Moth (dinghy)

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International Moth
File:Moth Kiel2008.jpg
An International Moth Class sailing hydrofoil flying over the water.
Class Symbol
Current Specifications
Crew 1
Type Monohull
Design Development class
Construction Carbon Fiber or Fiberglass
LOA 11 ft (3.4 m)
Hull weight Unrestricted

The Moth Class is the name for a small development class sailing dinghy. There are three "species" of moths currently in existence: the International Moth, a fast sailing hydrofoil dinghy with liberal restrictions; the Classic Moth, a traditional dinghy with tighter restrictions; and the British Moth, a one design sailboat similar to those sailed in the 1930s.



The current International moth is a result of merging two separate but similar historical developments. The first occurred in Australia in 1928 when Len Morris built a cat rigged (single sail) flat bottomed scow to sail on Andersons' Inlet at Inverloch, a seaside resort, 130 km from Melbourne. She was hard chined, was eleven foot long, and carried 80 feet² in single mainsail. The craft was named "Olive" after his wife. The construction was timber with an internal construction somewhat like Hargreave's box kite. "Olive's" performance was so outstanding, that a similar boat "Whoopee" was built. Len Morris then sold "Olive", and built another boat called "Flutterby", and with those three boats, the Inverloch Yacht Club was formed. Restrictions for the class known as the Inverloch Eleven Footer class were then drawn up, with the distinguishing characteristic that of being not a one-design boat but rather that of a boat permitting development within the set of design parameters.

At much the same time, 1929 in fact, halfway around the world another development class, the American Moth Boat was started by Captain Joel Van Sant of Atlantic City, New Jersey with his boat “Jumping Juniper” built of Atlantic White Cedar from the Great Dismal Swamp. The major difference between the Australian and American boats early on was that the American boat used only 72 feet² of sail on a somewhat shorter mast. The US development class was formally organized in 1932 as the "National Moth Boat Association" and in 1935, due to increasing overseas interest, changed its name to the "International Moth Class Association" or IMCA.

In 1933, an American magazine, The Rudder, published an article dealing with the Moth Boat scene in US. The Australians noted the similarities between the two groups of boats and intuitively realized that the name "Moth Boat" rolled more easily from the tongue than "Inverlock Eleven Footer Class", and changed the name of their class to Moth. The Australians also noted the differences, particularly in sail plan between the two boats, but since this was in the middle of the great depression, and the two groups were 13,000 miles apart, no attempt was made to reconcile these differences. Thus two large Moth classes developed separately for over 30 years.

Early growth

Also, in the early 1930s a small group of sailors in Great Britain formed a British Moth Class. The British Moth class was restricted to a particular hull shape of a 1930s Vintage American Moth Boat, and is thus a one-design boat, not a development class. Meanwhile, in Australia, in 1936 the Victorian Moth Class Association was formed, but it was not until after WWII, that the NSW Moth Class Sailing Association was formed with foundation members coming from Seaforth Moth Club and Woolahra Sailing Club. During this time Australian Moths were using pre-bent and wing masts in the 1950s. From 1956 to 1961 all other states formed Moth Associations and in 1962 the Australian Yachting Federation (AYF) recognized the Australian Moth class as a national class, the FIRST small boat class in Australia to be granted national status.

After the second world war, more and more European interest in the Moth Boat was expressed. The European Moth clubs subscribed, more or less, to the US class rules. One European Moth design from the early 1960s, the "Europa Moth", broke away from the IMCA and formed the one-design Europe dinghy class and became the woman's single-hander used in the Olympic games from 1992-2004. Also in the 1960s, the Australian Mothists began campaigning for rules changes that would permit the Australian Moths to compete in the IMCA's "World Championships".

International Moth Class

In 1971 the US-based IMCA completed a phase-in of new rules which attempted a "marriage" of the IMCA and the Australian Moth. This amalgamation process had started at the annual IMCA meeting in 1965. New rules embraced the larger, more powerful high aspect, loose footed, fully battened rig of the Australian Moth. The new rules also permitted controversial hiking wings first seen on Moths from Switzerland. Finally, the rule change abolished the US centralized organization of the class in favor of an independent world body with equal-partner national associations. Each national association elected its own officers and world body representatives. The culmination of these changes was the recognition in 1972 of the IMCA by the International Yacht Racing Union (the forerunner of today’s ISAF) bound by the agreed upon new restrictions of the class (with metric measurement conversions) operating today. The moth class association that had originated in the US was now truly an international organization.

Being a development class, the moth has evolved from a hull in the 1930’s that could best be described as a heavy, narrow scow or a blunt nosed skiff, (weighing about 50 kg) to today’s remarkable foilers with hull weights of under 10 kg,. Designs have run the gamut from wide skiffs without wings, to lightweight scows, to wedge-shaped hulls characterized with narrow waterlines and hiking wings out to the maximum permitted beam. Likewise, the sail plan has evolved from cotton sails on wooden spars, through the fully battened Dacron sails on aluminum spars stage, to the windsurfer inspired sleeved film sails on carbon masts seen today.


In the United States in the late 1970s participation in the International Moth class died and the class growth and interest moved to Europe and Australia. After ten years of little moth activity in the US, several sailor started looking for old Moth Boats with the original US rig to restore and race. A newsletter was started to aid communication between like-minded Mothists. Racing of "Classic Moths" resumed in 1989 and in 1990 a new club was formed to govern racing and construction of Classic Moths. This club, the Classic Moth Boat Association or CMBA is the current governing body for the original US type of Moth Boat. The intent of the CMBA is to revive the original US version of the boat and update the rules so that development is permitted without allowing the boats to become too freakish. The IMCA rules from 1965, the final year prior to the phase-in of the Australian rig and wings were consulted as a starting point for reviving the US Moth. Those rules have been revised where necessary. Interest in Classic Moths has grown internationally, with new activity in Europe, primarily France.

Moth firsts

The International Moth has fostered a number of remarkable achievements. For example, in 1966-67, The King of Thailand was involved in the building of three Moths and sailed them on the pond at Chitrlada Palace. The King raced for almost 20 years on his second moth called 'Super Mod' until his design and construction efforts were cut short by the 'press of royal duties'. In 1957 Patricia Duane became the first women to win the moth world championship in her Cates-Florida design and in 1968 Marie Claude Fauroux became the first woman skipper to win a World dinghy racing title from a IYRU sanctioned international class - in her Duflos designed moth. The International Moth was selected as an official training class for the Japanese Olympic sailing team, to hone their balance skills.

Perhaps most spectacularly, recent years have seen the International Moth literally take flight with the advent of lifting hydrofoils on daggerboard and rudder, which lift the entire hull and skipper above the water surface, dramatically reducing drag and increasing speed. Top speeds achieved are above 30 knots, the highest 10 second average of 30.7 knots[1] (56.9 km/h) was recorded on 2 May, 2010.

Class growth

Since the addition of hydrofoils to the boat, the International Moth Class has experienced remarkable worldwide growth, including a resurgence in the United States. The moth has become the standard of a successful hydrofoiling class, with most foils and control systems based on developments by John Ilett in Australia. As such, it is currently one of only two practical foiling monohulls, the second being the foiling version of the RS600, though recently the R-class skiff in New Zealand has seen some boats add hydrofoils as well. There are now several manufacturers supporting Moth fleet growth, including Mach 2 boats (Australia/China), Bladerider (Australia), Aardvark Boats (UK), and Assassin (New Zealand). New boat costs run from around $13,000 to $17,000 USD, though used hydrofoil boats can be had in most active countries for less than half that, depending upon condition, pedigree and vintage.

Areas of rapid development in the class currently (2009) include hull shape, rig (sail and mast), hydrofoils, and foil control systems.

Recent events

The 2011 International Moth World Championships will be in Belmont, Australia on 8-14 January 2011[2]. This event is building to be the biggest Moth Worlds in a long time, with over 100 foiler, 20 scow and several skiff Moths expected to compete.

The winner of the 2010 PUMA International Moth World Championships, sailed in Dubai in March, was Simon Payne[3] (GBR) in a Mach 2 over Andrew McDougall (AUS) - also in a Mach 2. The series was noted for its light air, with last year's champion Bora Gulari (USA - 6th) using the race with the strongest breeze to record his only win of the series.

The 2009 International Moth World Championship was won by Bora Gulari on a Mach 2 over 2009 World 49er champion Nathan Outteridge sailing a Bladerider (2009, Columbia River, Oregon, USA). This regatta was notable for the caliber of the competitors it attracted, including many full-time professionals, Olympic champions, and World Champions in various fleets. Gulari's victory was a remarkable achievement and spoke volumes about how learning to push the boat very hard and optimizing control systems can pay dividends against very smart but less foiling-savvy competition.


External links

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