Each design process starts with the measurement of the rig. The sail designers at Elvstrom Sails then use the rig data to create an exact, three- dimensional computer model.

This means the sail plan can be perfectly matched to the geometry of the rig without even the slightest bit of sail surface.

Special attention must be paid to spreader sweep and (wind-related) factors like mast bend and luff sag (backstay tension) and so precise knowledge of the different types of boat is essential.

Our designers are all active sailing buffs, fully aware of the dynamic behaviour of modern rigs and have access to a database of 3,000 types of boats.

Wind range and profile

Basically the same principle applies to any size of sail; the stronger the wind, the flatter the profile. This sees the maximum profile depth moving further and further in the direction of the leading edge (luff).

Within these parameters the sail designer can find the best configuration of the shape. The characteristic of a sail depends to a large extent on how the sail profile changes across the full length.

A very flat sail in the lower luff area will sail ”more keenly“; i.e. it will be able to sail higher on the wind and slightly faster, however it will require an experienced trimmer and a cool hand at the helm.

On the other hand, a more bulging sail in the bottom area sails slightly more softly, because the range of the optimum trim is wider.

Yarn Layout

As soon as the geometry and the basic profile are established, a model of the sail is set into the rig plan.

State of the art software is able to accurately place this raw model into the rig geometry. This immediately gives the designer a sail shape, whose characteristics can be adapted based on the customer’s wishes and requirements. This step requires an extreme amount of experience and this is why the designers at Elvstrom Sails spend many hours at the water. This is the only way that the shapes can be constantly improved!

The yarn guides are placed into these computer moulds. The trick here is to use as little material as possible and just as much as is needed.

Only the best layout will give you the best weight to stability ratio and thus the fastest sail.

The density of the yarns used is measured in dpi (dpi = denier per inch) and indicates the number of individual fibres in the yarn per inch. This value is measured at a very specific point at the stern (see sketch).

The picture 4 on the left shows the strings that bear the main loads on the sail (red); on the right you can see all the yarn guides of a high density EPEX sail. The so-called transversal strings are grey.

Clearly visible is the particularly high yarn density in the sail corners. In some cases in a super yacht sail, the thickness of the material on the sail tack may be almost 2cm.

The picture 5 above shows the finished sail profile and final layout. This computer model is sent directly to the control at EPEX-Technologies, thereby systematically eliminating any production tolerances.