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Radical New Sailboat Concept: Twin-Masted Swing Sail

Discussion in 'Future Yachts; Concept Boats' started by YachtForums, Sep 23, 2009.

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  1. Radical New Concept: "Split Mast, Swing Sail"
    Three Sheets To The Wind!

    by Carl Camper​

    Lila Lou Design has created a radical and possibly revolutionary idea, a swing-sail system
    with side-by-side, matching masts and booms that split port & starboard, harnessing the power
    of the wind, as well as electrical power with vertical-axis wind turbines. This system effectively
    doubles the sail area, generating so much power that twin sub-surface foils and a sliding keel
    bulb are needed to keep it upright. Revolutionary isn't always ridiculous, right? Read on... ​

    According to Lila Lou Design; "We have developed 'Ankida' in a manner that we see is the natural progression for sailing yachts, the most fundamental aspect of which is the mast, rig and keel configuration, moving away from a traditional centre line mast arrangement in order to structurally integrate the entire set-up with the hull and superstructure, making all wind generated forces work homogeneously with the craft, thus maximizing the propulsion efficiency." Obviously, Ankida will rely heavily on an automated mechanical system, coupled with a sophisticated software package for weather, navigation and operation. It is intended to be a yacht could effectively sail itself.

    A "traditional" central mast structure concentrates & focuses vast stresses and strains on the yacht's deck and internal structure and does not distribute this tension in homogenous fashion, it also creates a structural/visual barrier along the very center of the boat, externally and internally. We developed Ankida's mast(s) to be light, flexible and integral to the entire yacht's design so that the forces generated are more uniformly distributed throughout the vessel. Most importantly, this mast system favors performance. It was from the mast design that the sail design became interesting...
  2. The sail layout and operation is designed to allow for the greatest surface area coverage and optimal positioning in relation to the wind direction and conditions. To compensate for the leverage created by it's massive sail area, the keel bulb position automatically adjusts left-to-right to optimize the centre of mass, thus gaining the best performance. The design relies heavily on the full automation of the mechanics of its operation. Harnessing free energy, several vertical axis, wind turbines are located between the two masts that supply power for onboard electrical systems, making Ankida a truly wind powered vessel.

    Each mast side has booms parallel to one another, which would not be effective if one were "shadowing" the other, therefore the booms are hinged and have the ability to swing (or slide) forward and backward. This is done by building the booms in two sections so they are able to split along their length. The internal half is stuctural and remains in contact with the mast. The external half is attached to the internal support via a series of electronically adjustable straps that hold the sail, allowing them to be offset from one another, optimising the sail area for the conditions. The straps can also be adjusted to further angle and/or bend the sails allowing the yacht to sail closer to the wind.
  3. When the boat is running downwind the booms split, hinging out 180 degree from each mast to offer the maximum downwind sail coverage. This is much like a conventional rig, however power is being generated unilaterally on both sides and from each mast. This also negates the normal rotational torque a conventional mast transfers to the hull with the full power of wind behind it. All of the energy in this configuration is channeled into making the boat go forward, much faster. Additional speed can be attained by deploying a spinnaker that engulfs wind passing between the two masts. Theoretically, a Venturi effect could be created by wind being accelerated between along the sails and releasing into the spinnaker. When not in use, the spinnaker is furled into a box just below the wind turbine at the top of the masts. The poles for setting it pivot automatically out of the forward mast, in this configuration, there is literally a wall of sail propelling the boat.
  4. When not under sail the booms rest facing aft with the sail automatically furling in line with the aft straight mast. Obviously it is also possible for Ankida to just be under one sail, therefore having a port side sail or a starboard sail, which offers great flexibility when pleasure cruising, i.e. not blocking the sun, etc. There is such flexibility in the sail arrangement that coupled with some sophisticated software, they could be configured in virtually any wind condition to offer maximum efficiency.
  5. The profile renderings suggest the sub-surface foils could offset parasitic drag with additional lift and leverage. And while the wind turbine located at the top of the masts looks as aerodynamic as a barn door, the power generated by two sails should compensate well. Not to mention the onboard power generated by the turbine! Lila Lou has put forward a radical and possibly revolutionary idea... one that is certain to split sailors like a football through the uprights! <end>
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