Need Boart design advice / new user

Discussion in 'Boat Design' started by cekuhnen, May 15, 2008.

  1. cekuhnen
    Joined: May 2008
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    Location: USA Grand Rapids

    cekuhnen Junior Member

    Hi

    I am curious about different hull configurations.
    I am going to work on a project for a paddle
    man powered boat for a lake like environment
    and would like to know more about hull designs
    in terms of stability and maximum usage of
    administered man power through the bike like
    propulsion system.

    I tried to google hull design aspects but found
    no usable information similar to a basic introduction
    into boat design.

    Could anybody give me some advice for where to
    look?

    Thank

    Claas
     
  2. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    Lots to learn. The typical paddle boat seen on most ponds around here is very inefficient, meaning slow.
    A faster boat would be longer and either have a pair of slender and long (at least 14 ft) hulls, with the driver in between, or a single narrow hull up to 20 ft long.
    There are books that explain the whys and wherefores of hull designs, what shapes do what, and some basic formulas.
    The Nature of Boats by Dave Gerr is good. Another hint is to read what kayakers have to say about hulls. They discuss some fine points about hull shape such as the prismatic coefficient, speed potential of a given length, and why a shorter hull can win a race even though a longer hull is potentially faster.

    Alan
     
  3. cekuhnen
    Joined: May 2008
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    Location: USA Grand Rapids

    cekuhnen Junior Member

    I agree that this is a rather aggressive undertaking.

    However all we would like to design are boats for
    a lake scenario.

    The propulsion system is based on what you use with
    a bicycle for one or two humans to power man.

    Additional functions could be space for relaxing / swimming dock
    and others.

    I am not even sure of the hull shape will have such a significant impact
    on the speed because it is man powered anyway.

    I am just curious if you could give me a direction. It seems that there
    is hardly any thing on the internet for it.

    Claas
     
  4. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    "I am not even sure of the hull shape will have such a significant impact
    on the speed because it is man powered anyway."

    The opposite is true. The hull shape is much more important when it is man-powered.


    You are already on the best forum for designing an efficient hull--- and building it too. Be patient and ask specific questions.
    Regarding using the hull for other purposes like lounging, you'd better decide ahead of time whether you want a boat or a dock. A boat that's stable enough to swim and lounge on will move like a pig in the water, nevermind go in or out of the water without a winch.

    Alan
     
  5. cekuhnen
    Joined: May 2008
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    Location: USA Grand Rapids

    cekuhnen Junior Member

    Hi

    than you for the tip. The problem I have is that I do not posses the
    knowledge you have. You said that the hull is important when being
    man-powered - like a paddle boat.

    Those are possible application for our project:
    - movable swim/tanning platform
    - fishing boat
    - fitness alternative
    - lifesaving vessel
    - children’s play vehicle
    - and others

    My question is simply how has the hull to be for example:
    stability - lets say it is a boat which has more a function of a play area for kids, or tanning

    stability - for lets say it is actually more for rescue purpose

    stability - lets say when the boat is also easy accessible for diving meaning leaving and entering the boat without shaking it seriously

    speed - lets say the boat could also be equipped with a kite and making use of wind power in addition

    Does this help?
     
  6. dragonjbynight
    Joined: Apr 2008
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    Location: Indiana

    dragonjbynight Senior Member

    My suggestion, for what it is worth, is to slim down your list of uses, as each one has different aspects that would require different things. The main theme of your boat seems to be a platform type, as a paddle boat. As was suggested earlier, they are very slow and if you have spent time in them, take a lot of energy to get them anywhere, specially in rough water. A small trade of for stability, instead of speed. For a platform though, it would work for diving, swimming and so on, but unless your using it as a lifeguard platform, would not be the best boat for lifesaving, as speed becomes a factor.
     
  7. cekuhnen
    Joined: May 2008
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    Location: USA Grand Rapids

    cekuhnen Junior Member

    Where ever motor driven boats are present of course
    paddle boats would not make much sense for life saving.

    However in this case they are more thought as a platform.
    Probably much better for the lifeguard than risking the own
    life as well.

    But yes this is a problematic application - probably not even a good one.


    Maybe my question is too much common sense you for guys - I am
    totally new to boating. However what affects stability and speed.
    A wide boat seems to be stable for - how far does this influence speed?
    Read the more you have wet surface the more resistance - the slower it is.

    However I have no practical experience to back this up.

    To make the boat easy to maneuver and also as fast as possible with
    the given propulsion system how has the hull to be? Flat - deep - short - narrow ... ?

    I hope you see here that I have barely any starting point.
     
  8. tinhorn
    Joined: Jan 2008
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    Location: Massachusetts South Shore.

    tinhorn Senior Member

    It's been too long since we had a pedal-power thread!

    There are some cool links on these pages:
    http://www.recumbents.com/WISIL/hpb/boat.htm
    http://www.humanpoweredboats.com/index.htm

    I'm approaching the process from the opposite direction - I've already purchased a couple hulls and tooling for one of them. My challenge will be maximizing the efficiency of the existing design. This forum is a great place to learn.

    As Alan and Dragon have suggested, you may discover that you need a few different designs to meet all your needs. A one-man fitness boat may also make a decent kid's boat, but probably not a good fishing boat or swim/tan platform. Is yours a commercial enterprise, or are you building in the garage with hopes to market it when the design is worked out and proven? If this is a low-budget project, what would be the primary use of your first design?
     
  9. cekuhnen
    Joined: May 2008
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    Location: USA Grand Rapids

    cekuhnen Junior Member

    This is actually a student project.

    So this is not for a company.

    We also will only have 6 weeks - it is a summer school project.

    Different target needs will be evaluated - however when it comes
    to the actual boat hull design things might get more complicated
    because marine design is not a big part of our school.

    Based on the target needs than the appropriate hull configuration
    and added functionality should be explored.

    The boat design should meet requirements for 2 axis rotational molding
    process thus we will only do model mock-ups out of foam and cad models.
     

  10. alan white
    Joined: Mar 2007
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    Location: maine

    alan white Senior Member

    The nearest I can come to an answer to what hull type you might want would be a 12 ft punt with a 3 1/2 ft beam and a flat bottom. Slow to propel, but probably much faster than a standard paddle boat.
    If speed is desired at the cost of some stability, then a sit-down-in canoe 16 ft x 3 ft, with a slightly rounded bottom. Such boats already exist, of course, that also use pedal power.

    Alan
     
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