Dynamic stability system

Discussion in 'Boat Design' started by willfox, Oct 1, 2011.

  1. willfox
    Joined: Oct 2008
    Posts: 79
    Likes: 1, Points: 8, Legacy Rep: 22
    Location: southampton

    willfox Junior Member

    I was recently thinking about how this system works?

    Is the curved foil projected into the water on the leward side of the boat producing lift normal to the top surface of the foil. This then adds righting moment to the vessel allowing sail area to be held for longer. It is not the intention for it to produce lift in the plane of the keel therefore adding Keel side force.

    I find this very interesting and was thinking about seeing the effects if I added this to my own primative VPP excel spreadsheet. Assuming the assumption I have made about the application of the system. How would you tackle this problem do you think?

    I assume any drag that the added foil creates would be added to the resistance of the vessel using the ITTC calculations as per rudder, hull and fin. The sails would then need to compenste for this by being bigger or more efficient to create more drive.

    The foil will obviously increase the righting moment but how would you tackle this increase? Would you simply add the lift created multiplied by a lever? If so, where eould you take this lever from? Would this be from the CL of the vessel or do you think it should be the distance from the center of lift generation of the foil to the perpendicular intersection of BM?

    Once this increase has been found giving the new RM, it will then obviously be an iterative process seeing the optimum extent of foil being used in different conditions.

    Has anyone tried writing this spread sheet?
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