Elvström Sails is expanding its range with Xylo, a composite sail technology for regatta and cruising sailors. The Danish sailmaker uses Technora fibres in combination with a spread filament layout. Filaments are fibres that are only about half as thick as human hair and are used in various bundle thicknesses and shapes. The system is available in two versions: Xylo Core for regatta sailors and Xylo Force for demanding long-distance sailing. The Force version has an additional taffeta reinforcement for longer durability. Both versions utilise the same production processes as the manufacturer's Epex membrane sails.
Technora instead of carbon
The sailmakers use Technora fibres from the Aramid family. According to the manufacturer, these fibres are more resistant to cyclic bending than carbon. The material expands less under continuous load, which stabilises the shape over longer periods of time. Carbon breaks more quickly under repeated bending loads, while Technora remains flexible, says Elvström. Technora - a high-performance para-aramid fibre - is closer to an ideal choice than other high-modulus fibres such as Kevlar, PBO, Dyneema or carbon. Technora combines a special combination of many favourable properties:
- Exceptionally high tensile strength.
- Very good fatigue and abrasion resistance; the fibre retains its strength even after repeated bending and abrasion.
- Resistant to acids, alkalis and organic solvents and insensitive to vapour or salt water.
- Unlike other aramids, Technora absorbs very little moisture - less than two per cent - which makes it more stable in humid environments.
- Although Technora is somewhat sensitive to prolonged UV exposure, Elvström Sails claims to have found a solution.
- The fibre does not melt; with a decomposition threshold of 500 degrees Celsius, it offers very high thermal stability.
- The fibres are processed as flat filaments, which covers the entire sail surface. This means that there are no fibre-free gaps in the structure.
Longevity vs. performance
Design of the composite structure
The spread filament layout enables fibre alignment in all directions. The filaments can be positioned precisely along the load paths in the sail. A cross-linking polyurethane-based thermoset adhesive bonds the fibres. This adhesive forms a rigid molecular structure during curing. Unlike thermoplastic adhesives, it does not soften or melt when exposed to heat. Processing takes place under high vacuum, after which the material is laminated. Elvström utilises the patented processes from Epex production for this.
Like other membranes, the cloth is therefore created by the sailmaker and does not come from an external manufacturer. Elvstrøm manufactures the sails two-dimensionally in large panels, the profiling is created conventionally by broadseeming, i.e. by darting. For the mainsail of a 40-footer, for example, four panels are produced consisting of five layers of filament.
Xylo Force for cruising sailors
The Force version is aimed at cruisers with high durability requirements. An additional taffeta protects the filaments from mechanical wear. The weight is the same as the Epex Double Taffeta, but the dimensional stability should be higher. The sailmakers produce both conventional sails and furling mainsails for in-mast furling systems from the new material. The complete fibre coverage by wide filaments eliminates weak points in the structure.
Xylo Force offers cruising sailors an alternative to Epex Double Taffeta. The higher dimensional stability brings advantages for longer trips in changing conditions. The sail retains its profile better, which stabilises performance over its service life. The taffeta reinforcement increases robustness in everyday use. Cheaper laminates are sufficient for weekend sailors with moderate requirements. Ambitious cruisers with high annual mileage benefit from the longevity. The investment is amortised over the longer service life.
Xylo Core for regatta sailors
Core dispenses with taffeta and relies exclusively on filaments. This reduces the weight and sharpens the racing profile. The weight is on a par with Epex Film-Film. Olympic champion Jesper Bank tested early versions three years ago. Since then, the sails have undergone optimisation in terms of structure and component selection.
360-degree stability in practice
The fibre layout covers all load directions. If the load shifts in the sail, the shape and profile remain stable. The wide filaments distribute the forces evenly over the entire surface. This prevents punctual overloading and localised stretching. Dimensional stability is maintained even in changing wind conditions. The system is said to be particularly advantageous for longer strokes when the sail is permanently under load.
Comparison with other technologies
Elvström now covers four main technologies: woven polyester fabrics, laminates, Epex membrane sails and Xylo composite. Woven cloths stretch more and lose their shape more quickly. Laminates offer more stability, but do not achieve the values of composite sails. Epex membrane sails lie between laminates and composites. Xylo is said to provide the highest dimensional stability at a comparable weight. Technora fibres cost more than standard polyester, but retain their properties for longer.
Tests with Dragonfly trimarans
Quorning Boats from Denmark equips its Dragonfly trimarans with Xylo sails. The two companies have been working together for over 40 years. Trimarans place special demands on sails, as they reach higher speeds than monohulls. The sails must remain stable under changing loads. The Dragonfly fleet serves as a testing ground for new developments. Experience gained from this use is incorporated into further optimisations.
Maintenance and care
Composite sails require careful handling. The sails should be stored in a dry place to protect the adhesive joints. Avoid kinks when setting and retrieving. The Taffeta reinforcement on Force protects against abrasion on shrouds and spreaders. Damage to the filaments is more difficult to repair than with woven sails. Regular inspections reveal wear at an early stage. UV radiation affects all sail materials, but Technora shows good UV resistance.
Availability and production
Production takes place at the main plant in Aabenraa, Denmark. Xylo Force is already available, Xylo Core can be ordered. The sailmaker has invested in new production facilities for composite technology. The manufacturer does not disclose prices publicly, but they are again higher than Epex sails, the previous premium line. The delivery time depends on the order situation and sail size. Interested parties should plan several months in advance.
Classification for cruisers
Xylo Force offers cruising sailors an alternative to Epex Double Taffeta. The higher dimensional stability brings advantages for longer trips in changing conditions. The sail retains its profile better, which stabilises performance over its service life. The taffeta reinforcement increases robustness in everyday use. Cheaper laminates are sufficient for weekend sailors with moderate requirements. Ambitious cruisers with high annual mileage benefit from the longevity. The investment is amortised over the longer service life.
More on the subject of sails
Fridtjof Gunkel
Deputy Chief Editor YACHT
