Gennaker Kabel
Gennaker-Torsionskabel haben – bezogen auf die gleiche Länge – einen größeren Durchmesser als Bottom-up-Furlingkabel, um die zusätzlichen Torsionslasten beim Top-down-Furling aufzunehmen. Das liegt daran, dass die Torsion über die gesamte Kabellänge übertragen werden muss – von der Trommel bis zum Kopf des Segels, wo das Einrollen beginnt.
Gennaker cables, more accurately described as gennaker torsion cables, are a specialised component used in top-down furling systems for asymmetric sails. Their primary role is to transmit rotational torque from the furling drum to the head of the sail, enabling controlled furling while the sail luff remains free-flying. Correct selection and specification of gennaker cables is critical for reliable furling behaviour, predictable sail handling, and long-term system durability.
Unlike Code Zero or straight-luff sails, gennakers are not supported by the torsion cable along the luff. As a result, gennaker torsion cables are designed specifically for torque transmission, not for providing luff support or forestay-like structural stiffness. This difference drives key design and construction choices in fibre selection, cable diameter, and termination method.
Top-Down Furling Mechanics and the Role of Gennaker Torsion Cables
In a top-down furling system, the furling drum is attached at the tack of the sail via a strop or soft connection, allowing the tack to rotate freely. The head of the sail is connected to a swivel that is mechanically linked to the torsion cable. When the drum is rotated, torque is introduced into the cable and transmitted upwards to the head swivel.
Furling begins at the head of the sail and progresses downward toward the tack. This head-initiated furling action is essential for asymmetric sails, as it allows the sail to roll cleanly around its own body rather than relying on a fixed luff.
For this system to function correctly, the gennaker torsion cable must exhibit high torsional stiffness with minimal angular lag between drum rotation and head response. Any delay or torsional softness can result in uneven furling, partial wraps, or difficulty furling the sail under load, particularly as sail size and apparent wind increase.
Armare Gennaker Torsion Cables – Construction Principles
Armare gennaker cables are engineered specifically for top-down furling applications, using unidirectional high-modulus fibre cores optimised for torque transmission. The fibres are aligned parallel to the load axis to minimise constructional stretch and ensure consistent behaviour under dynamic loads.
Common fibre choices include Dyneema SK78 and Dyneema SK99, selected for their high strength-to-weight ratio, low creep characteristics, and good fatigue resistance. The core is then stabilised using multiple braided cover layers. These braided layers play a critical role in torsional performance by resisting fibre rotation and maintaining core integrity under repeated torque cycles.
Key construction features of Armare gennaker torsion cables include:
- Unidirectional fibre cores for low elongation
- Multiple braided covers to increase torsional stiffness
- Compact diameters to reduce windage and weight
- UV- and abrasion-resistant outer layers
- Custom manufacture to exact finished length
This construction approach allows Armare to maximise torsional efficiency without unnecessarily increasing cable diameter, which is particularly important for performance-oriented installations.
Integrated Terminations and Hardware Compatibility
Unlike torsion ropes supplied in continuous lengths, gennaker torsion cables are typically custom built with integrated terminations. Armare cables are manufactured to finished length with end fittings installed during the build process rather than added later via clamping or splicing.
Typical termination options include:
- Soft or hard thimbles built into the cable structure
- Eye-to-eye or eye-to-swivel configurations
- End fittings sized to match specific furling drums and swivels
This integrated approach reduces bulk at the cable ends, improves load alignment, and removes dependence on external mechanical clamps. It is particularly beneficial for gennaker sails with narrow head patches or compact luff tapes, where space and articulation are limited.
Applications for Gennaker Cables
Gennaker torsion cables are used across a wide range of sailing applications wherever top-down furling of asymmetric sails is required.
Cruising Gennakers
For cruising yachts, gennaker cables provide predictable furling behaviour and simplified sail handling. Reliable top-down furling is especially valuable for short-handed crews, where the ability to furl the sail cleanly under load reduces deck work and increases safety.
Performance and Racing Gennakers
In performance and racing environments, rapid torsional response is essential. Armare gennaker cables are commonly specified where fast hoists, controlled drops, and clean furling during manoeuvres are required, with minimal impact on sail shape or windage.
Offshore and Shorthanded Sailing
Offshore sailing places additional demands on furling systems due to variable loads and sea states. Correctly specified gennaker torsion cables help ensure consistent furling behaviour, reducing the risk of partial furling or uncontrolled sail deployment.
| Sail Area (m²) | Typical Boat Size (LOA) | Typical Cable Ø (mm) | Typical Application |
|---|---|---|---|
| 40–80 | 30–36 ft | 6–7 mm | Cruising gennaker |
| 80–120 | 36–44 ft | 8–9 mm | Performance cruising |
| 120–180 | 44–52 ft | 10–11 mm | Offshore / race |
| 180+ | 52+ ft | 12 mm + | Maxi / heavy-duty |
Selecting the Correct Gennaker Torsion Cable
Choosing the correct gennaker cable involves more than matching a breaking load. Key parameters to consider include:
- Sail area and luff length
- Expected working and peak loads
- Required torsional stiffness for effective top-down furling
- Compatibility with furling drum and head swivel geometry
- Acceptable cable diameter relative to sail construction
Overspecifying diameter can increase windage and weight aloft, while underspecifying torsional stiffness may compromise furling performance. Armare’s manufacturing approach allows cable specifications to be tailored closely to the sail and furling system rather than relying on generic size categories.
Gennaker Torsion Cables vs Code Zero Cables
While both systems use torsional elements, gennaker torsion cables and Code Zero torsion cables serve fundamentally different purposes.
Gennaker torsion cables are used for top-down furling of free-flying asymmetric sails
Code Zero torsion cables are used for bottom-up furling of straight-luff sails that rely on luff support
Understanding this distinction is essential when specifying furling components, as the load cases, stiffness requirements, and construction methods differ significantly.
Summary on Gennaker Cables
Gennaker cables, also referred to as gennaker torsion cables, are a critical component in top-down furling systems for asymmetric sails. Designed specifically for torque transmission rather than luff support, they require high torsional stiffness, low elongation, and compact diameters.
Armare gennaker torsion cables combine high-modulus fibres, purpose-built construction, and integrated terminations to deliver reliable furling performance across cruising, racing, and offshore applications. Correct specification ensures predictable sail handling, improved safety, and long-term system reliability.
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