Optimizing Aerodynamics: the Bieker Moth

    The recent NZ Moth Class Winter Sprints held on 25th- 26th July showed just what these “flying yachts” are capable of with intensely fought out battles between the 17 strong fleet of boats.

    Sailing his Bieker Moth, Olympic medallist Sam Meech sailed smart and fast to take out the first of the Moth events this year.

    The Bieker Moth itself is proving to be a speed machine, where recent aerodynamic enhancements have taken its performance to a new level.  

    These aerodynamic performance gains have come about by focusing on three areas: deck shape, wing development and control lines and take-up. The following discusses in more detail each aerodynamic advancement.

    Deck fairing for deck sweeping sail. Similar to the AC Boats and A Class Cats, the Bieker Moth has been designed with a deck-sweeping rig in mind. A fairing panel on the deck aft of the mast enables the sail to be sealed onto the deck.  

    This feature reduces drag, makes the sail more efficient and allows the boat to get the most from the end plate effect.

    Wing Beams and Solid Wings.  The platform design minimises aerodynamic drag and heeling moment by using minimal tramp area.

    Stiff single piece wing beams located in rebated deck sockets maximise effective beam when heeled to windward through a curved, high angled shape.

    The wing beams are high modulus pre-preg carbon, constructed as a single piece using bladder moulding. They are designed to eliminate the need for compression struts and unnecessary joins. This rigid wing frame also reduces windage and streamlines the platform.

    The solid wing option reduces aero drag and makes the boat faster to tack and gybe.  This wing also enables sailors to impart kinetic energy into the boat during tacks and gybes.

    Internal Take-ups and Controls. The take-ups from the control lines have been designed to run inside the solid wing which further reduces drag. This concealed control system along with the control line configuration makes for a clean deck layout.

    The Bieker Moth is continuously evolving to incorporate feedback from sailors and latest design thinking. We're proud to be building these speed machines.

    For more information contact Dave McDiarmid; david.mcdiarmid@mackayboats.com or James Gell; james.gell@mackayboats.com

    World Sailing Licensed Builder
    Member of NZmarine



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    • 24 Manga Rd, Silverdale
    • Auckland, New Zealand
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