2. Radial cut
Radial cut constructions more closely follow the load patterns on a given sail
Radial cut sails are mostly (but not exclusively) made from laminated sailcloth – that is, any fabric consisting of two or more layers adhered together. There are perhaps dozens of products on the market, almost all of which contain three essential elements: n One or more layers of film. n Fibres (such as Kevlar, Vectran, Spectra, carbon or polyester) that are laid into the laminate to enhance the strength in a particular direction. n Taffeta (a woven fabric glued to the outside of the laminate).
Initially laminate sails were used only by racing boats, because they break down much more quickly than woven products.
However, in the last 20 years or so they’ve become increasingly popular with cruising boats as the cloth manufacturers have made styles that are more suited to that end-use.
Essentially either a single-sided or double-sided woven taffeta backing is added to the laminate, which makes it more durable than the racing counterparts. The result is a fabric well suited to performance cruising which holds its shape better than Dacron but is more durable than a race laminate.
In the photo (top right) Ian holds a single taffeta laminate in his left hand – one of the load bearing fibre scrims in the middle is visible – and a heavier more cruise oriented double taffeta cloth in his right hand.
Unlike Dacron, radial cut fabrics are much stronger in the warp direction than the fill, which means they can be used in a different way. The panels can be cut in long narrow triangles and trapezoids with the strong warp fibres aligned with the loads in the sail that radiate out from the corners.
One of the advantages of laminates is that they are much stronger for a given weight. A double taffeta cruise laminate might not be much lighter than the equivalent Dacron but it will be hugely stronger resulting in far more stable shapes and better performance.
The downside to laminates is that they’re not as durable. All things being equal, if a Dacron sail lasted eight to ten seasons then the double taffeta laminate alternative might be good for five or six. It’s not always the rule – Ian has seen laminate sails still performing at 15 years old, though this is unusual.
Until recently, radial cut sails usually meant laminates. However, the last decade has seen a range of radial hybrids enter the market such as Hydranet – a woven sailcloth with a large amount of stretch-resistant Dyneema providing additional strength mixed in with Polyester. The downside is that these hybrids are relatively expensive, but in terms of performance they are roughly equivalent to the lower end of laminates, providing superior performance to Dacron whilst retaining much of its durability. Budget-allowing, this would be a trouble-free, long-lasting option for a bluewater or retirement cruise.