Pedal Power or Oar Power - which is more efficient?

Discussion in 'Boat Design' started by SailorDon, Jun 6, 2015.

  1. portacruise
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    portacruise Senior Member

    If timing chains inside IC engines and CVT chains in transmissions count, there are a large number chain driven autos....

    PC
     
  2. Skyak
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    Skyak Senior Member

    CVT "chains" are actually more like V belts that run in compression.

    To the question of the OP, the prop is a bit draggy but there is a huge difference in kinematic efficiency of pedaling compared to rowing. The big thing nobody has mentioned is the 'efficiency' of direct load and the loss of muscles straining but doing no work. Compare walking up a stairmaster -it will get your heart rate going but it is sustainable for long periods and the power output is your weight*vertical velocity. Now take a 20 to 30lb dumbbell and hold it out 2 feet from your body -this does no work but it takes more effort and is less sustainable. The stairs are analogous to the direct force work done peddling, and the dumbbell is analogous to the waist intrinsic to rowing where the force runs from the ball of your feet, through your legs, your back, your shoulders, your arms and finally your hands. Of all those muscles activated and controlled, few are doing useful work. This is how peddle boats can run at impressive speeds even with inexperienced pilots and despite their obvious losses.

    Now, even though you could peddle maybe a knot faster it seems to me the right boat for you is the one you have -because the whole point of the exercise is EXERCISE. All the muscle activation through your body is exactly what you need, and you are pretty good at it! Even though much of your muscle activation does not contribute to your speed, it does count for isometric exercise.
     
  3. HollaStern
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    HollaStern Junior Member

    what about a hybrid system with a prop or mirage drive run off the movement of the seat while you are rowing? Maybe its too complicated...
     
  4. Markmysite
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    Markmysite Junior Member

    Kayaks

    I have 4 Hobie Mirage kayaks and they all have the pedals. They work like a penguins wings to create lift and propel the boat through the water. We have lined up 2 of them and the foot pedals and much more efficient. You are using much larger muscles in your legs and you can pedal/push for long distances even if you aren't in shape.

    Here's a Youtube video that shows a pedal kayak against Olympic rowers. It takes two large professional rowers to beat the one couch potato on the pedal kayak. Not sure if the efficiency is the same with pedals on a rowing skiff (beautiful boat by the way).... But they work very well on a kayak!

    https://m.youtube.com/watch?v=D0rvFdLdplA
     
  5. SailorDon
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    SailorDon Senior Member

    Seems like you would have to design a bicycle powered by a "sliding seat" first.
    Bicycle pedals and cranks seem to be much more common drive mechanisms. :D

    But perhaps your sliding seat driven propeller concept would be more efficient. You can design and build one, test it out and prove the concept. If you think it is a winner, you might want to patent it before giving away the design concept. ;)
     
  6. SailorDon
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    SailorDon Senior Member

    I have not had the opportunity to try a Hobie Mirage kayak. I would like to give one a "test drive". I tried a few kayaks at Austin Kayak Demo Days in Conroe, TX, but the Mirage drives were not on demo. The dealer was concerned about damage to the flippers when leaving or returning to the shoreline.

    I have seen one Mirage Pedal powered kayak at the Dallas area boat show on Lake Ray Hubbard. No chance for me to take it for a "test drive", but the guy who was pedaling around seemed to be able to hold a decent speed for a few minutes, after which he came back and tied it up to the dock. Not exactly an on-the-water display of endurance.

    So the question remains, is there a pedal powered skiff (or kayak) that I can pedal for 2 hours at 4.5 mph constantly? (no wind, smooth water).

    As a benchmark, a few days ago I rowed my Thames Rowing Skiff for 5 miles in 1 hour and 11 minutes, non-stop.
    [​IMG]

    This rowing performance chart is prepared from data recorded on a Gamin Montana 650 GPS.
     
  7. Markmysite
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    Markmysite Junior Member

    Pretty impressive distance for oar rowing! I think you could easily achieve that with a Mirage drive. I would go with the Revolution model if you want speed. I have 2 Outback ones (wider) and 2 smaller Mirage Sport models for my kids. If you can do that with oars you can do it with pedals. You would need to build up your leg endurance, but I think it could be done. I can pedal my Outbacks 4-5 mph for pretty far distances. They have Turbo ones that give you about 10% more speed. The Revolution models can probably do closer to-6 mph consistently. I think the thing you would lose is the gliding you get on the skiff. It depends on what you want... speed for the sake of speed or the type of workout you are getting.

    Get on the Hobie forums and i bet you could find someone who would let you test drive theirs. Or try Craigslist and look for a used one. I test drove each of ours first. You could try calling dealers and see if they allow demos... They do around here.

    I have a sail kit that i use when fishing to get to the spots that are farther away. They make for a fun outing and it would be a good variance to work out your legs as well.
     
  8. portacruise
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    portacruise Senior Member

    The Cadence will give you at least the speed you desire, and you can pedal harder if you are not getting enough aerobic workout. But as previously mentioned, pedal power may not do much for other muscles groups than legs, compared to rowing.

    Rick W. commented on the Mirage drive vs. props on the Pedal powered boats forum and favored props for efficiency/speed.

    The Mirage promotional emphasizes that it can excel in the bollard pull. But a pedal system with a very large prop can sustain/exceed that pull over a longer period of time. Pull doesn't translate into efficiency or high sustainable speed when compared to props or even rowing. Analogy- maybe like comparing a 2000HP tug boat vs. a 2000HP racing boat? I love the Mirage concept for it's cleverness and utility. Hundreds of thousands have sold, but I don't expect them to be competitive in the endurance speed category.

    Just my humble observations, other's may differ.

    PC
     
  9. rwatson
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    rwatson Senior Member

    Here is a first hand bit of advice from Rick Willoughby, that I saw in action when he was down at the same lake I was - you don't need a support strut for the prop shaft.

    He had his handmade prop attached the the end of a 1.5 metre stainless rod - and when power was applied - it straightened up and aligned itself perfectly. I was impressed.

    The prop itself was barely larger than some of the large model aeroplane props. Like all human powered devices - cutting every ounce of weight is a priority.

    I suspect that a pedal powered boat can be flimsier than a rowboat, because you dont have to have the strong rowing rig.
     
  10. Markmysite
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    Markmysite Junior Member

    That's a good point and I wonder how the Native Watercraft Propel ones do for endurance vs the Mirage drive. I've never seen one of them but I like the idea of instant reverse for fishing uses. This guy seems to be cruising well in it but I've never seen it in use. I suspect that the drag on it or the Hobie would be a lot compared to a skiff with rowing oars.

    https://m.youtube.com/watch?v=R83c_gKTGY4
     
  11. SailorDon
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    SailorDon Senior Member

    Years ago, someone posting as "Guest625101138" started a thread on this forum about pedal powered boats, and included this graph of data he obtained from his trial of the Cadence pedal powered boat.
    I think it is the same design that you refer to.
    [​IMG]

    Assuming the red graph "HR" is heart rate, the maximum speed heart rates (160 BPM) are significantly over my 100% exercise maximum heart rate for my age group as specified by the American Heart Association (yes, I am that old).
    There are only 2 time intervals where a speed of 5 mph (8 kph) is maintained for 10 minutes. Most of the data appears to be "flash in the pan" bursts of speed followed by 20 minutes of 2 mph with the heart rate at 110 BPM. That leads me to believe that these are explosive, quick bursts of pedaling power to achieve maximum speed.

    It is difficult to determine the potential of the Cadence with respect to the claim of cruising at 5 mph "all day long". There seems to be lack of data, perhaps because nobody cruises a Cadence non-stop for 5 miles.

    I would sure like a "test drive" in a Cadence, but my guess is that the closest one to me would be over 1,000 miles away. :(

    The Cadence might be the most efficient pedal powered boat, but I'm not convinced it is more efficient than a performance rowing skiff.
     
  12. portacruise
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    portacruise Senior Member


    The start/stop graph above is not about highest sustained speed at cruising, and may not apply to a more recent updated model- see adventures of Greg post above for something possibly more applicable.

    The Cadence is NOT close to being the most efficient pedal boat- per post on prop size above. It may be the most efficient one of very few that can be purchased off the rack.
    Mike Lampi sometimes posts to this forum and has raced his Cadence against kayaks for years in Washington state. You can probably reach him from his blog for a free test. Here's some Q&A supporting sustained speeds:
    http://lampi.us/mike/cadfaq.htm

    Vacation travel has been the best time for me to test pedal boats of various brands at waterfront rental places by working in slight detours from my itinerary (as most will be far, far away).

    PC
     
  13. SailorDon
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    SailorDon Senior Member

    I searched for "adventures of Greg" and came up empty. :(

    I viewed the "lampi.us" link and there was no data on cruising speed....just talk.

    If there is anyone that has a Cadence pedal boat within 200 miles of Houston, Texas that I could take for a "test drive", that is about my travel distance limit for testing pedal boats, rowboats, or kayaks.

    I have reviewed the comments and videos that have been posted on bollard pull and tug of war of pedal boat vs. kayak. It is relatively meaningless in terms of cruising performance since the benefit of the coast or recovery stroke, for oar or paddle, is completely lost while the pedal power provides constant pull even though it is less than the pull of the power stroke.

    My reason for starting this thread was to determine if my quest for a performance upgrade (from my Thames Rowing Skiff) for a human powered vessel should be of the kayak, rowing skiff, or pedal boat.
    From the data presented, the rowing skiff concept seems to be the most efficient for cruising. My benchmark (Thames Rowing Skiff) is based on a 200 year old design and there are several improvements of the rowing skiff design currently on the market, like the Heritage 18 from Little River Marine.

    The reason for investigating pedal power is that I don't want to be missing something that converts muscle power into moving your boat through the water more efficiently. And still be within the scope of a recreational vessel (i.e. no racing sculls). The ability to carry cargo and/or passenger is required for my application.
     
  14. daiquiri
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    daiquiri Engineering and Design

    Don, I think it could be an interesting scientific research, the results of which would be valuable for both amateurs and part of the boating industry involved in the construction and distribution of human-powered vessels. Perhaps your local university might be interested in getting involved.
    They could provide a well-trained crew and measurement equipment for the tests, and perhaps even build two similar boats for an equal comparison.
     

  15. SailorDon
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    SailorDon Senior Member

    I wasn't looking for a project on oar vs. pedal efficiency, just an answer.
    Or perhaps some cruising data on oar vs. pedal power.
    I posted my inquiry to this website in hopes that someone had already done the design, research, building and testing.

    Incidentally, 1/2 the work is done. For oar performance, I've got over 2,000 miles of cruising data on my Thames Rowing Skiff performance.

    For pedal driven, I find "bursts of speed" for data and subjective statements like you can cruise all day long at 5 to 6 mph.
    It might be different in pedal boats, but it takes more than twice as much energy to go from 5 mph to 6 mph in my Thames rowing skiff, so I get suspicious about statements like that.
    Show me the data! :D
     
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