A History of Change

During this 75 th year of the Moth class in Australia, it is quite amazing to see that this small and dynamic development class continues to create incredible interest in the international sailing community. This article takes a brief look at the recent extraordinary developments within the International Moth class and how it is coping with the current changes.

The International Moth class, by its nature encourages continuous development and change. This is not always easy to accept, as some changes have made the entire fleet obsolete overnight. This happened when the Australian Moth class went international and wings were allowed in 1969, when Ian Brown won the Moth NZ Moth worlds in 1973 in a fat skiff and yet again when Clive Everest and Roger Angel introduced the current narrow skiffs to win the 1990 Ratzeburg Moth Worlds. In each case we had to update the entire fleet with the new breakthrough designs. While this temporarily caused disruption, the end result in each case was a far improved design and many new boats being built.

I can imagine the consternation of the current Skiff Moth sailors at the realization that Foiler Moths have now arrived, are very fast and are here to stay! Should I go out and spend $3-4,000 on a set of new foils? How on earth would I build a set of foils anyway and how much would it cost? Do I want to sail with foils at all? Will I be able to manage them?...... The decision is not always easy, but one consolation is that at least the boat and rig are not obsolete...I just need foils!

The only real precedent for the effects of such radical design changes I am aware of, is within the Moth class itself. Given the current situation and recent votes to continue to allow foiler development within the Moth class, perhaps the best approach now is to drop any doubts or negative sentiment and simply “give it a go”!! In fact I would encourage all Moth sailors to do just that ! The more competition and the faster the change, the better and more stable will be the future of the class.

On the positive side, in winds over about 7 kts all boats can now be equally competitive whether they be narrow skiffs, fat skiffs, or even scows. Foils give a exhilarating burst of acceleration and a smooth quiet ride, very like low level flying or gliding…an amazing feeling. Also, inspite of how difficult it looks in the photos, balancing on just the centreboard and rudder, in fact the boat is much wider underwater and more stable then when displacement sailing. Narrow unstable boats can therefore become more stable and all boats have the potential to be 15-20% faster than the fastest skiffs today, while Scows could easily double their speed! Imagine breezing effortlessly past most of the current skiff and catamaran classes upwind and down!

The field is therefore completely open to new development ideas and we are most likely at the equivalent development stage as the original very fat skiffs from 1970, compared with today’s refined machines! Burville and Ilett have clearly demonstrated that Moths have sufficient power to weight in order to fly on foils, that they are faster and more efficient than displacement or planing hulls when sailing in over 6 knots of wind and ride height can be automatically controlled. To give an example, it should be possible to foil on a Moth in as little as just 5 kts of wind and also reach a top speed of around 30-35 kts in 20-25kts of wind!

Currently we are managing to lift clear in 7kts of wind and reach a maximum speed of 22kts compared with around 17kts maximum for skiffs without foils.

The introduction of foils is just one further step in the amazing development of the International Moth class which can be seen in the progressive lowering of their yardstick over the past 75 years. Unlike recent developments in the Skiff classes, where the formula for speed is primarily based on larger boats with more power, through larger rigs and lots of righting moment, Moths have made improvements based on high efficiency, concentrating on light weight and low resistance. Each small improvement results in higher speed, which creates higher apparent wind, so “the faster you go, the faster you can go!”

Since 1930 Moths have an unparalleled improvement in their performance and just when it seemed they had reached stability with the ultimate displacement skiff design, along comes a new development and a further 20% jump in performance. I am sure there is even more to come!

Dinghy Foilers

“Dinghy Foilers” were only dreamt about until 6 years ago and are now a reality! Winning a championship of any kind on foils has never been achieved before in any International sailing class. Rohan Veal has certainly shown in no uncertain terms that this is now achieved.

Foiling craft of all types and even foiling sailboats have been around for many years, primarily on multihulls and even sailboards, but mastering dinghies on foils has been one of the last frontiers. While the potential has always existed, it was not until relatively recently that foils have been put under Moths with any success. These first attempts were with trifoil arrangements, which showed what was possible, but this effectively made Moths multihulls.

It was not until quite recently, in 1998 that it was first proven that using centreline foils placed just on the rudder and centreboard was even practical! . I suspect this had not been done before simply because it was not thought possible. This “bifoiler” arrangement exhibits quite different behaviour from trifoilers and so it now becomes possible to distinguish a completely new breed of dinghy type, termed the “Dinghy Foiler”, which the International Moth class is now fostering.

Dinghy Foilers are the latest extension of a natural development in monohull design, each becoming progressively more efficient. This trend is depicted in the diagram below:

Moth & Dinghy Foiler developments

Moth Dinghy Foiling has been developing quietly for the past 6 years or so.

The initial version, first sailed in 1998 was based on the Hobie Trifoiler arrangement. It was quickly realized that while fast enough in a breeze, these contraptions are quite impractical to rig & launch, complex and above all incredibly stable, making it quite boring to sail and clearly not what a modern dinghy class is about.

    
Ian Ward sailing the first ever “Bifoiler” Dinghy Foiler, Sydney, November 1999.

In response, the “Bifoiler” arrangement was developed and first sailed in1999. This was the first time any dinghy had sailed on just rudder and centreboard foils alone. It solved all of the major problems of the Trifoiler arrangement and proved that it was feasible to sail on centreline mounted lifting foils.

In 2000 Brett Burvill independently introduced the simple trifoil arrangement with surface piercing wing mounted foils. This went very well in many conditions and certainly put foiling Moths on the map, winning a couple of heats of the Moth Nationals in Perth. There were some handling difficulties and it had some practical problems to rig and launch. Above all however, it was seen as a highly stable contraption and in effect turned the Moth dinghy into a multihull.

Brett Burvill sailing his trifoiler Moth in Perth, 2000

Understanding that it was practical to foil on just centreline mounted foils alone, the International Moth Class Association voted to outlaw wing mounted stabilizing foils, interpreting these as contrary to existing rules. This is because these were heading in the wrong direction, turning Moth dinghies into multihulls and introducing problems in handling, launching etc. In fact no new rules have been introduced to restrict foil development.

This effectively meant that centreline mounted foils became the only practical option for those wanting to use foils.

John Ilet’s bifoiler in Perth, 2002

In 2002 John and Garth Illet took up the considerable challenge and quite independently built their own bifoiler arrangement. They have very creditably solved the significant control problems and John has produced an excellent product which is available from Fastacraft.

Rohan Veal bought a set of these foils and mastered the settings and his sailing technique in a short time span to come 3 rd in the recent 2003 World championships in France and convincingly win the National titles in January 2004, impressively some 20% faster than the current top Moths without foils.

Rohan Veal winning the Moth Nationals on Lake Cootharaba, January 2004 using Ilet foils.

This bifoiler arrangement has certainly proven very successful, already being introduced in Japan and the UK. The ease with which sailors have mastered sailing with foils indicates that they are in fact simpler to sail with than an ordinary narrow skiff Moth hull in displacement mode and it only takes a few sails to get used to this.

Not only that, but the bifoiler has proven itself to outperform the original trifoil arrangement in terms of rigging, handling, speed around the course and race results. It also removes the general impression of Moths being highly stable multihull contraptions and has placed them in the realm of highly sophisticated racing dinghies, what I would term as the first ever true “Dinghy Foilers”.

While “bifoilers” are by far the best solution available to date, they are by no means the only or simplest solution for Dinghy Foilers. Another potential solution under development is a “Unifoiler”, which consists of a single lifting foil on the centreboard with a canard at the bow acting as a sensor. This arrangement is potentially much simpler than a bifoiler, as the main foil does not require control flaps or sensor connections. No rudder foil or outrigger modification is required either. Just slip the centreboard foil in the case and go!

The canard can be fixed or fitted with a sensor, surface running or immersed. Many variations are currently being trialled. It can also be easily retracted as it is small and only has light loads applied to it. The key benefits are simplicity, low cost and lift is on only one foil which is working at maximum efficiency all of the time. Extra surface area is available for initial lifting but is reduced when the surface running sensor canard foil leaves the water.

The Unifoiler concept was first applied by Rich Miller to his foiling sailboard in California. To date only one dinghy has ever flown as a Unifoiler. It is a wingless scow Moth, which is used as a test platform for foiler developments. This photo illustrates what is possible in just 6-7 knots of breeze!!

Ian Ward sailing the first ever “Unifoiler” , a foiling Scow Moth, Sydney, March 2004

The race is now on to establish even better & simpler height and pitch control. Being able to compare real improvements within a proper racing forum is exactly the benefit of competing within the Moth class.

Misconceptions

There has been an enormous amount of international publicity on foiling Moths recently, mainly due to Rohan Veal’s single handed efforts. This has resulted in an incredible amount of interest, which hopefully will result in new Moths hitting the water and more boats racing regularly.

Sailing magazines around the world are now interviewing top sailors of various classes and commercial organizations, about their views on Dinghy Foilers. Surprisingly, they have not interviewed the small core of people currently developing these fascinating craft, nor have these commentators sailed Dinghy Foilers themselves or recognised the true differences! They therefore seem to have presented some significant misconceptions about foiling, how it works, the pros and cons and the role of the International Moth Association in managing this significant step change in sailing craft design, within an existing class.

The key areas where they are seem to be getting it wrong are surprisingly to do with the very basics:

• Stability
  Firstly, sailing on foils is significantly easier than it looks or is believed from those dramatic photos with boats high in the air, In fact they are far more stable than existing Moths without foils. This is due to the dynamic stability generated from a foil which is around 800mm wide under water, as opposed to the 300mm wide displacement hull. This in fact means that foils could easily be applied to any light, highly powered craft and be quite easy to sail, including old scows! It also means Moths are no longer the highly unstable craft they appear.
  
• Dinghy qualities
  Based on the above misconception, several designers are still trying to add stability to dinghies by using a wide foil base, with large surface piercing, wing mounted contraptions. This concept may look flash in the graphics but is not only ungainly, riding very high out of the water, but it makes the boat rigidly stable with a large righting moment, like a catamaran and so the boat looses its “dinghy” responsiveness. In essence it makes the boat a multihull and removes the skills and challenge of balancing and sailing a dinghy.
  
• Dinghy Foiler
  By heeling the Dinghy Foiler to windward, not only does the rig produce some lift, but also the weight of the skipper, rig, and hull are now out of water and to windward of the centre of lift. These forces are all working together to provide significantly increased total positive righting moment. This is even more efficient than for a sailboard, as the hull itself is now also contributing to the righting moment. This effect is only possible to achieve with a true “Dinghy Foiler” arrangement with lifting foils on the centreline of the hull. Only a small heel angle is required to get a significant benefit.

• Upwind
  When sailing upwind, even with the hull still partly in the water the foils provide very significant lift, which is proving to be more efficient than straight displacement sailing. The best foiling Moths have consistently shown they can sail both higher and faster upwind than even the very efficient existing Moths. This is an incredible feat, and means that Dinghy Foilers are not just one tack speed machines like most multihulls and sailboards.
  
• Tacking and Gybing
  Initial perceptions might indicate that foiling is OK for straight line sailing, but what about tacking and jybing. Surely you could expect them to sink in the water and take a long time to get going, just like tacking a catamaran or sailboard.
  Well amazingly this idea is wrong too! As there is almost no boat in the water, they tack on a dime and simply keep going! They even sail through jybes, maintaining high speed and are easy to handle. Well sailed, they are actually faster to tack and safer to jybe than conventional Moths!
  
• Tactical racing
  Tactics are a critical part of dinghy sailing. As Dinghy Foilers have been found to actually go higher and faster upwind and even tack faster than conventional boats, the ability to race tactically is not only preserved but may even be enhanced!. There is a real opportunity for close tactical upwind racing, along with bursts of blinding speed off the breeze. This has been a key feature the Moth class has been keen to foster and preserve. It would even appear that these craft are fast enough to tack downwind as well, thus increasing the tactical skills required when racing!
  
• Height control
  The most difficult technical aspect to foiling is maintaining height control and countering longitudinal pitching. The technique employed currently on bifoilers utilizes a sensor wand activating elevators on the main centreboard foil. This induces some significant height variations which result in the boats sometimes flying seemingly out of control high out of the water and sometimes the hull touches the water. While it would be better to have level flight only just above the waves, this is not always possible with the current arrangement. This is certainly one area that is still being developed. The Unifoiler offers one potential solution.
  
• Displacement performance
  In light wind displacement sailing mode, foils can slow the boat. Experience has shown that by moving bodyweight forward or raking the foils, allows the lifting foil to run at zero angle of attack. This produces no lift, and significantly reduces the resistance. It is even possible to very disengage the foil so that it runs free, offering very little resistance. By keeping the boat light and foil size to a minimum, it is gradually being found that even when displacement sailing, the foils are not as big a disadvantage as first thought.
  
• Sensor simplicity
  In its most basic form, the height control sensor consists of just two moving parts, a wand which adjusts the lifting foil attitude. Some arrangements can even operate with no moving parts at all. Given the over complexity of many high performance craft today, it is incredible that both sailors and even designers should see the sensor as something rather “complex”. I suspect it is simply that its function and mechanism are not properly understood.

The role of the International Moth Class Association (IMCA) in administering class development during this major period of immense change also appears quite misunderstood, especially to those who have not so far been involved in the developments or even sailed foilers.

Even in a development class it is important to provide some restrictions to preserve the class, competitive racing and practical boats people are prepared to sail. All development classes have found some restrictions necessary over time, so much so that 18 footers have become a substantially one design class and all but one of the existing development classes, including A-class catamarans have banned lifting foils altogether.

IMCA by contrast has kept a close eye on the new innovations and has sought to encourage development in accordance with the class charter. The aim being to introduce foiling as simply one further stage of a natural development of the sailing dinghy, rather than a completely separate type of craft.

To manage this, it has been necessary to guide development in such a way as to produce a boat with the characteristics required for fair, competitive tactical dinghy sailing, requiring a certain degree of skill to balance and get the best performance. Unfortunately this has not always been seen in a constructive light and IMCA has been openly criticized for taking this approach. It is clearly not an easy task to balance the needs of the class to remain in existence, while fostering developments which could result in its ultimate destruction.

This concern of IMCA is not without foundation, as class numbers are already small and in fact very few of the developers of foiler Moths regularly sail at club or international level and only a few foiling Moths race regularly at present. It is hoped that the basic facts outlined for the first time in this article will help people to understand the decisions taken.

Only the Moth class has stuck to its charter and traditions and allowed such developments. This has not been without a lot of internal soul searching and debate. But finally a brave and historic decision has been made to proceed. So now we can all see the further exciting developments which will most surely follow.

Dr. Ian Ward
(Past President IMCA, Developer of the first Dinghy foiler, Bifoiler and Unifoiler Moths)

New Terms introduced:

Dinghy Foiler: A monohull dinghy using centreline mounted lifting foils. Relying on the crew to provide significant proportion of the stability. This arrangement reflects Dinghy handling characteristics as opposed to highly stable multihull arrangements. Dinghies with wing or gunwhale mounted foils providing lateral stability should not be termed “Dinghy Foilers”

Bifoiler: A dinghy foiler utilizing only two main centreline lifting foils, usually one on the centreboard and another on the rudder. This arrangement usually involves a sensor controlling the lifting surfaces to maintain height and counter pitching.

Trifoiler: An existing arrangement used on Hobie Trifoiler and Rave hydrofoil multihulls and where the hull is supported on 3 foils in an arrangement providing significant lateral stability and righting moment.

Unifoiler: A dinghy foiler with a single main centreline lifting foil only, usually on the centreboard. This arrangement also involves a sensor of some kind, generally a forward canard, which may be surface running or subsurface. The canard is usually very lightly loaded and is used as a reference to set the ride height and counter severe pitching moments. The skipper moves body weight to keep the canard unloaded most of the time. This arrangement is potentially more efficient and simpler than the bifoiler arrangement and can operate with no moving parts.