!!!...DesmA...!!!

Rig and sail modeling


Desman creates a complete rig/sail model in a three-dimensional environment. In Desman, North designers can specify mast size, rigging position, rigging attachment points at the deck and trimming locations. The modeled sail/rig system incorporates the mechanical properties of the spars, standing rigging, running rigging and sails in terms of moments of inertia, sail and spar surface area, materials stiffness and resistance to stretch. Later in the process, Membrain (described later) uses the Desman model to determine deformation under load for the sail and every piece of standing and running rigging, right down to stretch in the sheets and halyards.

Modeling genoa staysail and A2 spinnaker

Richel / Pugh 82 Highland Fling

Right: Volvo 70 reaching simulation.

Left : Wild Oats model for rig tune. 

How is 3DL Made.....?

sails begins with a three dimensional CAD/CAE design file created by a North Sails sail designer. North's proprietary design software creates a custom "mold" file for each individual sail. Because a 3DL sail stretches less than competing 2D paneled or “string” sail for a given amount of yarn, North designers can more accurately define the desired "flying shape" because the computer molded shape is that much closer to the resultant flying shape.

sophisticated computer program reads the design file, then instructs an articulating mold to assume the designed shape. Shown here is the underside of a 3DL mold with actuators controlled by a highly sophisticated computer program.

After a base layer of Mylar film (made from Mylar sections joined together with modest shaping to lie reasonably smoothly over the 3D surface of the mold) is draped over the mold and tensioned, a 6-axis fiber head suspended from a computer controlled overhead gantry then applies structural yarn onto the surface of the base film, precisely following the 3D curve of the mold surface. The fiber head "draws" a pattern in yarn that matches anticipated loads in the sail. All structural yarns are applied under uniform tension and adhere to the surface of the film to ensure they remain in place prior to being locked by the lamination.

Once the yarns are laid, a second film is positioned on top of the base film and yarn, tensioned, and then covered with a large vacuum bag that compresses the laminate at approximately 1,800 pounds per square foot. This second film contains a secondary mapping of yarns to handle incedental loads off the primary load lines.

The gantry head is then removed and replaced with a carbon element heat “blanket” that cures the pressurized laminate by imparting a carefully controlled amount of heat through the laminate. This causes the laminate to conform tightly to the mold in a manner similar to a shrink-wrapping process. After curing, the sail is allowed to cure further for a full five days prior to shipping and/or finishing.

When the laminate has cured, corner reinforcements, bolt ropes, batten pockets and protective patches are applied by experienced sailmakers. Because of the inherent material efficiency of the 3DL manufacturing process, a finished 3DL sail can be up to 20% lighter than a conventional paneled or a “string” sail of equivalent stretch. Or, it has a wider wind range (larger sweet spot) for a given weight.

..How the modules work togetheR..

Flowchart of software suite tool interaction

..Desing ResourceS..

No other sailmaker can match the experience and resources of the North design team...

• 65 sail designers representing over 350 years of combined experience

• 5 full-time software engineers dedicated purely to the development of our sail design software

• 28 years of leadership in computerized sail design.

A legacy of leadership...

• North was the first sailmaker to perform computerized structural analysis in sails.

• North was the first sailmaker to analyze upwind sail shapes with computer air flow simulations

• North was the first sailmaker to implement 3-dimensional computer modeling.

• North was the first sailmaker to develop and use an integrated suite of sail design software

• North was the first sailmaker to develop and use computer aided laser sail panel cutting, dramatically improving accuracy and consistency in sail production.

• North was the first sailmaker to test downwind sails using a “twisted flow” wind tunnel, which simulates differences in apparent wind speed and apparent wind angle between deck level and the upper part of the rig.

• North was the first sailmaker to develop an accurate wind flow modeling software for analysis of downwind sails. Virtual Wind Tunnel accurately analyzes stress, strain and wind flow at 100% scale.

!!!...History of 3DL...!!!

North SailsIn 1990, Luc Dubois and J.P. Baudet, saw the future of sailmaking from a different perspective. In a back room of the North Sails loft in Milford, CT, far from curious eyes, Baudet spent his days in a hang-gliding harness, floating over a wooden mold, like some high-tech Peter Pan. By hand Baudet was gluing Kevlar yarns under tension to a sheet of Mylar, which was draped over a three dimensional wooden plug. The goal was to form a perfectly shaped J/24 headsail in one continuous 3-D piece, rather than with myriad seams - the traditional method of shaping sails. Some 4500 meters of Kevlar yarn was painstakingly oriented to match the loads in the sail. Baudet worked hard to lay them down under equal tension, so as to lock in the shape.

North SailsNext , a second piece of Mylar was placed over the top, completing the "sandwich." The sail was vacuum-bagged together, compressing the two pieces of Mylar "bread" around the Kevlar "meat." Finally, the glue was set off by the application of heat, in this case with an ordinary iron! This sandwich construction was more boat building than sailmaking. In fact, the idea of molding sails had occurred to Baudet when studying boat building back home in Switzerland at age 17. Later, he and his friend Luc Dubois brought the idea to North, and the project was set in motion. Coincidentally, in 1980, Eckart Wagner, then president of North Sails Surf (i.e., windsurfing), had received a patent in Germany for molded sails reinforced with fibers.

By 1990, J.P. and Luc produced the J/24 genoa. The sail held its shape in strong winds and stood up to wear and tear. It was also 33% lighter than a "normal" J/24 headsail. Without seams, the sail was remarkably smooth, like glass. For North, this was the beginning of three-dimensionally laminated sails, or "3DL®."

Most modern sails achieve their three-dimensional shape through the contour of numerous panels of sailcloth sewn together in a process called broadseaming. Lowell North pioneered this process in modern sailmaking and much of North's success has stemmed from its ability to utilize this process successfully.

North Sails3DL takes this process to the next step. Instead of relying on flat cloth with curved edges, the 3DL process molds the entire sail over a three-dimensional mold.

3DL sails are fast because they are up to 20% (and sometimes more) lighter than a conventional sail, stretch less, and have a wider effective wind range (which means potentially fewer sails in your inventory). 3DL more efficiently utilizes each individual yarn because it is laid smooth and continuous - with no breaks or bending at seams - in the same shape that it is expected to take when sailing.

3DL sails are currently built in Minden, Nevada, in the largest and most sophisticated sailmaking facility in the world. Programmable molds are draped with Mylar film and then a computer-controlled system applies precisely tensioned yarn over the Mylar. Additional 3DL molds have recently been put into operation in North's manufacturing facility in Sri Lanka.

The molds can be adjusted to shape sails of widely varying cambers. Sewing is limited to the corners, edges or attachment points of the sails.

It is not over-dramatizing to state that North literally bet its future on 3DL, given the sizeable investment it made and continues to make. For North and its customers, the future is now.......!

3DL Q&A... Commonly Asked Questions

How long does a 3DL sail last?

Competitive Grand Prix racing boats typically log 150-200 racing hours on an Aramid paneled mainsail. For example, Team Dennis Conner used the same 3DL® heavy mainsail throughout their entire America's Cup campaign in 2000.

In the 2003 AC campaign, many syndicates reported over 400 hours on their 3DL carbon mains. Tacking and flogging take their toll on genoas, making them last considerably less than mains. AC syndicates and high tech programs use genoas/jibs sometimes only 20 hours. (While this sounds like so little time, a typical day race would include about 1.5 hours of upwind work. That’s 13 races for that one genoa, which, depending on wind speed is only used part of the time.)

However, with proper care while the sail is in the bag, with minimizing flogging, with care to use the sail in its intended wind range and with proper flaking in the bag, 3DL genoas/jibs can be fast for seasons as opposed to hours. While no two boats are the same and sail handling is the prime determining factor in a sail's longevity, North had documented many cases where the competitive sail shape retention of a 3DL sail is close to double that of an equivalent paneled sail.

While a 3DL sail may cost a bit more initially compared to paneled sails, 3DL's superior longevity makes it a superior value in the long run. This is one of the many reasons why 100% of the Volvo and AC syndicates chose 3DL.



Other sailmakers claim they can build sails that are lighter than 3DL.
Is that true?

Any sailmaker can make a sail as light as 3DL sail, but sacrifices will be made in effective wind range and durability. Remember that 3DL is lighter for a given amount of stretch or is less stretchy for a given amount of weight for the simple reason that the continuous yarns, laid in their 3D plane on the mold load up more evenly than those same yarns in a sectioned panel sail, whether tri-radial or the so called 2-D “string” sails. Some competitors have claimed their sails to be as light as 3DL in classes where corrective weights are added to a 3DL sail to meet class-specified minimum allowable weights.


Can you recut a 3DL sail?

This is a commonly asked question by sailors who have not sailed with a 3DL sail before, as recutting is a "part of life" with paneled sails. What we tell paneled sail users is that because the 3DL process reproduces a sail design (mold) more accurately and the sail holds its shape over a broader wind range and holds its shape far longer, recutting is rarely needed. If it is necessary, a 3DL sail can be recut by your local loft using the same procedures as a standard scrim sail. Minor tears and punctures are often repaired by simply applying reinforced Mylar tape over the damaged area.


Can you adjust the shape of the sail?

Because a 3DL sail's shape is molded in as it is manufactured, some owners have asked if the shape can be adjusted easily. Outhaul, Cunningham, mast bend, headstay sag and lead positions are adjusted the very same way as with paneled sails. However, less tension is needed to achieve a similar effect.

How much lighter are 3DL sails than paneled?

Compared to a traditional paneled sail with similar stretch resistance, a 3DL sail typically weighs about 20% less.


How does the cost of a 3DL sail compare with paneled sails?

3DL initially costs more than a paneled sail, but if you consider the superior shape retention of 3DL over several seasons, 3DL turns out to be less expensive per mile of fast sailing. We have many customers enjoying their third competitive season with their 3DL sails.


Can 3DL be used for cruising sails?

Yes. North's Marathon 3DL is engineered specifically for cruising sailboats. Marathon 3DL features yarn types and layouts designed for cruising use and North TF taffeta/film bonded to both sides of the laminate for additional chafe, tear and UV protection. Additional UV inhibitors are also applied to each individual yarn as well as the adhesives that bond the laminate.

For more answers on 3DL and how it can revolutionize your sailing, call your nearest North representative today.

!!!...3D vs 2D...!!! What's the Difference......?

While the difference between the generic terms “3-dimensional” (length+width+depth) and “2-dimensional” (length+width) are relatively easy to grasp, understanding the difference between 3-dimensional and 2-dimensional sailmaking is a bit more involved.

While a sail itself has negligible “depth” (the thickness of the sailcloth or laminate from which it is made), when it is pressurized by wind it assumes a significant 3-dimensional shape... or, “flying shape.” Sail designers work hard to define the best shape for a specific sail, and the people who make the sail work VERY hard to achieve that shape on the water. It is in achieving the desired flying shape that the difference between 3D and 2D sailmaking comes into play.


2D sailmaking


The traditional method of sail construction is to stitch or glue together flat 2-dimensional segments (panels) of woven or laminated material to form the sail. Using a method called “broad seaming,” the edges of the panels are given curvature so that when the assembled sail is pressurized by wind, it will assume a specified flying shape. In essence, 2D segments have been assembled to emulate a 3D form. This is how sails have been made for hundreds of years and how all 2D sails are still made today.


3D sailmaking



A more modern method of shaping a sail is to laminate it on a full-sized 3-dimensional mold in the precise flying shape it will assume when sailing. The resulting sail will have smooth, compound curvature in all directions and sail loads will be distributed more efficiently. Only North 3D sails (3DL or 3Di) are manufactured on full-sized 3-dimensional molds using a patented process.




Following are several examples illustrating the essential difference between 3D and 2D construction...

North 3DL and 3Di sails are the only sails in the world that are manufactured 3-dimensionally (see below left). ALL other sails are manufactured 2-dimensionally (see below right). While 2D sails can be manufactured to look like a North 3D sail, only North 3D sails are molded 3-dimensionally with every structural element formed in the precise curved space it will occupy when sailing.

Another important difference between 3D and 2D sailmaking involves the unique thermo-forming process North uses in the manufacture of its 3D sails. After the lamination process is completed, vacuum pressure and heat are applied to the laminate while it is still on the mold (see below). The heat and pressure not only consolidate bonding within the laminate, they also cause the laminate to conform tightly to the mold in a manner similar to a shrink-wrapping process. This patented thermo-forming method means North 3D sail shapes are more accurate and more repeatable than shapes produced using any other sailmaking system.