THE BENCHMARK IN SAILMAKING
3Di is North Sails’ flagship thin ply sail technology, and unquestionably the most developed sail on the water. Instead of film or woven cloth, each sail is built from ultra-thin spread filament tapes, every one placed precisely where the sail’s loads run, then molded in one piece to the shape its designer intended. The result is a sail that flies its optimal shape across a wider range of conditions, and keeps that shape for the long haul, with no Mylar to delaminate. For any sailor who wants sails that perform for years, not seasons, 3Di is the one to invest in.
WHAT IS 3Di THIN PLY TECHNOLOGY?
Thin ply means building a sail from many ultra-thin layers of spread filament instead of a few thick ones or a laminated film. More, thinner layers allow sail designers to place fiber exactly where the loads run. The process of creating thin ply tapes removes twist from the fibers, and they are laid into the sail with no crimp – meaning that a fiber used in a 3Di sail will inherently have less stretch than the same fiber used in other sail materials. Critically, because all the fibers are bonded to each other, the structure is locked together and doesn't rely on Mylar to try to hold the fibers in place.
Thin ply means building a sail from many ultra-thin layers of spread filament instead of a few thick ones or a laminated film. More, thinner layers allow sail designers to place fiber exactly where the loads run. The process of creating thin ply tapes removes twist from the fibers, and they are laid into the sail with no crimp – meaning that a fiber used in a 3Di sail will inherently have less stretch than the same fiber used in other sail materials. Critically, because all the fibers are bonded to each other, the structure is locked together and doesn't rely on Mylar to try to hold the fibers in place.
LONGEST-LASTING
A streamlined sail shape delivers less drag, more drive, and greater effectiveness across a wider wind range. Because 3Di holds its designed shape in gusts instead of getting deeper, the boat heels less and stays in control.
North Sails designers pair our bespoke computer software and analytics with thin plies molded full size in 3D to precisely match ideal aerodynamic shapes to all types of boats. The smooth, one-piece sails are more durable and resistant to stretch. Because the sail is designed and molded in 3 dimensions, with the fibers carefully aligned to the flying shape, the effective lifespan of a 3Di thin ply sail is considerably longer than the competition.
A streamlined sail shape delivers less drag, more drive, and greater effectiveness across a wider wind range. Because 3Di holds its designed shape in gusts instead of getting deeper, the boat heels less and stays in control.
North Sails designers pair our bespoke computer software and analytics with thin plies molded full size in 3D to precisely match ideal aerodynamic shapes to all types of boats. The smooth, one-piece sails are more durable and resistant to stretch. Because the sail is designed and molded in 3 dimensions, with the fibers carefully aligned to the flying shape, the effective lifespan of a 3Di thin ply sail is considerably longer than the competition.
AERO-OPTIMIZED
A streamlined sail shape delivers less drag, more drive, and greater effectiveness across a wider wind range. Because 3Di holds its designed shape in gusts instead of getting deeper, the boat heels less and stays in control.
North Sails designers pair our bespoke computer software and analytics with thin plies molded full size in 3D to precisely match ideal aerodynamic shapes to all types of boats. The smooth, one-piece sails are more durable and resistant to stretch. The effective lifespan of a 3Di thin ply sail is considerably longer than the competition.
A streamlined sail shape delivers less drag, more drive, and greater effectiveness across a wider wind range. Because 3Di holds its designed shape in gusts instead of getting deeper, the boat heels less and stays in control.
North Sails designers pair our bespoke computer software and analytics with thin plies molded full size in 3D to precisely match ideal aerodynamic shapes to all types of boats. The smooth, one-piece sails are more durable and resistant to stretch. The effective lifespan of a 3Di thin ply sail is considerably longer than the competition.
PRECISION-BUILT
Thin ply means every ounce works.
Filaments less than the width of a human hair are placed exactly where the loads run. Each 3Di sail starts as a load map from North’s design software, which sets how many plies go where, in which direction, and with which fibers: polyester, aramid, Ultra PE or carbon, blended for how you sail. The tapes are then laid to that map and molded in one piece, so a headsail and a main on the same boat are each built for the loads they carry.
Thin ply means every ounce works.
Filaments less than the width of a human hair are placed exactly where the loads run. Each 3Di sail starts as a load map from North’s design software, which sets how many plies go where, in which direction, and with which fibers: polyester, aramid, Ultra PE or carbon, blended for how you sail. The tapes are then laid to that map and molded in one piece, so a headsail and a main on the same boat are each built for the loads they carry.
17 YEARS ON THE WATER
In production since 2009, and refined by sailors and designers every season since.
53,000+ SAILS
Delivered to every kind of boat, from club racers and cruisers to superyachts.
NEARLY 3 MILLION M²
Every square metre adds to what makes 3Di the most developed thin ply sail.
100% OF THE AMERICA’S CUP
3Di has been on every AC boat since 2013, and every 38th Cup team has chosen it.
RECORD SETTING
Powering records inshore and offshore, from round-the-buoys to round-the-world
3Di TECHNOLOGY
INSIDE 3Di
HIGH-RES SAIL STRUCTURE
A 3Di sail’s structure is composed of multiple hair-thin spread filament plies applied in precise, hi-resolution vectors (length and direction) to optimize strength-to-weight ratio strain and compressive loads. 3Di sails are 70% fiber, 30% resin, and zero dead weight.
HELIX
You want 3Di for your structured luff sails. Exclusive to North Sails, Helix Headsails utilize 3Di composite structures to radically improve camber control. Forward-projecting Helix Code and Flying Sails improve aerodynamics while reducing the load on your boat and mast.
INTEGRATED REINFORCEMENTS & FINISHING
The 3Di membrane includes an essential sail structure and fully integrated reinforcement details like batten pockets, corner reinforcements, and reef structures. By integrating reinforcements into the 3Di structure, North's designers and aero engineers improve durability and load handling while saving weight.
HIGH-RES SAIL STRUCTURE
A 3Di sail’s structure is composed of multiple hair-thin spread filament plies applied in precise, hi-resolution vectors (length and direction) to optimize strength-to-weight ratio strain and compressive loads. 3Di sails are 70% fiber, 30% resin, and zero dead weight.
HELIX
You want 3Di for your structured luff sails. Exclusive to North Sails, Helix Headsails utilize 3Di composite structures to radically improve camber control. Forward-projecting Helix Code and Flying Sails improve aerodynamics while reducing the load on your boat and mast.
INTEGRATED REINFORCEMENTS & FINISHING
The 3Di membrane includes an essential sail structure and fully integrated reinforcement details like batten pockets, corner reinforcements, and reef structures. By integrating reinforcements into the 3Di structure, North's designers and aero engineers improve durability and load handling while saving weight.
EXPLORE 3Di THIN PLY TECHNOLOGY
FREQUENTLY ASKED QUESTIONS
A: Most sails are built from woven cloth or laminated film, and both rely on yarns: bundles of fiber. Under load, those bundles straighten and settle before the fiber itself takes the strain, and that's stretch. Thin ply removes it. The same high-performance fibers are spread out into ultra-thin plies of perfectly straight, flat filaments, each finer than a human hair, so they carry load the moment it's applied. Those plies are then laid exactly along the sail's load paths, putting material only where it's needed. The result is less stretch, lower weight and a sail that holds its shape longer. Thin ply is the foundation of North's most advanced sail technology, starting with 3Di.
A: A 3Di sail is built and cured as one piece in its finished three-dimensional shape. With no Mylar film, which behaves differently from the fiber it's bonded to, everything works as one. Less stretch, less weight, strong resistance to UV, chafe and flex, and a shape that lasts.
A: Spread filament technology. A filament is fiber in its purest form: a single, continuous strand. Conventional sailcloth bundles thousands of filaments together into yarn. We do the opposite, spreading them flat and side by side into thin ply tapes coated in thermoset resin. Most 3Di tapes blend multiple fibers, and North has a library of over 50 blends, so we can pair the strength of one fiber with the flex resistance of another. That lets us fine-tune the composition within each sail, balancing performance, durability and weight for how it will be sailed. The result is a sail that's exceptionally strong, yet remarkably light.
MATERIAL GUIDE
EXPLORE 3Di USE GROUPS
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CUSTOMER TESTIMONIALS
3Di is an amazing product for racing sails, truly the best technology available. North 3Di sails are extremely strong and built with precise, refined sail shapes. I recommend North Sails and 3Di because they are the best sails, created by the best designers.
PIERLUIGI DE FELICE
GRAND PRIX SAIL TRIMMER
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CUSTOMER TESTIMONIALS
We chose North 3Di because a versatile inventory and longevity were crucial factors for Miss Shell. Since her launch in 2022,Miss Shell has sailed more than 15,000 miles! The 3Di sails have lived up to their promise with only two routine maintenance appointments. Whether we're crossing the Atlantic, exploring the Med, or sailing in New England, North 3Di is our choice and recommendation to other sailors.
ERIC LEINER
OWNER, MISS SHELL
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CUSTOMER TESTIMONIALS
We sail really hard, so it´s important to have strong sails; reliable but good performance. The sails are what makes the boat go fast.
CHARLES DALIN
IMOCA SKIPPER
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