Pedal Powered Boats

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

  1. Colin McDonald
    Joined: Apr 2010
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    Location: USA

    Colin McDonald Junior Member

    Hello Everyone,

    I need some opinions - - Who out there has converted a Hobie Cat or other similar sailboat catamaran to a Pedal Powered Boat??? I know Turnip has and OldNick was trying. anyone else?? How big are your hulls?

    Basically I have the opportunity to go with either a Hobie 14 (14 foot long, 7.5 wide) or a Hobie 3.5 (which is 11 foot long, 6 foot wide)... Any suggestions? Im concerned a litte with having too much weight on the 11 footer and being too big/slow on the 14 footer.

    Looking to have some equipment and maybe a tent on there...

    Thanks!!!!

    Colin
     
  2. spidennis
    Joined: Feb 2007
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    Location: south padre island, texas

    spidennis Chief Sawdust Sweeper

    Colin,
    I got plans to put peddle power on a pair of prindle 16 hulls before I try different hulls of some sort. It'll mostly be a sailboat, but needs peddle power to get up channels, rivers, and whatnot. It'll have a biplane rig with kite power. Times are tough right now so all I can do is research this project and learn how to kite board (I've been windsurfing for years).
     
  3. Tiny Turnip
    Joined: Mar 2008
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    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    Hi Colin
    To a point, longer is faster. My dart conversion is 18 feet long. Windage and Drag due to wetter surface are probably the limiting factors for the low power available from a human engine. Go with the longer hulls.
     
  4. spidennis
    Joined: Feb 2007
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    Location: south padre island, texas

    spidennis Chief Sawdust Sweeper

    what kind of speed and duration can you get with your rig?
    and is one person enough to move this fairly well?
     

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  5. OldNick
    Joined: Dec 2009
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    Location: Perth, Western Australia

    OldNick Junior Member

    As you said Colin still trying! :)

    I have been dong some calculations with Freeship, to see where it takes me. _If_ you use the 14' model for the same load and are not tempted to add more :rolleyes: then it will possibly go a tiny bit faster. The longer hull is offset by the fact that _if_ the hull shapes are pretty much the same, you sit higher and the wetted area stays about the same. Top hull speed would be higher, but you are not after that. However it may help in a current, as long as you can keep the power up to the pedals.

    Because you have a cat, you have to halve the power that is available to push each hull. Luckily this does not halve your speed because the power/speed is not a straight line: it gets easier and easier to push as you get slower and slower. You lose somewhere between 23-28% AFAICS.

    I reckon that with moderate fitness, and not pushing (I used Rick's figure of 100 watts), you should get about 4-4.5 knots with an all-up load of around 180Kg. That assumes that the cat can carry that much. A later model, which has a rounder bilge and more volume, can carry 227kilo. 14' hobies and even 12' hobies can carry two adults, so over 150kg. You need to find what the capacities are.

    4 kt is a good walking pace. 4.4 mph. 14 minutes per mile.

    Remember that weight includes the boat. Hulls and beams probably 35-40Kg???? Say 40. So you have 140Kg. You weight say 85 (or whatever! :))so 55kg of gear. (or whatever! :)).

    If you can boil and drink the river water, so much the better. But I hear a lot of the big rivers are pretty chemical these days.:(

    All up, as people have said go for the larger. You are not in a hurry, and the speed is so close to the same as to not count, AFAICS. Like about .1-.2 knots.
     
  6. Clemens
    Joined: Jan 2010
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    Location: France

    Clemens Junior Member

    Hello Colin,
    I agree with Tiny Turnip - I'd prefer the 14 feet Hobie as well.
    I plan to enlarge the platform of my seacycle twin in order to install a bigger tent on it. I bought one of Quechua's "2 seconds air" for this reason. I'll strap it down to minimize windage while cruising whenever there will be too much wind.
    Best greetings from France
    Clemens Winter
     
  7. Tiny Turnip
    Joined: Mar 2008
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    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    Hi Spindennis
    I haven't done any controlled speed trials, and niggling issues with the drive set up have meant I haven't had a full out sprint that I have been happy with yet. However despite the drive issues, two up we have had very nearly 6 knots and Rick has estimated that 8 knots plus as a sprint should be realistic.

    Last summer we completed a 15 mile circumnavigation of the isle of Gigha, 2up. It took 4 hours with a couple short stops. what really pleased me was that this was half the time taken by the island's 8 man gig the day before.
    This pace is doable all day without getting out of breath.
    It is easy to sustain the same speed with one engine, but does require notably greater effort, that wouldn't be sustainable for someone as unfit as me.
     
  8. Colin McDonald
    Joined: Apr 2010
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    Location: USA

    Colin McDonald Junior Member

    Really great info, guys!! - - Truly appreciated!

    The thing is, I am still leaning towards the 11 footer. The reason being I can carry it on top of my car - Transportability. I have been doing a lot of thinking about it...

    I would love to have the 14 foot hulls based on your suggestions, believe me. But I don't have any space to put a trailer if I had to have one. It seems as though you guys are mostly into the 2 drive system for two people, which is great, but my boat is being built for solo adventures, and ease of transport is (I think) important since I live in the middle of Ohio and would have to truck the boat to the river/lake everytime I want to go boating.

    If, according to OldNick's amazingly helpful calculations, the 11 footer should act similarly to the 14 (basically-ish), then it seems I would want to go for the 14 because it would offer more room, and possibly a little bit more speed. And I want to go with the 11 footer because it offers ease of transport.

    Heres my question:

    Do you guys think that using an 11 footer would be unreasonable? dangerous? Really wouldn't work?

    I am just wondering if it is more of a "Dont use the 11 because its unsafe and wont work" or more of a "Dont use the 11 because you would get more room and possibly more speed with the 14"

    Thanks, Guys!!!

    (attached is an 11 footer on top of a 14)
     

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  9. Tiny Turnip
    Joined: Mar 2008
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    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    Hi Colin
    Car toppability is a totally reasonable parameter, as is portability.
    Perfectly reasonable not to consider speed an important design parameter as well!

    I would say that safety is entirely dependant on where you intend to take the boat. There are many other factors to safety that are probably more significant than the difference between 11 and 14 feet.

    The smaller displacement of the 11footer is likely to have a significant impact on the amount of gear you can carry. As displacement is a cubic function, the displacement of the 14 footer, if the hulls are a similar shape, may be of the order of 2 x the displacement of the 11 footer.
     
  10. Clemens
    Joined: Jan 2010
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    Location: France

    Clemens Junior Member

    Hi Colin,
    I agree with Tiny Turnip. Transportability is an important factor. I also transport the seacycle on the car's roof rack. The slightly inferior hull speed (4.6 knots) of the 11 foot cat would not bother me either. What size is the trampoline? Can you limit your gear to less than 100 pounds?
    Do you intend to sleep on the boat?
    Best greetings Clem
     
  11. OldNick
    Joined: Dec 2009
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    Location: Perth, Western Australia

    OldNick Junior Member

    That photo is interesting. All this is surmise. The hull forms look pretty close to the same, just that one is shorter. So your loss of capacity may not be as bad as a full cubic loss that TT mentioned. Maybe 9-10/14ths, rather than the half that a full cubic loss would mean.

    Safety. People go out in amazing conditions in kayaks, and are OK. You will need to develop skills for bad conditions, such as windy, or big wakes. Find a place where you can encounter that sort of stuff, not far from shore.There will not be much difference in the safety aspects of the 11 and the 14 as long as you do not overload.

    I have sailed an 11' moth in 25 kt winds on a 2.5-3km reach of water, with hundreds of pleasure craft helping kick up 3-4' chop. Was it safe? No. But I kept my wits about me and I am still here. It was also about the most fun I have ever had sitting up.:cool:
    While a sailhas a steadying influence on a boat, it also has enormous power and these boats are built to take that and to survive moving at sometimes well over 10kt. So just you, pedalling, will be able to handle pretty rough stuff, with the right skills.Remember that a surfcat cannot sink unless severely damaged ( or you leave the bungs out... DAMHIKT). You should learn deep water retrieval from capsize (you can probably find a lot of info about righting a cat on the web), even if it involves inflating a bag with air etc. But even if you fail, you can sit on an upside-down cat and you will end up somewhere, if you are on a river.

    I really wish you well in this. It sounds as if you are looking forward to it.

    Just to throw a spanner in the works, re transport. These cats can be dismantled. Normally that is too long an exercise for a day out, but if you are driving a long way and going to be doing more than day trips, it becomes less of an issue. I do see that the tramp is quite a bit wider though on the 14'. Nick
     
  12. Tiny Turnip
    Joined: Mar 2008
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    Location: Huddersfield, UK

    Tiny Turnip Senior Member

    I think you're right, OldNick - the hulls do look to be the same section, so the relationship to displacement will be nearer linear.

    I've had my boat Fangle out in a F6, in sheltered coastal waters, 6ft waves. It was great fun, but on the limit. As you'd expect, the windage was the limiting factor in control, and she did feel as if she wanted to broach surfing down the waves. I expect the hobies will handle better than the dart hulls in waves though.
     
  13. OldNick
    Joined: Dec 2009
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    Location: Perth, Western Australia

    OldNick Junior Member

    Well I don't know about that. I have sailed several types of small cat, but not hobies. I don't know what their extreme rocker will do to wave response when they have slow speed. Their asymmetrical triangle shape would make them track (which can be good OR bad in a following sea) but the banana would take that back again.

    They are a whole lot less boat to handle than the Dart at 18', so that's in their favour, I reckon.

    I have watched a couple of guys surf a 16' Hobie onto a beach in a good 20kt afternoon sea breeze. The boat handled the waves no problem, but of course it had enormous speed and was actually beating the waves then surfing down them. The skipper was very clever. He just waited until the surf was about to break and stayed with that wave right up onto the beach. It really was something to watch.

    But that's not 4-5mph pedal power :). But really, even the 11' should be able to handle river chop, and big wakes are going to be rolling, unless you are right next to the bigger boat, or in the shallows. They are not really a two-adult boat, but you can pack a lot into 20-30Kg of gear.

    I reckon actually that if the dart, being pedalled only, in those conditions, did not broach, then it did very well....or you guys did.;)
     
  14. OldNick
    Joined: Dec 2009
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    Location: Perth, Western Australia

    OldNick Junior Member

    I know I am all talk and no action ATM, but I am so envious of you guys who have shots of your boats to post (and in Rick's case "boats" is the operative word! :)). I have a new house to get together, and a workshop to set up, and I do not want t6he damn project to simply sit there taking up space.

    It will happen....:rolleyes: I love talking here because I can impart what I am able to and it keeps the idea bright and fresh in my mind.\

    Nick
     

  15. Clemens
    Joined: Jan 2010
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    Location: France

    Clemens Junior Member

    Hello Colin,
    I don't think there is a difference between the two models as far as safety is concerned. One experience I want to share: My seacycle set-up with the small tent on the platform is hard to steer when there is much wind. The standard rudder is too small and the tent is placed too far aft. Beyond 4 Beaufort, the boat tends to turn into the wind like a vane. That's why I'll place the new and bigger platform further up front, in addition I'll strap down the tent in windy conditions to minimize windage. This way I won't risk to lose any gear, since everything is well wrapped in the tent nevertheless. I can recommend a small bimini top as protection against heat, sunburn and rain for multi day excursions.
    Best greetings
    Clem
     
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