop design, which has the same dimensions, but:
    • 150W @ 3m/s (cruise)
    • 650W @ 5m/s (sprint)
    • 1:14 gearing

    The price for printing is just the same as for the Torqeedo. As I currently build my own boat and need other people to confirm my data, I would offer to provide you a free custom designed prop.

    Greetings, Andreas

    PS.: For your toothed belt, I recommend the "Strida" front pulley, which is readily available for a HTD 8M. It has 100 teeth and costs 150$ including even the pedals and the excenter shaft.
  13. Gib Etheridge
    Joined: Nov 2012
    Posts: 28
    Likes: 1, Points: 0, Legacy Rep: 13
    Location: BC Canada

    Gib Etheridge Junior Member


    Anything I built would be much simpler too. I'd like to see yours, is there a link?

    I've been on Salt Spring most of the time since 1972 when I stumbled on it by accident.
  14. Submarine Tom

    Submarine Tom Previous Member

    Mine isn't complete. I've run into some health issues, funding hurdles and parental responsibilities...

    What is moving ahead, however, is my pedal powered hydrofoil.

    I'm in the midst of sorting through the electronic micro processor with a group of radio control enthusiasts.

    It's an interesting evolution.

    I'm considering fly by wire that would over ride complete automation of the control surfaces in order to get it to balance on one strut while foil born.

    It's very exciting.

    Personal message me your email and we can coorespond more on that if you like.

    Click on my moniker (name) and you'll see the PM option.

    72! You sound more like a draft dodger than a submariner! :) Don't worry, we like both up here as I'm sure you've already learned.

  15. Dennis A
    Joined: Aug 2009
    Posts: 40
    Likes: 2, Points: 0, Legacy Rep: 47
    Location: Amersham bucks uk

    Dennis A Junior Member

    Pedal Powered Hydrofoil

    Hi Tom
    Your foil project some good but do you really need an adjustable front foil or is this something that has just followed on from the previous models.
    The Flyak uses a fixed front foil and that seems to be very stable.

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