Design Testing and models

Discussion in 'Boat Design' started by Kessica, Oct 15, 2006.

  1. Kessica
    Joined: Oct 2006
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    Location: London UK

    Kessica Junior Member

    Some great ideas and comments here. Although building a model will delay my build, I think it would be a highly useful task, and will teach me more about the build aswell as making adjustments etc. Im not a stranger to model building having built a fully aerobatic helicopter from a kit, and also a BAE Hawk from balsa straight from plans (ducted) which although hasnt flown yet it looks good lol

    One thing I love about these forums is the fact that professionals also post and offer ideas and suggestions. Some of the them might not be practicable from the amaeturs point of view, however these spark off new ideas and thoughts. I am still a sponge and read everything with a very enthusiastic interest. I often wish I was a lot younger and could change my profession from software analyst/engineer to a something in the boating industry where I could get hands on experience.
     
  2. RANCHI OTTO
    Joined: Apr 2005
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    Location: TRIESTE (ITALY)

    RANCHI OTTO Naval Architect

    For > Tom 2857

    Never problems with the weapons plant because I follow a specification and sometimes I decide the configuration of the final boat according to his mission profile...

    For submerged propeller I put a marge in propeller revolutions, so doing the boat is able to bear an overload in displacement without problems for the engines...

    The position of the long. center of gravity at high speeds (over 40 knots) is not more so important, the resistance curves are very closed even with discrepancies in l.c.g. location.

    I have a lot of admiration for people that test small model to investigate the difference between hull shapes...

    Don't forget that I'm an "amateur" too and I have my enthusiams of the begin intact, I learn each day new things from people writting in this Forum.:p
     
  3. Crashimir
    Joined: Oct 2006
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    Location: Croatia

    Crashimir Junior Member

    Model testing

    Good point Tom.

    I try to scale everything. If it is a 1:10 scale model than speed is also 10 times scaled down. Power is then calculated by some boatbuilding program. I use Maxsurf at work and freeShip at home. FreeShip is particulary good for amateur boatbuilder since it is free, and in some cases works better than Maxsurf. Also i do preliminary hydrostatics in these programs. Since boats my company builds aren't some experimental craft, and we use standardised parts like propellers i found that standard model propellers work satisfactory. It is not so importand to know exact speed during manouvres. I tend to look at behaviour of a boat in general. Later a lot can be made by simply moving components like tanks to fine tune the design once it is built. So far it worked to me.
    This method is well suited for amateurs.

    Example of that can be seen on http://www.pt-boat.com
    the site is about scratchbuilding of a PT-boat from WWII but principles used in progres are the same.
     
  4. RANCHI OTTO
    Joined: Apr 2005
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    RANCHI OTTO Naval Architect

    "if it is a 1 : 10 scale model than speed is also 10 times scaled down".....sorry but it is not true....the speed is equal speed model x scale^0.5
     
  5. Willallison
    Joined: Oct 2001
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    Willallison Senior Member

    Sorry - but I still fail to see the point in building a model here.
    Kessica was only talking about making some changes to the boat's general arrangement. Apart form anything else, a model isn't the place to be trying to measure changes in trim etc from variations in weight distribution - you make those calculations based on your weights & moents calculations. You might then wish to see how they affect performance by building a model, but that's another story altogether
     
  6. Crashimir
    Joined: Oct 2006
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    Location: Croatia

    Crashimir Junior Member

    Model testing

    I apologize to RANCHI OTTO for lack of precision. I didn't mean 10 times literally. English is not my native language so sometimes when translating directly from croatian it can soud somewhat wierd orwrong. But thanks for correcting me.
     

  7. Verytricky
    Joined: Oct 2005
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    Verytricky Large Member

    Kessika,

    In Devon there is a company called BananaShark Racing. They build 5 foot models of boat designs. They are very very good at what they do. They also have some knowledge to help with the design. Tehy are helping me with my boat.

    Its about time us Londoners showed the coastal people some beutiful designs.....
     
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