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Moth Sailboat Parts & Equipment

Block - 16mm Single - Becket

Block - 16mm Single - Forkhead

Block - Fly Block 18mm Single

Block - 16mm Double

Block - Fly Block 18mm Double

Block - Carbo T2 40mm Single

Block - Carbo T2 Ratchamatic 57mm Single - Standard Grip (Black)

Class description.

The International Moth is an eleven foot long, high performance, single handed racing dinghy. It is proud to be one of the few development classes left in the world and have very few design rules including no weight limit. The class encourages innovation just as much as it encourages sailing skill. It welcomes home boat building and wacky designs, and almost importantly, it welcomes unconventional people with open arms. This offical Australian Moth web site has all the latest National information that you need to start Mothing right now. 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. 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.

Class Specs

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How to home-build a Moth - James Sainsbury's step-by-step guide!

Related Articles

MACH2 Essentials

All you need to know about the Moth class and Mach2 in particular. All the essential information regarding the boat, it's history, evolution of foiling, the designer, the sailmaker and the boat builder. There's even an introductory video and a few testimonials. Enjoy!

The Designer

Andrew 'AMAC' McDougall first became involved with the Moth class when he built his first Moth at the age of 15 in 1970.

Need some parts for your Mach2? We have a full compliment of sails, spas, foils and Mach2 spares available online.

Speed Demons

36.6 ned goss.

Is this a world record speed for a dinghy? Ned Goss in a 18-25 knot Charleston sea breeze hit a peak speed of 36.5 knots, with a 10 sec average of 35.9 knots in his MACH2. Goss’s Velocitek files were verified by Bora Gulari & Velocitek founder Alec Stewart. Take that!

30.2 Josh McKnight

Following his win at Lake Garda, 2012 World Moth Champion, Josh McKnight then set an outstanding top speed and ten second average on his Mach2. It goes to show the Mach2 / KA Sail is a killer combination!

31.5 Scott Babbage

Scott Babbage set this speed sailing his MACH2 on Sydney Harbour whilst training with Josh McKnight. Any top speed that's above 30 knots is well worth a mention, but to have a ten second average that is also above 30 knots, wow!

31.4 Hiroki Goto

Sailing at a lake in Japan near Mount Fuji, Hiroki Goto, set a very impressive top speed of 31.0 knots, only to surpassed his on record the following day with a top speed of 31.4 knots and a ten second average of 28.4 knots.

MACH2.6 Is Here

This is the fifth major upgrade in the illustrious life of the Mach2 Moth. Already it's proving to be dominant. For the complete list of upgrades and features, hit the link below

Testimonials

We take a great deal of pleasure designing, building and supporting the best foiling Moth in the world. And nothing gives us greater pleasure than the positive feedback we have received from MACH2 owners over the past 10 years. Here's a few owner testimonials........

Thanks for Visiting the MACH 2 Website

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Mach 2.5 Aero Wing Kit - Dacron Tramps

Mach 2.5 Aero Wing Kit - Hydranet Tramps

Mach 2.5 Aero Wing Rope Kit

KA Moth Sail MSH5.3

KA Moth Sail MSH5.4

Mach2.6 Hull Conversion Carbon Kit

Mach2.6 Hull Pull Rod Kit

Mach2.6 Bowsprit Assembly

Mach2.6 Gearing Assembly Kit

KA Moth Sail MSH5.2

Ronstan 20mm Orbit Block High Load

Ronstan 30mm High Load

Mach2.6 Ride Height Adjust Kit

Mach2.6 Ride Height Adj Barrel assembly

Mach 2.41 Front Foil Horizontal with Cover

Mach2.4 Bent Boom

Mach2.5 Aero Front Wing Bar - Left

Mach2.5 Aero Front Wing Bar - Right

Mach2.5 Front Wing Bar Socket Reo Left

Mach2.5 Front Wing Bar Socket Reo Right

Mach2.5 Aero Rear Wing Tube Left

Mach2.5 Aero Rear Wing Tube Right

Mach2 Rear Wing Bar Socket Reo

Mach2 Mast for MSH Top Section

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Classic Moth Boats

Classic Moth Boats are a class of small fast singlehanded racing sailboats that originated in the US in 1929 by Joel Van Sant in Elizabeth City, NC. The Classic Moth is a monohull development class using a modified version of the International Moth rule in effect pre 1969. With an eleven foot over-all length, a maximum beam of 60 inches, a minimum hull weight of 75 pounds, 72 Sq Ft sail area, and very few other restrictions a Classic Moth can be a skiff, pram, scow, skinny tube, dinghy, or any combination thereof. The Classic Moth Boat is an ideal class for amateur designers builders and tinkerers, and can be easily built from inexpensive materials.

If you wake up in the middle of the night with a novel idea for hull shape, you can leap out of bed, race down to your garage, build it and then find out at the next regatta if your idea is hot or not. Freedom of design sets Moths apart from the clorox bottle (one-design) crowd. Instead of the one design controlling who sails successfully, we design and build Classic Moths that fit our size, ability, taste, skills, artistic expression, and pocketbook.

To broaden the appeal to race all types of Classic Moths, we have created three divisons within the class. At major regattas, all Classic Moths race together but are scored in three different divisions; a Gen 2 division for full on narrow waterline, low wetted surface designs, a Gen 1 division for more stable, higher wetted surface designs, and a Vintage division for restored Moths built before 1950.

Presently, Classic Mothboats race in many locations up and down the east coast of the United States. Regattas are currently held in Brigantine, NJ; Portsmouth, VA; Chestertown, MD; Cooper River, PA; Augusta, GA; Norfolk, VA; Elizabeth City, NC; Charleston, SC., and St. Petersburg, FL. Please refer to the regatta schedule on this site for dates and contact information.

Latest News

2022 mid winters results.

2021 Nationals Results

2020 Nationals Results

2019 race schedule..

We have quite a race schedule for 2019.   

Check it out under Schedule. 

Happy Sailing  

Europe Dinghy in FL

Europe dinghy with

carbon fiber mast, aluminum Proctor boom,

wood dagger board, fiberglass rudder,

Cunningham, vang.

2 sails - practice sail and North racing sail.

Asking $1500.

early Ventnor

This is an early Ventnor with an unknown registration number. 

Sun Fun Sailor built from plans in Science & Mechanics Oct 1962

Hi, I wish to advertise and sell my Moth built by my brother in the 1960’s   For Sale : Sun Fun Sailor built from plans in Science & Mechanics Oct 1962.   Includes trailer and 2 sails. Wood construction hull, mast and boom. Hull bottom was fiberglassed when built in the 1960’s.   Located in Appleton Wisconsin.   Asking $900.00.      Contact Ron Aavang @  This email address is being protected from spambots. You need JavaScript enabled to view it. document.getElementById('cloak05df24d1c436f6a276e1a4559c7ebc73').innerHTML = ''; var prefix = 'ma' + 'il' + 'to'; var path = 'hr' + 'ef' + '='; var addy05df24d1c436f6a276e1a4559c7ebc73 = 'raavang' + '@'; addy05df24d1c436f6a276e1a4559c7ebc73 = addy05df24d1c436f6a276e1a4559c7ebc73 + 'new' + '.' + 'rr' + '.' + 'com'; var addy_text05df24d1c436f6a276e1a4559c7ebc73 = 'raavang' + '@' + 'new' + '.' + 'rr' + '.' + 'com';document.getElementById('cloak05df24d1c436f6a276e1a4559c7ebc73').innerHTML += ' '+addy_text05df24d1c436f6a276e1a4559c7ebc73+' ';  or call cell # (920)904-2167.

Member Links

• Mid-Atlantic Musings
• Europe Dinghy Moth
• John Shelley's Moth Boat
• Blackberry Boatworks
• Earwigoagin
• The Madmothist
• Classic Moth Boat Facebook Page

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MAVERIK MOTH

This is just the beginning…

We have a long standing heritage in composites and pride ourselves on innovation and a passion for what we do.

Introducing the Maverik…

Design for manufacture

Customisation, power module.

Say hello to the “Henchley”, a solid state power unit designed to take all of the loads from the current Moth rig away from the boat and mast. A simple, elegant and innovative solution for today’s International Moth

In-Depth tutorial videos

Effortless assembly, support and updates.

The Maverik Moth is the culmination of many years of development with several new and innovative ideas…

Get ready to stand out

The maverik design speaks for itself.

Get in touch to discuss your next ride

Cert No. 12438-QMS-001

© 2024 Maverik Moth. Fluid Composites Ltd. All Rights Reserved.

• Maverik Moth

Fluid Composites Ltd.

Unit 4 Parkfield Farm Glaseby Lane Pulborough West Sussex RH20 4AX

T: +44 (0)1903 877441 E: [email protected]

- 2023 NSW and Australian Champion design

This Swift is a joint venture between Damic Design and our building partners to create what we believe is the fastest and best built International Moth on the market.

We have neatly 20 years of experience in the class which has helped immensely with the design and development of the platform. The end result is a boat that is easy to sail, looks great and most importantly wins races straight out of the box.

Please click on the link below for more information and pricing or to lock in your build slot.

The Concept

The Swift Moth has been designed with one main objective in mind, which is to be the fastest production Moth on the market!

This required a no compromise approach, so we have used the best available materials and manufacturing processed to achieve what we believe is the most thorough though Moth design to date. We settled on the final concept from over 55 different sub-variants to make sure the finished product is as close to perfection as we can get. The boat is also made in small batches that guarantee outstanding quality and finish that is simply not possible on a mass-produced build.

We focused on three key areas of improvement.

1.       Minimise aero drag

2.       Reduce overall weight

3.       Improve usability and ease of manoeuvres such as foil tacking.

We also wanted to make sailing more enjoyable though systems that work and excellent ergonomics. We made the platform fully dismantlable so that the whole boat can be packed in a box for low cost of transport to and from regattas. And lastly, we made the boat easy to live with so things like wing assembly, control lines take-ups and general maintenance are super easy and accessible.

When you buy the Swift Moth, you are not only buying speed and quality but access to advice and ongoing support from the Moth sailor and designer with nearly 20 years of class experience.

The hull shape has been primarily optimised for aero gains as we spend so little time in displacement mode. Though CFD and on water testing, our final shape ensures that the overall drag is very low. This is achieved by maximising attached flow not only top sides but also underside of the hull. Something that is particularly important in upwind sailing mode. We also tried to ensure that the airflow is accelerated over the forward section of the foredeck feeding clean air straight into the sail decksweeper. Hull volume has also been kept to an absolute minimum, but we raised the mid-section to help keep the front bars clear of the water for take-off in large waves but also to increase the effective aspect ratio of the sail and the hull. The Hull is made from carbon/foam sandwich construction with increased number of frames to ensure high stiffness at very low weight. The shell is available in any colour with striking clear carbon top sides.

The wing entire frame is a carefully engineered structure that is very light, stiff and aero. It also dismantles with just 4 bolts! The tubes are made from pressure moulded pre-pre carbon fibre with High Modulus used in the structure of the transverse bars. Solid trampolines then attach to the frame to make a super smooth transition to ensure attached flow over the entire structure. The trampolines also feature concealed rope take up channels and most importantly the overall concave shape helps reduce the mid-wing height making the trampolines feel less steep. This makes for easier boat handling, but while maintaining the advantage of a powerful platform though a high wing frame.

Control System and bowsprit

The Swift control system is based on one theory. The less linkages, the less slop! So, for this reason, our foil control tubes have the bare minimum of moving parts and linkages. And the ones that are there, have all been designed to eliminate slop. This all means you get more control and speed while sailing. The main carbon control tube sits on the deck floor and features what is now class standard gearing and bias adjusters. The bowsprit itself is a lightweight carbon tube with moulded end fitting that houses a titanium wand head for precision and weight reduction. The wand top tube itself is a custom carbon aerofoil section with adjustable wand inside.

Removable Foredeck

We paid a lot of attention to making the boat look clean so all the messy stuff like control system and rope take-ups are all hidden under the removable clear carbon deck fairing. When removed this fairing allowed easy access to everything that would might want to change. An access hatch above the mainfoil allows for connection of the pushrods, so the deck fairing only needs to be removed for maintenance purposes. We also extended this fairing a long way aft so that sail endplates on it removing the need for any additional fairings. The deck fairing is available to suit either 1050, 1150 or 1250DS sails.

Aero Wing Fairings

These components are optional extras, however we consider them as essential upgrades to the aero package. The wing fairings in particular are easily removable carbon mouldings that Velcro down and cover most of the trampoline control lines. They help guide the airflow over this usually messy area and reduce the overall drag quite significantly.

Toe-Strap Mouldings

This is another upgrade item that is designed to reduce the drag associated with traditional toe-strap mounts. Our carbon moulded alternatives are not only very aero but also allow for easy removal of the toe-strap though a single titanium bolt.

The gantry has been a big focus area as we consider it quite critical to improving take off performance. Our design not only offers low drag characteristics, but also water drainage at foiling speeds ensuring that boat is as light as possible in take-off mode. The gantry is constructed from carbon foam sandwich with internal framing that makes it super stiff yet very light.

The hydrofoil package comprises of our proven and race winning Swift range. The verticals we use are ultra-thin and short in cord while the horizontal range now consists of 5 foils. Three main horizontals and two rudder horizontals. All foils are a result of ongoing development since 2012 with a clear aim to push limits of design and materials in order to maximise performance well into the future.

• Performance Class

Over the years, CST Composites has experienced phenomenal success with the DS and ELITE range of masts and booms. The results speak for themselves, with multiple World Championships in the Moth class over the past 10 years.

In 2018 Paul Goodison won the Worlds using the DS1 Mast, which is targeted at the top end of the fleet. CST has worked closely with its Moth team sailors, always evolving and developing our product range in order to remain ahead of the opposition. Our primary objective is to make masts that suit popular sail brands and that work for a wide range of sailor weights. The result? CST sailors have more options than any other manufacturer, allowing them to reach new levels of performance.

Complete Mainsheet Hanger & Vang Attachment - suit 40mm Rectangular Boom

20 Series Carbon/Aramid Tiller Extension - Moth (1650mm)

Tow Pro Moth Boom

Moth Bent Boom Joiner

Moth Add-on Vang attachment for Mainsheet Hanger - suit 40mm Rectangular Boom

Mainsheet Hangers - suit 40mm Rectangular Boom

Tow Pro Pack

Tip Plug - Standard

Moth Moulded Carbon Forestay Tang - Standard

Moth Gooseneck - Standard

Moth Heel Plug (Female) - Tow Pro Series

Moth Heel Plug (Male) - Tow Pro Series

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INTERNATIONAL MOTH SPEED GUIDE

Moth Dinghy expert Rob Greenhalgh introduces this extraordinary singlehanded foiling dinghy and describes the keys to sailing one fast.

Who sails the foiling Moth Dinghy?

The Moth class is for everyone—it’s so exciting, you don’t need to race it. Club sailors can get a huge buzz out of foiling, going fast around the bay, and learning to foil jibe and tack. They might enjoy it so much they never need to join a race. At the other end of the spectrum, there are sailors who have been in Moth Class for a decade or more and love the challenge of racing this exciting, complex craft. 

Viewed from stern or bow, the foiling moth is a high-speed machine, clearly unlike other sailboats.

What kind of sailors enjoy this challenge?

Moths are development boats, not a strict one-design class, and that’s daunting for some. The technical and evolutionary side of Moth sailing requires a good understanding of how everything works—how the foils interact with the rig setup and how to balance both aspects. Over the last five years, there have been massive speed advancements, which will continue. To be at the top of the game, you have to enjoy the technical side. But you can buy equipment off the shelf and, if you practice and sail well, soon be up to pace. Though more technically oriented sailors often gain an edge for a while, there are also lots of people who will make changes that don’t help them, so it evens out.

How physical is the sailing?

When you are first getting into it, Moth sailing seems physically hard, but once you’ve done it a while, it’s not too bad. On a windy day with a lot of capsizing, it gets pretty tiring. But it’s a light boat, and the loads are not high. Anyone can do it if you can move quickly at times. There are plenty of Moth sailors in their 60s.

New boats or used, which are better?

My advice for the first-time or second-time buyer is to look for a good second-hand boat that you know will fly. This saves you a lot of effort, because even experienced Moth sailors need a few months to work up a new boat. Sure, it’s always a worry that you might not be getting good enough kit with a used boat, but in my experience, any modern Moth can be made fast. If you want to buy new, a standard boat from either of the two main builders—Exocet by Maguire Boats, or Mach 2 by MacDougall McConaghy—will quick enough for top 5. You can also have a look at the new Bieker Moth by LSF Composites.

The Moth is a development class. What’s happening lately?

The Vi-8 DS 3Di (on top) and Vi-8 LA 3DI feature the same sail area. The LA has more power in lighter winds to foil more quickly; the DS has less drag at high speeds.

What sails do you recommend?

8LA-3Di provides extra power to get on foil.

Which sails do you use?

The decksweeper (Vi-8 DS 3Di) creates an endplate and lowers aero-drag. It is slightly faster once foiling.

How does foil choice affect sail choice?

Moths have two foils, a larger foil for lighter winds and a smaller foil for stronger, and that’s a choice you have to make on the beach. In my case, if I expect to be on my foils all day, I’ll choose the smaller foil and the deck-sweeper sail. If the winds are lighter or less reliable, I will often choose the big foil and the LA sail. And if I expect light air to start but a building breeze all day, I’ll likely choose the big foil with the deck-sweeper sail.

Tuning the Moth Dinghy

What are the keys to tuning a moth.

Generally speaking, you should set up your boat to carry as much rake as possible. How much is that? You’ll know it’s too much if you can’t get under the boom in tacks and jibes. This is not something you do underway, and if the boom is making boat handling more difficult, make the rig more upright until that smooths out.

What other key adjustments do you make before launching a Moth?

Batten tension is one. For Batten 1 (the top batten) down to Batten 5, just take the creases out of the batten pockets—don’t over-tighten them. For Batten 6, remove the crease and then add two more turns by twisting the batten key two full revolutions in a clockwise direction. For Batten 7, take the creases out and add three turns. The outhaul is also non-adjustable underway. Rig the boat ashore with the outhaul loose. Pull on max vang and max cunningham, and then pull the outhaul tight. This will give you a good all round setting.

What other settings can you recommend?

Here some of the numbers from my boat, but don’t worry if your measurements are different. Comparing measurements boat to boat may not matter at all. The important thing is to start recording them and experimenting.

• Front Prodder 340 (adjustable +/-50mm)
• Side Arm 410mm
• Deflection 220mm
• Shroud Base 1500mm
• Mast Length 5100mm (excluding plastic plugs top and bottom)
• Back of mast to clew ring 2340mm

From mast length to shroud base, it's important to record all of your boat and rig measurements. You will change them over time.

How do you set up your foils, actuator wand, and gearing?

Sailing in rougher water requires faster gearing between your actuator and main foils. Foil gearing is a critical control for waves; make sure it can be adjusted for rough waters. To get through waves you need faster gearing. You’ll also change foil size depending on the wind forecast. I have two sets of main foils and use the smaller one on windier days. However, if the wind is light for the first race and predicted to build, I’ll go with the larger foil because the speed penalty of not being able to fly with other boats can trumps all other considerations.

Upwind Moth Sailing

What is most important when sailing upwind.

On any point of sail, the vang and cunningham are powerful controls, and need constant adjustment for different conditions. The goal is to generate power for low-riding and to get up on the foils, and then flatten the sail as the wind builds. One of the challenges of the Moth is it has a maximum 8.25 square meters of sail area, and upwind in most conditions, that’s more sail than you need. Downwind, you have the opposite problem; your speed reduces the apparent wind so much, you’re always starved for power.

What is low-riding mode and how do you sail fast in light winds?

In general you don’t race in winds when you can’t foil, but it may happen that the wind lightens up substantially during a race. Sailing in low-riding mode is an art in itself, something like balancing in a canoe because the hull is so narrow. I always recommend practicing sailing that way.

What does it take to fly a Moth?

Heel the Moth to windward to keep the boat more stable and reduce leeway.

Why do you tip the Moth to windward when flying?

We sail with the rig always tipped to windward because it keeps the boat more stable and reduces leeway on the main foil. Use very subtle steering and trimming of the main.

How do you trim the Moth sailing upwind?

Correct trim is the absolute key to good boatspeed. It’s very easy to over-sheet and stall the front of the mainsail. Always have the inside tell tales lifting. A common mistake is sailing under-powered and over-trimmed. As the wind increases, flatten the main by tightening vang and cunningham to accommodate the higher apparent wind speeds.

How do you adjust sail trim for gusty winds?

You need your rig set-up to be user friendly. That means having enough vang and cunningham to straighten the sail. If twisted, the center of effort can move up and down the sail. It takes a certain level of confidence to get to the point where you can let go of the mainsheet to tighten the kicker and cunningham.

Downwind Moth Sailing

What is the key to good moth speed downwind.

Sailing downwind, be sure to maintain a big entry angle in the lower part of the sail and avoid over-trimming.

What is your focus when trimming downwind?

I focus closely on my lower tell tales, keeping them flying 100 percent and making sure I ease enough to keep the sail ‘hooked up’ with airflow attached. I look for a nice big entry angle on the bottom part of the sail and clean up any horizontal creases by subtly tightening the cunningham. From there, it’s a matter of very subtle trim and steering. If in doubt, ease the sheet and be sure you have good flow going around the front of the sail. If you run into a light patch, just head up to keep the flow going on the main. If needed, power up the main even more. Get the gearing really slow on your foils to minimize drag. The boat will go faster and apparent wind will increase, moving the wind forward and letting you trim harder. Especially when it’s a bit lighter downwind, be sure to pre-empt a drop in apparent wind by easing main and bringing the bow up!

Moth Tacking, Jibing And Gear Changing

How do you foil jibe a moth.

When foil tacking or jibing, you need to flatten the boat. For jibing, bank into the turn to leeward. You’ll turn the boat more aggressively when your body is ready to move across to the new wing.

How do you foil tack a Moth?

When tacking you have to move quickly, bringing the boat relatively flat once head to wind. Start luffing slowly, taking the edge off your speed; make sure the boat is flat when head to wind. As my body moves across the middle to the new wing, I’ll increase the rate of turn, steering quite aggressively through the eye of wind, but my body has to be ready to cross the boat and receive the power on the new tack. You need to come out tipped to windward. Here’s how I break it down:

• Ten seconds before tacking, consider slowing the boat slightly and sailing slightly higher.
• Plan for a slow luff head to wind, followed by a faster turn rate once confident that crew weight can be positioned correctly.
• Heel to windward before the tack but flatten the boat once head to wind. Move your weight inboard. It is important here to sheet the mainsheet on centerline so that it is not over the leeward wing when you pass underneath.
• As you move across the middle of the boat, pass the tiller extension around the back and into a position halfway along the leeward wing.
• When you are confident you can move to the new side, increase the rate of turn, landing on a wider than close-hauled course.
• There are a lot of G-forces during this period, so expected to get ejected a few times!
• Don’t try to piece the whole tack together immediately. Practice the first phase of luffing head to wind, getting your weight to center, and switching the tiller extension across.
• Remember to ease mainsheet out of the tack and have your hands positioned so that the sheet can be eased quickly. The sheet is more important than the tiller on exit.
• I set my mast rake to allow 70 to 75cm between the boom and the deck where I cross the boat. Tacking is important, so make sure you have room under the boom! For tacking practice, I recommend having the rig more upright.
• Don’t adjust any control lines right before or after tacks, unless it is very light and foiling is marginal.

Name 5 key gear changes in a Moth

• To foil early in light air, power up by having the vang and cunningham as loose as possible. However, it is easy to over-deepen the front of the sail, requiring further bear-away to get good flow on the sail. Don’t overdo it.
• Downwind always requires a deeper sail shape than upwind, regardless of wind speed.
• Once foiling, immediately pull on vang to stabilize the sail and cunningham to clean the creases. Even though the wind is light, we are quickly doing 14/15kts. The AWS is high so we need to change sail shape to achieve good speeds.
• As the breeze builds, constantly increase vang and cunningham loads to achieve the desired sail shapes. Max vang should be achieved in 15 knots and max cunningham in 18 knots.
• The Moth gets overpowered quickly, and from 18 knots upwards a softer tip or different sail is required. North’s LA and DS designs have a slight variation in the luff rounds to cover the range, with the DS being aimed at 14 knots true wind speed. For lighter sailors, a softer-tip allows the mast to bend earlier and depower the sail.

How do you start a race in a Moth?

Starts are a bit chaotic. Even for long-time racers, a Moth start will be a new experience. People get up on their foils with about 25 seconds to go and do a big turn-up at about 3 seconds, crossing the lining at 20 knots. A key thing when you’re on your foils is to have the ability to slow down while maintaining control. You need to practice that. Getting to the pin too soon is dodgy, especially with boats starting on port tack.

Why do so many Moths start on port tack?

Moths travel at 15 to 18 knots upwind, so tacking is a very costly part of an upwind leg. Reducing the number of tacks during a beat is very efficient, although this depends somewhat on how well you tack and how confident you are in making your tacks.

How many ways can you capsize a Moth?

You will capsize a Moth every possible way when learning. But I can sail for days now without capsizing, unless it is windy and choppy. The key to recovering quickly is to get on the daggerboard and do a dry capsize, climbing back over the wing. Sometimes that’s hard to do, especially when you pitchpole and find yourself 20 meters out in front of that boat.

What is the most common boat-handling mistake in a Moth?

Capsizing! Foil tacking, in particular, is very difficult. A common mistake is trying to foil tack when it’s breezy. Drag is so high that as you go through head to wind, everything slows down and it’s easy to capsize. You may be better off planning to do a touch-and-go tack. 

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The international Moth Class is the fastest one Person Dinghy in the World.

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Rigging up a International Moth can be nearly as challenging as sailing one (nearly), especially when the breeze is up! This is especially critical with the pocket luff rigs.

It makes good sense to leave as much of your rigging in place at all times, even when trailing. Ideally the boom should be attached with the mainsheet, kicker and outhaul in place. Most helms also leave their cunnigham in place as well, using a quick release fitting or shackle. With all of this rigging in place an experienced Mothie should be able to rig a bolt rope sail rig in about 10-15 minutes and a pocket luff sail in around 20 minutes.

Pocket Luff sails

Pocket luff sails were reintroduced to the International Moth after a hiatus of about twenty-five years. The Lake Macquarie, NSW World Championships in 1994/95 marked the debut of this style of rig with many of the top Australian sailors unveiling the new breed of pocket luff sails. Since then many sailors throughout the world have used them. For more information on  pocket luff sails , please read an article written by Mark Thorpe.

The first step is to make sure that all of you control lines are slack so that the boom can be attached once you have the rig up. Then roll out your sail, making sure the zippers are on the topside if you have such a sail. Slide the mast into the pocket, I prefer to place the mast on top of the cambers as it is then easier to snap them onto the mast. You can either snap the cambers onto the mast before or after you put the rig on the boat, depending on your preference and type of sail. Although on a windy day it is easier to deal with the cambers and apply a bit of batten tension prior to hoisting the rig aloft.

Once you have dealt with the sail and mast it is time to attach it to the boat. Make sure that the rig will be facing into the wind once it is aloft. Tip the boat onto one wing and lie the rig across the mast stump with enough slack to attach the sidestays. Then attach the forestay, tying it loosely in place. Now you are ready to put the rig up. Stand with one foot on the wing bar, check that the stays are not tangled, or can snag on anything and raise the rig in one smooth motion. Once you have the mast in position in the mast stump, grab hold of the forestay and push forward, taking up the slack. You should be now be able to let go of the rig, holding it in place with the forestay. Now undo the half hitch you tied in the forestay and pull on some tension. Now your rig should be in place and you should be able to manage this on your own on all but the windiest of days.

Once your rig is aloft, the rest is elementary, attach the cunningham to the luff of the sail and pull on a little bit of tension. Then attach the boom to the mast, followed by the outhaul. Once this is done, you should be nearly ready to go sailing. One last point, on batten tension, it is easy to use too much. Especially in light airs, be careful because you may have problems with the battens popping onto the new tack.

I find that this technique works well and minimises the risk of dropping your rig onto your foredeck or elsewhere. Other techniques such as raising the rig up, putting it in the mast stump and then attaching the stays also works but you need a friend to assist you and on windy days even with two of you, it can be a bit of a handful.

Bolt Rope Sails Bolt rope sails have some advantages over pocket luff sails, they are simpler to maintain, rig and if set up correctly can generate more power and possibly more speed in light winds. The disadvantages are that in order to keep up with the pocket luff rigs when the breeze picks up, they generally need to be to be flattened off earlier using stiffer battens which help to keep the leech of the sail tighter and more stable/controllable.

First of all the mast track should be smooth and free from sharp edges, polishing the inside of the track can help the sail to slide up and down. The battens should be tensioned just enough to remove the vertical wrinkles in the batten pockets, any more and: You may have difficulty in flicking the battens over after a tack or gybe.

It could lead to damage as it puts excess strain on the ends of the batten pockets at the luff and leach of the sail.  Rigging is fairly straightforward, attach the shrouds, lift the mast onto the step and tension the forestay. Attach the boom, lean the boat over on its side and feed the sail onto the mast, connect the cunningham and pull on some tension This makes it easier to attach the clew of the sail onto the boom if you leave your kicker connected up. Then tension your sail controls according to the conditions.

Other tips The narrow International Moth designs are much easier to sail with some foam or an airbag in the outer wing pockets. There is a fine line between too much and too little. Too much will make the boat want to turn turtle immediately when you capsize. Too little will be of no benefit. Don't be concerned about the hardcore scoffing at you, all of the top sailors utilise some form of buoyancy in their wings. It makes the boats much easier to control in a breeze, especially when you are trying to keep you speed down prior to a start.

Another good idea is to have a piece of elastic on your tiller so that it is self-centering. Do not fit this too tight, just enough so that you feel a light resistance at five degrees of helm or so.

Another tip to make your capsize recovery as quick as possible is to have righting ropes under your wing bars so that you can lean back from the wing bar whilst you are standing on the centreboard to give you some extra leverage. Use a piece of ski rope with some elastic threaded through the middle, this will stay tidy and above the water when you are once again upright.

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• Sailboat Guide

Moth (International)

Moth (International) is a 10 ′ 11 ″ / 3.4 m monohull sailboat designed by Open starting in 1928.

Rig and Sails

Auxilary power, accomodations, calculations.

The theoretical maximum speed that a displacement hull can move efficiently through the water is determined by it's waterline length and displacement. It may be unable to reach this speed if the boat is underpowered or heavily loaded, though it may exceed this speed given enough power. Read more.

Classic hull speed formula:

Hull Speed = 1.34 x √LWL

Max Speed/Length ratio = 8.26 ÷ Displacement/Length ratio .311 Hull Speed = Max Speed/Length ratio x √LWL

Sail Area / Displacement Ratio

A measure of the power of the sails relative to the weight of the boat. The higher the number, the higher the performance, but the harder the boat will be to handle. This ratio is a "non-dimensional" value that facilitates comparisons between boats of different types and sizes. Read more.

SA/D = SA ÷ (D ÷ 64) 2/3

• SA : Sail area in square feet, derived by adding the mainsail area to 100% of the foretriangle area (the lateral area above the deck between the mast and the forestay).
• D : Displacement in pounds.

Ballast / Displacement Ratio

A measure of the stability of a boat's hull that suggests how well a monohull will stand up to its sails. The ballast displacement ratio indicates how much of the weight of a boat is placed for maximum stability against capsizing and is an indicator of stiffness and resistance to capsize.

Ballast / Displacement * 100

Displacement / Length Ratio

A measure of the weight of the boat relative to it's length at the waterline. The higher a boat’s D/L ratio, the more easily it will carry a load and the more comfortable its motion will be. The lower a boat's ratio is, the less power it takes to drive the boat to its nominal hull speed or beyond. Read more.

D/L = (D ÷ 2240) ÷ (0.01 x LWL)³

• D: Displacement of the boat in pounds.
• LWL: Waterline length in feet

Comfort Ratio

This ratio assess how quickly and abruptly a boat’s hull reacts to waves in a significant seaway, these being the elements of a boat’s motion most likely to cause seasickness. Read more.

Comfort ratio = D ÷ (.65 x (.7 LWL + .3 LOA) x Beam 1.33 )

• D: Displacement of the boat in pounds
• LOA: Length overall in feet
• Beam: Width of boat at the widest point in feet

Capsize Screening Formula

This formula attempts to indicate whether a given boat might be too wide and light to readily right itself after being overturned in extreme conditions. Read more.

CSV = Beam ÷ ³√(D / 64)

Single handed development class that has always been at the cutting edge of performance racing dinghies. The MOTH, raced today (2015), at the top tier of competition is a ‘foiler’ with wings.

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