4T FORTE™ is OneSails’ patented continuous yarn sail membrane — a film-free sail construction built on exclusive Multi Micro Structure (MMS™) technology. At its core are STR Solid Stripes™, a proprietary high modulus, low-stretch structural fibre that replaces both adhesive and mylar film — traditionally the weakest element in any laminate sail. Elements of the membrane are fused in a cross-linked, polymerised matrix, creating a delamination-free sail that is stable, stretch-resistant, and up to 25% lighter than film-based alternatives.
That weight advantage goes further than the construction alone. Unlike conventional laminates, a 4T FORTE™ membrane requires no additional woven taffeta to protect against UV or improve durability. The entire skin is encapsulated between integrated ripstop shields — UV resistant, moisture-proof, and mildew-resistant — that are structural elements in their own right. A core grid of high modulus fibre manages principal loads. Oriented micro layers handle the rest. Vacuum cured through a heat-activated cross-polymerisation process, every element contributes to shape holding. Nothing is passive.
The result is a lightweight performance sail and a shape-holding sail in one — with superior structural integrity across the full working life of the membrane. First introduced in 2007 and continuously developed through fifteen years of grand prix sail and offshore racing, 4T FORTE™ is today the most advanced durable racing sail membrane available to competitive sailors. And the only one that is a fully recyclable, ISO certified sail.
Learn more about the revolutionary technology of making 4T FORTE™ membranes.
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.
OneSails 4T FORTE™ sails are simply the best sails available in the market in terms of quality, technology, shape holding and durability. These sails carry as standard a number of exclusive features that significantly increase their performance, lightness and ease of use:
4T FORTE™
625R
REFERENCE: top mylar membranes
Structural yarns
STR Solid Stripes™ High Modulus
Carbon
Color
Black
Clear film
Main structure modulus
245
210
UV stability proportion
1,9
1
4T FORTE™
325N
REFERENCE: top mylar membranes
Structural yarns
STR Solid Stripes™ High Modulus
Carbon
Color
Black
Clear film
Main structure modulus
245
210
UV stability proportion
1,7
1
4T FORTE™
620C
REFERENCE: top mylar membranes
Structural yarns
STR Solid Stripes™ High Modulus
Carbon
Color
Pearl or Titan grey
Different colors
Main structure modulus
245
210
UV stability proportion
1,5
1
After many years of carbon being the ultimate fibre in sailmaking, OneSails has introduced STR Solid Stripes™ with 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.
Where carbon degrades under repeated flexing and absorbs moisture over time, STR Solid Stripes™ holds its structural properties from the first race to the last. It does not refine carbon as the backbone of a performance membrane. It replaces it.
STR Solid Stripes™ High Modulus
CARBON High Modulus
CARBON
DYNEEMA
TWARON High Modulus
BLACK TECHNORA
Specific modulus (N/tex)
185
162
134
110
105
53
Load / weight ratio
1
0,88
0,72
0,59
0,39
0,29
UV stability
Tenacity
Flex Loss
Creep free
Moisture resistance
Carbon Footprint
The OneSails group has a shared passion for sailing and the sea. Respect for the environment keeps us focused on how we can continually improve the sustainability of our sails.
Our commitment to reducing the carbon footprint of our sails is centred on the materials and what happens to a sail at the end of its life. In 2015, OneSails launched 4T FORTE ™ sails and membranes recycling process. Awarded ISO 14040 Life Cycle Assessment Certification, 4T FORTE ™ are the only fully recyclable membranes on the market today.
Membranes and their assembly have been engineered for highest standards in terms of environmental impact and recyclable options. Glues, resins and solvents have been replaced by heat fusion and the base polymer is 100% recyclable in a standard waste separation process.
Holds to the highest standards of environmental practices and the responsible sourcing of materials and energy sources.
Sails made of 4T FORTE are produced with a low level of CO2 emissions into the atmosphere and without the use of pollutants such as glues, resins and solvents.
At the end of their useful life, these sails are recycled within the normal recovery processes of polyethylene-based raw materials to generate the PE pellet.
The polyethylene pellet is used for the production of accessories (such as headboards) to be used in the production of new sails.
For the first time ever!
Over 10 years of research and development have led to the creation of sails that win in regattas, last over time, have low CO2 emissions during production and can be recycled at the end of their life.
Matt Sheahan spent two days inside the production facilities in Italy looking closely and learning how sails are made and how OneSails is at the forefront of sustainable sailmaking.
For the first time ever!
Over 10 years of research and development have led to the creation of sails that win in regattas, last over time, have low CO2 emissions during production and can be recycled at the end of their life.
From this idea were born the MARKERS deriving from the sails used in the Vendée Globe by Pip Hare made by @carioca_italia
We strongly believe in sustainability. Our commitment is concrete and certified according to: ISO 14021:2021 and ISO 14001:2015 by independent auditors (IQNet).
Flexon Composites fabricates the 4T FORTE™ membrane, designed to be recovered at the end of its life. The membrane is shipped to sailmakers for finishing.
The process of making a sail includes:
At the end of use, accessories are removed to allow recycling. Membrane collection and disassembly are handled by the OneSails network in cooperation with Flexon and PoliEco, which offer the possibility of properly preparing membranes for recycling into reusable PE granules.
To prepare the membrane for recycling, the Loft, following instructions for the effective separation of components provided by Flexon, must:
Recycling will produce PE granules that can be reused in the plastics industry. Recovery depends on the presence of collection networks and recycling plants. Without them, Flexon and OneSails can handle the collection and sending to European plants.
OneSails can deliver 4T FORTE™ main sails with integrated thin cell PV panels, which regenerate the yacht’s batteries using solar energy.
Due to the high modulus construction of the 4T FORTE™ composite material, the impact of the PV panels is minimal in terms of the sail’s characteristics and performance.
For example, the Spirit 44CR(e) is a fully electric yacht designed and built by Spirit Yachts. To fit with the owner’s brief of ‘near total self-sufficiency’, OneSails worked closely with Spirit Yachts and Solar Cloth to integrate solar panels into the 4T FORTE recyclable mainsail. The three panels on each side of the sail have the capacity to regenerate 560watts, or 1,120watts total for both sides of the sail. Solar panel technology is always improving and OneSails is continually testing and developing new solutions.
For over 15 years the OneSails design team have developed exclusive technologies to make one-piece continuous thread sails a reality for cruising and racing boats.
Features like weight, shape control and deformation resistance means better performance compared to traditional panelled sails.
Sails are designed and manufactured to the very highest standards from carefully selected components to ensure the very highest quality and durability. 4T FORTE™ membranes are exclusively made in Italy. All the assembly process is completely made in a unique factory ensuring the meeting of all the required standards.
The best sail shapes are the result of continuous analysis and experience. OneSails is at the forefront of the sailmaking industry, continually investing in research and development to ensure that the very best sail shapes are available. The success of this approach is confirmed by the vast array of racing trophies OneSails clients have won, competing at National, International and World Championship level.
A core activity for every OneSails Loft is providing first class service, support and assistance. As part of our service commitment, each OneSails Loft has a team of experts on hand to ensure that we can deliver on our service pledge. In addition to a growing number of principle lofts, the OneSails Group has an extensive network of service centres strategically placed worldwide’s coast line.
YOU WILL SOON RECEIVE AN E-MAIL WITH THE LINK TO DOWNLOAD THE 4T FORTE BROCHURE.
YOU WILL RECEIVE AN E-MAIL SOON WITH THE LINK TO DOWNLOAD THE SUSTAINABLE BROCHURE.
YOU WILL SOON RECEIVE AN E-MAIL WITH THE LINK TO DOWNLOAD THE CERTIFICATE OF SUSTAINABILITY.
