4T Forte - One piece composite sails for racing & cruising

In 2007, OneSails introduced the first continuous fibre sails built without the use of resin or glue, eliminating delamination issues at a stroke. Now OneSails goes a step further, by introducing 4T FORTE™ membranes made from exclusive Multi Micro Structure (MMS™) technology (patent pending).

The 4T FORTE™ composite structure incorporates high modulus fibres such as STR Solid Stripes, a new low stretch component of MMS™ technology which eliminates both glue and the mylar film, so often the weak element of a laminate sail. Using a multi micro layered structure, elements of the membrane are fused together in a cross linked, polymerised matrix resulting in a stable, stretch resistant, and durable sail. By doing away with both glue and mylar film these sails are significantly lighter than conventional laminate sails. Not only is 4T FORTE™ intrinsically lighter than alternatives, but weight saving is enhanced by the fact that a 4T FORTE™ membrane does not need to be covered with extra woven taffeta fabric to protect it from UV or improve durability. Using components derived from recent developments for the military and biomedical science, MMS™ technology provides a robust and reliable sail skin, manufactured with the minimum of environmental impact and allowing realistic recycling options. Since glues, resins, and solvents have been replaced by heat activated fusion and the base polymer is 100% recyclable in a standard waste separation process, 4T FORTE™ sails can claim to be truly "green sails".

Multi Micro Structure (MMS™)  technology represents a leap forward in the production of sail material, leaving traditional mylar based laminates in its wake. A core structural grid, constructed from high modulus fibre takes care of the principal loads, whilst oriented micro layers provide strength in other secondary directions. The entire skin is encapsulated between ripstop "shields", which are UV, moisture, and mildew resistant. The whole skin, with its continuous fibres, is vacuum cured in a heat activated cross polymerisation process. which fuses the components together so that every single element in the structure contributes to shape holding. As a result, a 4T FORTE™ sail membrane not only exhibits superior structural integrity, but the use of more efficient components creates a sail up to 25% lighter than film based alternatives.

Thermo Moulded Sails

Unlike most of the membranes in the market that are built with the use of resins or glue, 4T FORTE™ membranes are made by a vacuum cured heat-activated cross polymerisation process. This ‘thermo moulding’ technology ensures superior structural integrity with no extra weight in the way of adhesives added to the sail. The cohesion of the different layers that create the flexible composite is obtained through the vacuum fusion of the thermoplastic elements which is why adhesives are not necessary. An added advantage of this process is that because no resins or glues are involved delamination is not possible and this term is therefore inappropriate with regards to 4T FORTE™.

STR Solid Stripes

For many years carbon has been the ultimate and dominant fibre in performance sailmaking. In 4T FORTE™ OneSails has instead introduced ‘STR Solid Stripes’ which have a better strength/weight ratio than carbon and a huge number of other advantages including being more robust, having higher tenacity and a full resistance to the harsh factors of the marine environment such as UV, temperature and moisture. These latest generation polymers have been developed relatively recently using a truly innovative synthesis processes. They are characterized by low specific weight and very simple chemical chains that are linked and rigid and which resist deformation by various aggressive spoiling agents.

STR Solid Stripes are similar to other products used in sailmaking such as Dyneema and Spectra, but they should be regarded as entirely distinct because they are not subject to the same kinds of issues such as shrinkage and creep. Moreover, they do not exist in the form of bundles of microfilaments, but as 'stripes' or thin homogeneous ribbons, presenting a significant contact surface and enhanced cohesion in the multi-layered microstructure within which it integrates perfectly.

As a consequence of the enhanced properties of these flexible composites, there will be a shift away from regarding racing sails as ‘disposable’ as 4T FORTE™  sails will be more durable with improved performance and better shape stability. In the cruising market the impact will be even bigger because it will be possible to have sails that last well, but which at the same time are lightweight, soft, dimensionally stable and with an attractive appearance.

Because 4T FORTE™ is a multilayer composite it can consequently be produced in many configurations with the modular style of construction lending itself to adaptation to meet the requirments of different end uses and budgets. At present the entry level version features structural yarns of Twaron with the next level featuring STR Solid Stripes. The premium version features a higher modulus version of STR Solid Stripes for larger boats and instances where performance cannot be compromised. The cruising variants of these three options feature a robust outer skin which offers enhanced UV, moisture & mildew resistance without the need for a heavy taffeta layer.