Getting Up to Speed on Foils
November 4, 2009
By Lynn Fitzpatrick and Gino Morrelli
Chances are if you have spent most of your life cruising around on a sailboat, you know a bit about what makes sails work. Foils, canards and wings, however, may mystify you.
Imagine this daggerboard suspended from the leeward hull. The bottom hook provides upward lift and the more vertical section (the transition toward the hook in the other direction) provides lateral lift/resistance.
We’ve tried to simplify the principals for those of you who have a phobia for math, physics and applied sciences. What follows is enough to make you dangerous. Leave the applications of these principals to experts such as Morrelli & Melvin, who have rocket scientists, naval architects and engineers on staff.
Power Lifting with Bernouilli’s Theorem
Bernouilli’s Theorem is also known as the longer path explanation. A sail is an airfoil. Viewed in cross section, one side of the foil/sail is longer than the other. As the foil moves through air, the air splits at the leading edge (mast or headstay) of the curved airfoil. The air taking a longer path by passing along the backside/leeward side moves faster than the air passing across the front/weather side. The particles moving across the backside/leeward side of the sail are traveling farther in the same amount of time and they have a higher velocity, or speed, than the particles on the front side/weather side of the sail. They also have more room to spread out, forming a low-pressure area.
On the front side/weather side of the sail, the slower air particles are packed together more densely, creating a higher-pressure area. This difference in the pressure on either side of the sail creates a suction force, producing lift/power that makes the boat move forward… therefore sailing sucks!
Rudders, Keels or Daggerboards Create Side Force
All boats have rudders and keels or daggerboards that are essentially vertical airfoils underwater. The symmetric rudder creates lift by turning slightly relative to the flow, also called “angle of attack”. This slight rotation creates just enough difference in the distance the water has to travel around one side of the foil as compared to the other that it creates the same effect as air passing around a sail. The more we turn the rudder, or increase angle of attack, the greater differential in distance that water has to travel around one side versus the other, the more power we get and the faster we turn.
The primary job of a keel or daggerboard is to create enough equal and opposite side force or lift to counteract the forces created by the sails aloft. Sails push one way and the keels/daggerboards push the other way, and essentially spitting the boat forward like a watermelon seed pinched between your fingers!
In a traditional monohull the keel has to do the other equally important job of providing stability by suspending a ballast down low to counteract the heeling/tipping forces caused by the sails aloft. Rather than rely on deep and/or heavy keels, cats’ and tris’ stability comes from placing the hulls far apart.
Lifting Hydrofoils Push Boats Up
The same basic principles that apply to airfoils/sails, apply to all underwater hydrofoils. Rudders are symmetric vertical hydrofoils that turn the boat. Lifting hydrofoils are mounted horizontally and try to lift the boat. A typical asymmetric lifting hydrofoil on a boat is positioned similar to a wing on an airplane with the shorter/flatter side down and the curved side up. Because hydrofoils are much thicker than sails and the density of water is about 800 times the density of air, they are way more powerful for the same surface area.
Hydrofoil assisted boats float on the water while at rest. At low speeds they are not necessarily any faster than boats without hydrofoils. As speed increases, the hydrofoils generate more and more lift and push the hulls higher and higher out of the water. The hull is sometimes completely supported above the water surface by a strut. Free of the drag caused by the hull, a hydrofoil boat can skim over the surface of the water at over two times the speed of boats without hydrofoils.
Alinghi, Le Bouveret, Lake Geneva - 20/07/2009
Curved Lifting Hydrofoils do Both
Both the BMW ORACLE trimaran and Alinghi catamaran use curved daggerboards (hydrofoils) to provide necessary lateral lift/resistance and they also lift the leeward hull up. The same board is used to reduce sliding to leeward or leeway and also provide vertical lift. The current variations that are being experimented with by both teams, tradeoff more vertical lift for less lateral lift or vice versa. Upwind these boats still need a fair amount of lateral lift/resistance to prevent excess leeway due to their enormous sail plans and the fact that they essentially are always going upwind! These boats sail at apparent wind angles downwind that are only about 10 degrees more than upwind! Downwind the sails are never really eased and the apparent wind never goes very far aft… the wind is always in your face on these boats! The apparent wind is so far forward on these boats that you always feel as if you are going upwind.
Combining both jobs, lateral resistance and lifting the boat into one board simplifies the boat but complicates the parts. Both teams are playing with variations of “J” or “L” boards, constant arc boards or even crazy looking “S” boards. Each shape has its slight advantages and disadvantages. They are also playing with different foil section shapes, which can produce better results at different speeds.
Racing sailors are always looking for the optimum combination of maximum lift for minimum drag. Both America’s Cup teams can raise and lower the boards to vary the surface area. They can seek more advantage by jibing them (changing angle of attack relative to the boat) and also rocking them fore and aft. Doing this, however, requires complex hull and board casing construction.
The buildup for the America’s Cup is a time for research and development, design and testing. Each team will have a matrix of foil combinations optimized for forecast wind and sea conditions. Their racing arsenal is much larger than that needed for cruising and performance/cruising multihulls to sail fast, comfortably and safely across a range of conditions.
The Morrelli & Melvin team is currently including curved lifting hydrofoils on our new Nacra F20 Carbon design and curved lifting hydrofoils will be appearing shortly on other new and exciting toys we are working on. We’re participating in BMW ORACLE’s America’s Cup developments and conscientiously incorporating design enhancements into our recreational and commercial power and sailboat designs.
Hands-On innovation at Morrelli & Melvin
November 4, 2009
A common attribute among designers and engineers at Morrelli & Melvin is the ability to build what they design. We believe that the hands-on experience enables our team to not only design products that can be built efficiently and economically, but also leads to innovation in materials and construction methods.
Gino Morrelli started out working on racing cars and boats in his family’s back yard as a teenager. He built his first boat with his dad and brother, a 33-foot Crowther trimaran in high school. Soon after he started his first company, Climax Catamarans, designing and building 18-square meter cats. He has been entrenched in onshore and offshore race-boat construction efforts since the early 80’s, managing and participating in the construction of 60’ ocean racing catamarans, Formula 40’s, the 1988 Stars & Stripes America’s Cup catamaran and many racing beach catamarans. Today he manages the Product Development side of our business where he helps bridge the gap between design engineering and our customers’ production lines. His many years of experience in racing, design, as well as on the shop floor, help us design boats that are beautiful, perform well, and are practical and economical to construct.
Pete Melvin has been creating innovative vehicles since his youth. Not discouraged when the boat he built as a 6-year old did not float, he rebounded and built a fast motorized skateboard by the time he was 10. Pete and his father designed and built several Optimist dinghies and then formed a company to build them. They used Nomex honeycomb and carbon fiber long before these materials gained acceptance in the marine industry. Pete has always designed, built, rigged, and prepared his own race boats, creating many innovations along the way and gaining valuable hands-on experience. He recently designed and built an innovative electric motorcycle that goes 50 miles on a single charge at up to 60 mph. His motorcycle is a test bed for lithium battery and electric propulsion systems that are increasingly finding their way onto M&M’s commercial, military, and pleasure boat designs.
Look what we’re working on!
October 23, 2009
Huntington Beach, CA (October 24, 2009) – Riding a wave of success with their Nacra F18 catamaran design, Morrelli & Melvin collaborated with Nacra’s design team to introduce the latest addition to the Nacra range of high performance racing catamarans. After 18 months of controlled testing of beams, rigs, hulls and foils, the Nacra F20 Carbon performance racing catamaran has been launched.
Peter Vink, the head of Nacra’s design team, proudly introduced the new boat and stated, “We took all the best features and characteristics of our current F18 Infusion, which has won the last two F18 Worlds, and applied them to the new boat. The F20 Carbon builds on the proven rudder system, mast extrusion and beams of the F18.”
Excited with the recent surge of interest in multihulls and the elegant packaging of so many design breakthroughs in the Nacra F20, Morrelli & Melvin’s co-founder and avid F18 racer, Pete Melvin, commented, “The hull shape we drew for the new Nacra F20 catamaran derives it’s bloodlines from a long line of successful multihull designs such as the Nacra Infusion. It also benefits from evolutionary improvements garnered from our involvement with A Class catamarans, ocean racing multihulls, and the current America’s Cup.”
The list of F20 design highlights Melvin referred to is long and includes an optimized hull shape that benefits from a symbiotic relationship with the curved lifting foils, spray drag reduction that incorporates hard “release edges” to reduce wetted area, enhanced recovery from nose-dives promoted by the specially contoured foredeck, and advanced volume 
distribution that takes advantage of wave-piercing technology while enhancing longitudinal stability.
These design developments add performance by improving speed and by making the boat easier to sail fast. Both elite sailors and club racers will appreciate the enhancements to this new cat.
Production is eminent and the first boats will be delivered during the first quarter of 2010.
Leopard 38 Launch Party – Thu, Oct 8. Annapolis.
September 23, 2009
Leopard Catamarans is hosting a launch party for the all-new Leopard 38, making her worldwide debut at the Annapolis Boat Show. The event will take place on Thursday, October 8 at the Leopard exhibit from 5:30-6:00 pm. Come meet the Leopard team, enjoy some refreshments, and tour the new Leopard 38. Designer Gino Morrelli will also be in attendance to explain the design and technical aspects of this exciting new model.
Please reply to this email or send a note to slong@tuimarine.com to RSVP. We look forward to seeing you!
Please note, immediately after the Leopard 38 launch will be the annual Leopard Catamarans Owner’s Party and we invite you to stick around and mingle with our owners.
Morrelli & Melvin designed and engineered the Leopard 38 catamaran in collaboration with Moorings and boat builders Robertson and Caine (South Africa). The Leopard 38 is one of the newest vacation charters to be launched and is among a number of power and sail catamarans developed by Morrelli & Melvin for Moorings.
For more information on the Moorings vacation charters
http://www.moorings.com/
More information on the boat builders, Robertson and Caine (South Africa)
http://www.robertsonandcaine.com/
James and Pete Melvin at the Top of the F18 Game
September 12, 2009
Crew James Melvin and Skipper Pete Melvin took 4th in a field of 28 Formula 18 catamarans at the North American Championships.
Pete and James scored amongst the top F18 sailors in the world during 18 races held over 5 days. The team was racing on their NACRA F18 “Infusion” designed by Morrelli & Melvin Design & Engineering and built by NACRA US, Santa Ana, California. In fact, the 1st place, 2nd place and 4th place boats were all the same NACRA / Morrelli & Melvin-designed boat. This NACRA F18 design is not only popular with the top sailors in the world, but the boat consistently delivers the competitive edge in national and international racing.
Top four teams and results:
Rank Class Nat SailNo HelmName CrewName
1st F-18 NED 1202 Gunnar Larsen Jeroen van Leeuwen
2nd F-18 NED 3 Coen de Koning Thijs Visser
3rd F-18 USA 91 Greg Thomas Jacques Bernier
4th F-18 USA 1143 Pete Melvin James Melvin
The Formula 18 North American Championship Regatta was hosted at Alamitos Bay Yacht Club in Long Beach, California from September 8 to September 12, 2009. For more information on the boat or the F18 class see:
Morrelli & Melvin Design & Engineering F18
http://www.morrellimelvin.com/
North American Formula 18 Catamaran Class
http://naf18.com/
Pete Melvin on America’s Cup Wave Piercers
August 7, 2009
Martin from Catamaran Racing, News & Design in Argentina compares and discusses the similarities and differences between Morrelli & Melvin’s hulls and the “wave piercing” bows on the America’s Cup yachts.
For the full article see http://catsailingnews.blogspot.com/2009/07/pete-melvin-on-ac-wave-piercers.html
38 Feet of Great Vacation Sailing is Launched
July 24, 2009
Sunsail celebrated the launch of the new Sunsail 384 catamaran from the Robertson and Caine factory in Cape Town, South Africa the week of July 14, 2009. The first yacht in a major charter fleet to feature solar panels, over thirty of the new catamarans are heading for Sunsail destinations across Asia and the Caribbean this fall and the Mediterranean next spring. Sunsail’s total fleet purchase plan for 2010 is over 140 new yachts, demonstrating confidence in customer demand and in line with Sunsail’s strategy of continued growth with an exceptional fleet.
The Sunsail 384 has been exclusively produced for Sunsail, with the design completed by performance multihull architects Morrelli & Melvin Design & Engineering, Inc. This catamaran is a market leader, designed for high performance with a generous sail plan, yet is also highly practical and easy to sail, making it an ideal entry level catamaran.
Bright, comfortable interior
Morrelli & Melvin design a wide range of racing, cruising, and commercial yachts. Our designs have won the America’s Cup, numerous World and Continental championships, Round the World and Transatlantic records, and multiple industry awards.
Look for details and a review of this new charter yacht in upcoming issues of Yacht World Magazine
And, find out more about Robertson and Caine and the production luxury boats they build at www.robertsonandcaine.com .
SunSail’s full announcement is available at www.sunsail.com/media/press-releases/
ABOUT SUNSAIL
Sunsail celebrates its 35th anniversary this year, offering a wide choice of sailing vacations for all skill levels, with over 900 yachts in 28 locations worldwide. In addition to bareboat and skippered yacht charter, Sunsail provides fun flotillas, sailing school courses, beach club resorts, corporate and incentive team building events.
Stable, easy to sail charter
Sunsail was founded in 1974 and is owned by leisure travel group TUI Travel PLC, a FTSE 100 leading international leisure travel group. Sunsail’s Gold LEED certified headquarters is located at 93 North Park Place Boulevard, Clearwater, FL. For yacht sales information, call 1-800-817-0807. For yacht charters and sailing vacations, visit www.sunsail.com, or call 1-800-772-3500.
NACRA Infusion Formula 18 wins World Championship
July 21, 2009
Photo used with permission from Pierrick Contin
Coen De Koning and Thijs Visser (NED) won their second consecutive Formula 18 catamaran World Championships sailing a Morrelli & Melvin-designed NACRA Infusion Formula 18 catamaran. The Royal Belgian Sailing Club – Beachclub Duinbergen was the host of the 180 teams from over 15 countries including Australia, Argentina, the USA, Canada and several European countries.
De Koning and Visser had their work cut out for them. They won the nine-race series on countback to Rob Wilson and Marcus Lynch (GBR).
The Formula 18 is currently one of the most successful one-design classes worldwide. The Formula 18 is a “box rule” development class, which specifies basic dimensions and weights and invites designers to create unique hull shapes, daggerboard and rudder designs, and rotating wing mast shapes. Over 30% of the boats in the world championship fleet were the Morrelli & Melvin-designed NACRA Infusion F 18, which was by far the largest representation of any design.
The NACRA Infusion design has been very successful since debuting in 2006, winning two World Championships and many continental championships. NACRA has sold over 400 Infusions to date. With the Infusion winning major regattas such as Kiel Week, Texel Sailing Week and the Worlds, Peter Vink, one of the founders of NACRA Europe stated, “After sailing the Infusion for four years and seeing all the new F18 designs, I would not change a thing.”
The results are speaking for themselves. This latest World Championship is yet another success for leading multihull design experts, Morrelli & Melvin Design & Engineering, Inc. Our designs have won the America’s Cup, over ten ISAF World Championships and dozens of continental championships. Morrelli & Melvin designs have also set ‘Round the World and Transatlantic records.
Morrelli & Melvin managed the tooling design and construction of the NACRA F 18 prototypes and trained the Performance Sailing staff for the production of this World Championship-winning design. Morrelli & Melvin is committed to creating and assisting builders in bringing trendsetting designs to markets around the world.
Picture used with permission. Copyright Pierrick Contin. PierrickContin.fr
Morrelli & Melvin Design & Engineering, Inc. is one of the world’s foremost designers of multihull sail and powerboats for private, charter and commercial uses. In business for over 16 years, Morrelli & Melvin have won numerous industry design and innovation awards, the America’s Cup, World and Continental Championships and broken dozens of World records.
Sailing Scuttlebutt researches the controversial America’s Cup rules. In the article, Pete Melvin of Morrelli & Melvin Design & Engineering, explains the details of hydraulics, equipment weight and the benefits to racing with “stored power”. For the original article see:
