Solar Model Boat

Discussion in 'Boat Design' started by Dill, May 7, 2007.

  1. Dill
    Joined: May 2007
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    Location: Perth, Australia

    Dill New Member

    My son has a school project of designing a solar powered model boat that has a max 350 sq cm solar panel. He wants to design it for speed but has not been able to determine what hull design would be best or the type of propellor. We have checked out most solar sites but there is not a lot of information around. Can anybody help??
  2. marshmat
    Joined: Apr 2005
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    Location: Ontario

    marshmat Senior Member

    A 350 cm^2 solar panel on a sunny day receives approximately 35 watts of sunlight (average is 1000 W/m^2). A typical commercial panel of 15% efficiency would thus produce 5.25 W; a higher-grade silicon cell like a Sunpower A300 might get up to 7.4 W of actual electricity. That's all you'll have to work with, so the task is to make the most of that power.
    The boat obviously won't be able to plane on that little power. So it'd be best to try to optimize it for displacement mode. Wave drag will probably be a big problem if you try to get it going fast; the solution is to make the hull as long and as thin as possible. But it also has to be lightweight, and you want it to be stable. Long, thin, light, stable and enough deck space for a solar array- sounds like a catamaran to me.
    Now the question becomes, how much work does your son want to put into the design. The simple route, good for up to around grade 9, is to do some sketches, then build. If it's a high school project and he likes the idea of learning some computer design methods, I might suggest the (free) hull resistance analysis software Michlet in "godzilla" optimization mode, it's tricky to learn and has a cumbersome interface, but is actually a remarkably elegant program that will almost certainly steer you towards a mathematically ideal solution to your design problem. Freeship/Delftship, (free from ) is a hull modeller that beginners find very intuitive. If you were to specify some shape and performance parameters (length, beam of individual hulls, weight, target speed, etc) I'd be happy to generate some "godzilla" optimizations for you, PM or email me on here if you're interested.
    But I think your easiest solution would be pencil-and-paper. Look at a sea kayak hull, and try to duplicate that shape in as narrow a form as you can while still having enough volume to support the boat's weight.
    For power, there are small, integrated electric drivetrains in several configurations available stock from model shops. They'll be somewhat more efficient than gluing a propeller onto a Radio Shack hobby motor, albeit also more expensive.
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