Pedal Powered Boat for the Baltic Sea / Coastline

Discussion in 'Boat Design' started by KalleA, Apr 30, 2009.

  1. KalleA
    Joined: Mar 2009
    Posts: 46
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Germany

    KalleA Junior Member

    Hello,

    having followed Rick W's threads on pedal/prop boats ("PPB") with great interest, I am beginning to seriously consider building a pedalboat myself. It would be an excercise and touring boat, to be mainly deployed along the Baltic coastline. I want the lightest and most efficient boat possible within the constraints of being able to safely handle the somtimes rough waters of the Baltic Sea. In essence, it should have the functionality of my sea kayak, but a more efficient and leg driven propulsion with electro/hybrid retrofit potential.

    In all, the criteria and initial thoughts are:

    1. Seaworhty enough for the Baltic coastline

    2. Size. Around 8 m length (transport is a secondary concern, if any, but it should have decent maneuverability for the smaller rivers and waterways I would also pedal on)

    3. Live Load. I weigh around 100 kg at 2 m height, plus say 10 kg for food/drink/eqpt.

    4. Fit-out. Nothing beyond the seat/pedal/prop assembly. Perhaps I will need a bilge pump?

    5. Hybrid. I would want to be able to retro-fit an electric motor at a later stage.

    6. Driveline. Probably a normal crank/sprocket/chain/90 deg gears with a flexible propshaft. It should be possible to easily lift the prop out of the water for clearance/beaching. I am intrigued by pendular swing arms w roller cams as an alternative to the crank setup, but it's probably better keep it simple at this stage.

    7. Superstructure. It should be an open boat, but I think with some form of fairing and/or wave deflection, given the conditions on the Baltic. Don't know how wet a performance optimised boat might get, but a cockpit with a spraycover secured to the cockpit rim, like on a kayak, might be an acceptable option. (Note: this is partly why the pendulum swing arms could be interesting, as they would allow for a lower superstructure than a crank/pedal setup.)

    8. Construction. The boat should be as light as possible, and carbon over foam core would be OK w me, if it makes sense. Clearly, the best and cheapest weight reduction would come from lowering my CBD (Cheese Burgers/Day) intake...

    9. Displacement. I'm guessing the boat w. outriggers incl. seat/driveline could weigh in below 30 kg + 110 kg live load = approx 140 kg.

    10. Hull. This is one area (of many) where I am reasonably clueless, and would be grateful for input. From what I pick up here, I gather a long and narrow (wide enough to fit my bum inside) stabilised monohull should be the way to go.

    What are the relevant considerations for the above conditions, and how might such a hull look?

    Cheers
     
  2. Guest625101138

    Guest625101138 Previous Member

    A key input is the power you are able to develop or would reasonably achieve with some training on the boat.

    If you do not have an idea of your power level then head off to a gym and find a recumbent cycling machine that has adjustable load and a power meter. Most reasonable ones have this but you need to know how to adjust it to get the data. If there are three machines then try all three to see that they give similar results ie the power indicated matches the effort. Find the load setting that feels easy and spin a bit faster than loafing along. This is usually around 70rpm.

    You need to cycle for about 1 hour and see what is comfortable after this time.

    If you have a road bike then you can get some idea from the speed you can sustain on flat ground.

    There are other methods that are quite accurate and involve finding a building with about 10 stories or more and doing a few trips up and down the stairs.

    The engine is a vital part of the design.

    If you already have a good idea on your power output then just advise accordingly.

    Rick W
     
  3. KalleA
    Joined: Mar 2009
    Posts: 46
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Germany

    KalleA Junior Member

    Many, many years and kgs ago, I used to be a cyclist. My VO2 max was around 80 ml/kg/minute. Present engine capacity is hardly worth testing, but I guess that, with a bit of training, somewhere in the 120 to 150 W range might be realistic for longer period sustained level.

    I've got my eyes on a nice recumbent trike for getting back into something resembling shape.
    http://www.hpvelotechnik.com/produkte/scorpionfs/index_d.html

    [​IMG]

    Cheers
     
    Last edited: Apr 30, 2009
  4. Tad
    Joined: Mar 2002
    Posts: 2,300
    Likes: 174, Points: 73, Legacy Rep: 2281
    Location: Flattop Islands

    Tad Boat Designer

  5. KalleA
    Joined: Mar 2009
    Posts: 46
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Germany

    KalleA Junior Member

    Yup, Blueskies is pretty. Hadn't seen her before:

    [​IMG]

    Too heavy, wide and comfort oriented for what I am looking for though. 250 pounds is heavy. My rowing boat only weighs around 30 kg:

    [​IMG]

    Noticed that Blueskies is a stitch-and-glue build. I've recently seen some very nice stitch-and-glue kayaks (glass/epoxy over spruce) that compared very well with carbon fibre kayaks of similar design and dimensions - the weight was very similar to my total surprise.

    Cheers
     
  6. Tad
    Joined: Mar 2002
    Posts: 2,300
    Likes: 174, Points: 73, Legacy Rep: 2281
    Location: Flattop Islands

    Tad Boat Designer

    I usually associate stitch and glue with plywood hull skins. Paul states that BlueSkies was built "canoe fashion, of strips over temporary molds, then glassed inside and out."
     
  7. KalleA
    Joined: Mar 2009
    Posts: 46
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Germany

    KalleA Junior Member

    My bad. I think everyone associates stitch-and-glue with plywood hull skins.

    That's what my dyslectic mind wanted to say: strip building!

    [​IMG]

    Cheers
     
  8. Guest625101138

    Guest625101138 Previous Member

    A 140kg displacement hull optimised for 6kts (3.1m/s) requires 114W on the hull or about 140W at the pedals. It has 7.7m LWL and 0.3m BWL.

    This would be a likely starting point. For ease of build you would go to single hard chine. This will make it narrower on the WL and shorter as well. Power will go up a fraction.

    I doubt that there would be value in making a hull wide enough to sit in. There is really no advantage if it has outriggers. If you intended to have a boat that could handle any conditions then you would go for a ballasted keel to give stability. There is merit then in going wider to lift the metacentric height and also sitting lower to reduce the CofG.

    Fairing around the seating position would make it more comfortable in a seaway. This could be made as a bolt-on module and include all the drive components as well as the outrigger mounts. The seat could be part of the fairing.

    Rick W
     
  9. KalleA
    Joined: Mar 2009
    Posts: 46
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Germany

    KalleA Junior Member

    1. Thanks for all the input.

    2. The idea of a bolt-on module as you outlined is very appealing.

    3. My initial thinking re the hull was that, given the Baltic waves, the lower COG from a lower seating position inside the hull would add some initial stability, with the outrigers for ultimate stability. A bit like a longer, possibly narrower, propeller driven sea kayak. (In a kayak, apart from hull shape, one uses body balance, paddle and ultimately eskimo rolling, neither of which is possible with a propeller boat.)

    I.e. something between this:

    [​IMG]

    and this:

    [​IMG]

    (Both pics from http://www.adventuresofgreg.com - an incredible source of information!)

    4. I understand that there will be a point, depending on the expected wave/weather conditions, where a keel becomes the preferred option to outriggers. At what sort of wave heights might that be?

    I have studied the wave data for the Baltic, and was surprised at the annual variances in mean significant wave height - from less than 0,5 m to over 1,2 m from one year to another, wave frequency is 3 - 4 s. Would one be right in assuming that such conditions, even 0,5 m wave heights, already favour the keel approach?

    Cheers
     
  10. Guest625101138

    Guest625101138 Previous Member

    Here is a first go of something that is quite easy to build in flat panel. The cockpit tops would need to be single side flat panel and then outside done after placing.

    This boat has a hull power of 120W at displacement of 145kg.

    I can operate in waves to about .6m but it gets uncomfortable because I get green water over the seat. OK if it is hot.

    Fairing would make waves more tolerable. The stability is a matter of having enough buoyancy in the outriggers up to about 1m waves. If you want to operate in an angry sea with bigger than 1m waves then you should really go for the deep keel.

    I have been out in 70kph wind but only with short fetch distance so waves only around 0.6m. Under these conditions my greatest concern is just getting blown over with wind picking me up as I crest a beam sea. Of course if they are gentle waves left over from some weather then they do not present too much problem.

    The higher you sit the more influence your body has on dynamic stability. Once you get a bit of speed up it is surprising how much roll you can induce by steering adjustment. George Tatum's Wavebike made use of this and was dynamically stabilised once under way. It had tiny outriggers that were spring deployed just before coming to rest. (see dragrace image)

    If you are likely to encounter 30+kph winds in open water some distance from shelter then a keel is probably a better option. It will not perform as well as the sit-on hull.

    Rick W
     

    Attached Files:

  11. KalleA
    Joined: Mar 2009
    Posts: 46
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Germany

    KalleA Junior Member

    Looks very nice, and quite buildable. What software do you use? Seems I will have to try and learn to use something like that.

    Wow! You are very precise...:D :D

    I think that what you have produced here will be a good starting point for my first pedal boat. Better get something on the water and gain some experience for potential future iterations.

    There seems to be a lot of practical building information on http://www.adventuresofgreg.com, so I'll give that a thorough read now.

    Thanks for all the help!

    Cheers
     
  12. Guest625101138

    Guest625101138 Previous Member

    One too many "m" s. I think of wave height in feet- so 2ft. Going to windward that is the height of wave that will keep coming over the deck with enough height to drench the seat. I usually slow down to allow the boat to pitch enough.

    I use Michlet/Godzilla to determine the optimum hull form and then load the resulting hull offsets into Delftship Pro for the rest of it. You can get a free version of Delftship that has most of the functions of the Pro version. The basic Pro version is low cost and I felt compelled to make my donation to the developers because I have had a lot of value from it.

    Greg is doing a good job of blogging his activities. He generally does good work. He has time to test ideas put to him. He made a mess of the the propeller he fabricated but he solved that by getting the next one milled and it was very nice. Actually it took the machine shop 4 goes and two were OK. Only one was near perfect. Actually it turned out better than my original design because it ended up thinner than design after polishing it. I actually compared it with my V11J prop on his boat.

    Rick W
     
  13. Guest625101138

    Guest625101138 Previous Member

    Regarding the wavebike - George used to ride it in the surf. He could get a good portion of the hull air borne when driving through waves. It had a monstrous rudder so small movements generated large steering force.

    Rick W
     
  14. KalleA
    Joined: Mar 2009
    Posts: 46
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: Germany

    KalleA Junior Member

    I've downloaded and installed Delftship now. Can't find any download links for Michlet/Godzilla though. Any tips as to where to find that?

    Cheers
     

  15. Guest625101138

    Guest625101138 Previous Member

    It is no longer being supported so was removed from the cyberiad site.

    Rick W
     
Loading...
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.