new design motor size assistance

Discussion in 'Boat Design' started by wayne nicol, Sep 6, 2022.

  1. wayne nicol
    Joined: Dec 2009
    Posts: 163
    Likes: 11, Points: 18, Legacy Rep: 34
    Location: Queen Charlotte islands, B.C.

    wayne nicol Senior Member

    Hi all, we are working on a new boat design, and we want to move up a step past the drawings stage. and we want to build a smaller hull mockup, design is for a 33' power boat.
    we are wanting to build maybe just a 10' hull mock up and test the performance of some of the unique features.
    is there a way to make a guesstimate of what size motor would be used on the mockup, maybe based on the designed in motor size of the bigger craft.
    i realize there are a lot of other variables, mass, bouyancy etc, but we just want to confirm a few things before moving up to a full size build.
    many thanks
     
  2. jehardiman
    Joined: Aug 2004
    Posts: 3,773
    Likes: 1,167, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    It's not the motor, it's the prop. If your "unique features" have anything to do with propulsive hydrodynamics it is better not to use a geosim model but just conduct basic research to flesh out some operating points in the theory.
     
    duluthboats likes this.
  3. wayne nicol
    Joined: Dec 2009
    Posts: 163
    Likes: 11, Points: 18, Legacy Rep: 34
    Location: Queen Charlotte islands, B.C.

    wayne nicol Senior Member

    thanks,
    the features are design features within the overall hull shape.
    we were looking at doing some tow tests with the local university with their NA program, and that's good and well as its free, however, we lose any rights to the design concepts as they are introduced into the teaching program.
    so were wanting to do some of our own simulation trials comparing at least 3 different hull shapes, one being the industry standard, as that one will be used as the control/benchmark.
    thanks
     
  4. jehardiman
    Joined: Aug 2004
    Posts: 3,773
    Likes: 1,167, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    Look at this thread, just be aware that some things don't scale well.

    L/B ratios the same for short and long hulls? https://www.boatdesign.net/threads/l-b-ratios-the-same-for-short-and-long-hulls.67070/#post-930525
     
  5. HJS
    Joined: Nov 2008
    Posts: 482
    Likes: 130, Points: 43, Legacy Rep: 288
    Location: 59 45 51 N 019 02 15 E

    HJS Member

    To obtain reasonably comparable results, a load cell should be placed so that the propeller pressure can be measured. Anything else can lead to incorrect conclusions.
    JS
     
  6. tpenfield
    Joined: Dec 2016
    Posts: 281
    Likes: 30, Points: 28, Legacy Rep: 10
    Location: Cape Cod, MA

    tpenfield Senior Member

    Does the university have any guidance on scaling down a full-sized hull for testing purposes (without compromising your Intellectual Property rights)? I assume the 10' model will be too big for most test tanks. Is it better to use a smaller scale model and a test tank?
     
  7. messabout
    Joined: Jan 2006
    Posts: 3,368
    Likes: 511, Points: 113, Legacy Rep: 1279
    Location: Lakeland Fl USA

    messabout Senior Member

    Have you explored the patent office for prior art? People have been "improving" boats since before Archimedes.
     

  8. gonzo
    Joined: Aug 2002
    Posts: 16,803
    Likes: 1,721, Points: 123, Legacy Rep: 2031
    Location: Milwaukee, WI

    gonzo Senior Member

    You can tow the model with another boat and make a chart of resistance at different speeds. That will give a fairly accurate estimate of power needed.
     
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.