Sailmaking Construction Update 2017

Technology continues to move forward in both fabrics and construction; sails that seemed exotic just a few years ago are now becoming the norm out on the water. Over the last decade there has been a major move away from paneled sails towards the “Load Path Membrane” sails in the racing market, proven performance and durability with woven Dyneema fabrics for larger cruising boats, and low stretch “crimpless” Dacron for improved performance in tri-radial cruising and racing sails.

The majority of racing sails we build today are our PowerPath membrane sails where the fibers themselves are laid out in the orientation to follow the loads in a sail rather than using individual panels to align the fibers as in a tri-radial sail. The advantages are a sail that holds its shape better, is lighter, and in most cases is less expensive than a tri-radial sail because of savings in material and labor costs.

In a membrane sail the fibers are laid throughout the sail to support the dynamic loading imposed while sailing. This matrix insures that as loads vary while sailing the designed flying shape will be maintained across the intended design range of the sail. We design each sail the same as we would any other type of paneled sail to produce an end product that is custom shaped to fit each boat and the intended range of conditions. In a paneled sail this design is then transferred to our computerized cutting system where the individual panels are cut out and then assembled. In a membrane sail the final design along with the fiber type and content we want for each sail is sent to PowerPlast in Italy for custom lamination. They return a laminated “membrane” that is three dimensionally shaped exactly to our design. The sail is then built from that membrane rather than panels cut from a roll of cloth; doing the final layout and measurement to insure it matches any necessary rules, apply all the corner reinforcements, batten pockets, leech, luff, and foot tapes, and all necessary hardware.

Recent advances in membrane technology include new membranes that are softer and take flex better, improved lamination techniques that have pretty much eliminated de-lamination, more fiber options, and a new “Filmless taffeta” construction. The Filmless membranes are made by laminating a series of fibers in different orientations with two high strength taffetas and a UV/ Mold shield on both sides. These sails are proving to be extremely durable for Offshore racing and high performance cruising sails.

On the cruising front we now are building more and more sails using the Dimension-Polyant Hydra-Net Radial fabric. This is a woven cloth utilizing a combination of Dyneema and Dacron. With nothing to crack, peel, or delaminate it is proving to be an incredibly durable fabric. With stretch numbers close to a racing laminate it has excellent shape holding and still has the durability for extended offshore cruising. Without the mylar laminate to trap moisture it is also much less likely to mildew. For large, highly load sails where both shape and durability are required this has become the fabric of choice. We have used it on both mainsails and headsails on boats between 40 feet and 80 feet, including several large multihulls that are reporting longevity of at least twice as long as sails made of cruising laminates.

For smaller boat where the low stretch of Dyneema is not needed Challenge Sailcloth has recently introduced their “crimpless” Dacron for radial sails. Sailcloth is woven with fibers going in two directions; the long direction is called the “warp” and the short direction is called the “fill”. Because of inherent way that conventional looms operate the fill yarns will be relatively straight while the warp yarns will go up and down over the fill yarns. This is called crimp, and because these yarns are not straight in the weave the fabric will have more stretch in the direction of the crimped warp yarns. If the fabric is loaded in the warp direction it will stretch more as those yarns try to straighten out. When loaded in the fill direction the fill yarns are already nearly straight and will have less stretch.

The result of this is that most Dacron sails have to be built as cross cut sails where the panels are laid out perpendicular to the leech. This configuration lines the fill yarns vertically up the leech which is the area that is most highly loaded. However a cross cut sail can never fully support the loads in a sail as well as a radial sail because while the most load may go up the leech there is still a lot of loading, especially in the corners, where the load is transmitted out into the body of the sail. In a tri-radial sail the panels radiate out of the corners and rotate up through sail in a pattern that keeps their primary yarns more closely lined up with the actual loading. Tri-radial sails were designed around using laminate fabrics where the primary yarns in the warp direction are laid out flat with little or no crimp and then laminated between two films of mylar. This allows them to have the lowest stretch in the warp direction and work perfectly in radial sails.

The Challenge fabric, aptly named “Warp Drive” overcomes this problem with new patent pending weaving and finishing technology that allows the fabric to be woven with the crimp taking place in the fill yarns while the warp yarns have nearly zero crimp. The result is the first true warp orientated Dacron that is made for making radial sails. Its primary use will be in cruising sails for boat in the 30’ to 50’ range where the customer wants the longevity of Dacron with better shape holding than you can get in a cross cut sail. For furling headsails it also much less likely to mildew than a cruising laminate will.