/ Whether for foils, masts, longitudinal stiffeners or catamaran structures, composite parts used in the yachting industry are now reaching levels of mechanical stress that are forcing shipyards to review their processes. Behind the rigidity gains sought, another subject is becoming central to workshops: mastering vacuum infusion on ever-thicker laminates. With Steady Plus UD, SAERTEX targets this very issue with a unidirectional NCF reinforcement developed to secure the impregnation of complex laminates.
Heavy thicknesses complicate vacuum infusion
In modern composite structures, thick laminates remain difficult to impregnate evenly. As thickness increases, so does the risk of dry spots.
On highly stressed parts such as foils or structural reinforcements for multihulls, a faulty impregnation can locally modify the mechanical characteristics of the composite. Compressive strength, tensile strength and overall rigidity become less predictable.
In vacuum infusion, resin flow control remains a critical parameter. The flow must remain regular along the entire length of the laminate to avoid air traps and internal defects.
SAERTEX explains that it has developed the Steady Plus UD textile architecture to improve resin circulation in closed processes such as vacuum infusion or RTM. The manufacturer claims homogeneous impregnation on thicknesses of up to 70 mm.
Unidirectional reinforcements meet new mechanical loads
The development of foils and load-bearing appendages is profoundly modifying the constraints applied to composite materials in the nautical sector. Unlike conventional hull structures, these parts often work with highly concentrated loads and high dynamic forces. This has prompted architects and design offices to favor reinforcements that are precisely oriented in the load axes.
Unidirectional fabrics enable fibers to be aligned in the main direction of stress. This approach improves the mechanical performance of the composite while limiting unnecessary weight.
Steady Plus UD belongs to this family of NCF reinforcements, which stand for Non Crimp Fabric, i.e. fabrics without fiber crimp. This type of construction avoids some of the mechanical losses seen in traditional woven fabrics, where crossed fibers slightly alter their trajectory.
SAERTEX claims gains of up to 15% in tensile and compressive properties compared with standard UD fabrics or certain woven fabrics.
Textile stability becomes a production issue
In composites workshops, mechanical performance is no longer enough. Teams are also looking for materials that are easy to handle and repeatable in production.
Some unidirectional reinforcements have fiber deformations or fraying problems during cutting and ply placement. These defects complicate draping quality and increase variations between two identical parts.
SAERTEX says it has worked on the fabric's stability to limit fiber displacement during handling. The manufacturer also points to a good draping capacity, particularly useful for complex geometries or parts with significant curvature variations.
In the marine sector, this problem directly concerns hull joints, link arm junctions on catamarans, or certain foil areas where changes in cross-section require delicate shaping.
Reducing resin consumption remains an economic challenge
Controlling the fiber-resin ratio remains an important issue in composite construction. Too much resin makes the part heavier without providing any significant structural gain.
The manufacturer claims a fiber content close to 60%, with a possible reduction in resin consumption of up to 27%. For building sites, this aspect has as much to do with final weight as with production costs.
In marine applications, this search for optimization particularly concerns movable appendages and high structures, where every kilogram has a direct influence on the boat's dynamic performance.
And in both large-scale production runs and small, specialized production runs, process stability is becoming as important a criterion as material performance alone.
The marine applications in question mainly concern heavily loaded structures
SAERTEX points out that Steady Plus UD is already used on several marine composite parts requiring reliable infusion and high mechanical properties.
In particular, the manufacturer cites localized reinforcements on catamarans, as well as heavily loaded components such as foils. These applications generally combine several difficulties: high thicknesses, high dynamic loads and high surface quality requirements.
The material is still available in various configurations, with glass or carbon fiber depending on the constraints required.
In the nautical sector, this versatility means that stratification architectures can be adapted to suit different boat programs, from production structures to more technical appendages from the world of racing or foiling dayboats.
