Class History

The International Moth has one-design roots, but 30 years of developmental rules have metamorphosed the early Moth's 110- pound, flat-bottomed hull into a 22-pound speed machine. Today's 11-foot single-handed Moths foil in 6 knots and kiss 30 in heavy air. The current design earns its international name—it is the fusion of the American Moth Boat, Australian Inverlock, Swiss-inspired hiking wings, and a hydrofoil from the UK. moth_sailplan.gif

Boat Specifications

Length overall: 3.355 m
Beam: 2.250 m
Max. luff length: 5.185 m
Max. mast length: 6.250 m
Sail area: 8 m



Moth Systems3" Wire Block - 30016mm Double Block - 40616mm Double Block - 40616mm Single Becket Block - 40529mm Pivoting Lead Block - 39629mm Pivoting Lead Block - 39616mm Triple Block - 40829mm Carbo Fixed Head Block - 35216mm Single Block - 40457mm Carbo Ratchamatic - 262540mm Carbo T2 Lashing Block

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Due to strong apparent wind caused by the speed of foiling, flattening the sail with the downhaul makes the boat faster and easier to control. 6:1 double-ended downhauls are common, but racers like Bora Gulari, '09  & 2013 World Champ, have used Harken 16 mm blocks to create even higher purchases.


Vang tension is critical in generating the power to lift off. The 16:1 double-ended system also allows for "vang sheeting" upwind to control shape and twist.


The Ratchamatic® ratchet disengages under light loads to allow fingertip control. Ratchamatics and T2™ Blocks have strong ball bearings on curved races to make secondary bearings unnecessary-which means adjustments are lightning fast under any load. Many racers add an additional block for a 4:1 system to reduce sheet load.

Moth Top View

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  • United States
  • Australia
  • France
  • Italia
  • New Zealand
  • Polska
  • Sverige
  • UK