Traditionally, rudder stocks of ships and very large yachts are built using stainless steel / SAF metal alloy. Because of increasingly higher performance demands, rudder blades designs tend to be thinner. This, of course, poses a challenge in terms of strength as high forces can build up when the rudder is subjected to high loads when sailing. To cope with these enormous forces while maintaining a high performance design. A better – stronger material was chosen; carbon UD fibre composite laminates. To optimally utilize this potential, the carbon fibers are laid along the length of the rudder stock, where most forces are at play. Besides beneficial properties of carbon composite such as lightweight, strength and rigidity, composite also allows for increasing layer thickness in places where it’s most needed resulting in a lean, not overly heavy built rudder – built just right. A sacrificial tip can be designed functioning as an ‘intended weakest link’. In case of a grounding, the tip will break instead of losing the rudder or severely damaging the rudder quadrant. Even after losing the tip, the ship will remain operable and can still be maneuvered, with the remaining rudder still sealed from any leakage.
For a current 81 meter project, the world’s largest aluminum sailing yacht (to be delivered in 2020), Rondal has produced to biggest rudder to date within the superyacht industry. Even though the rudder was thoroughly engineered with FEM (finite elements method) simulations to calculate its strengths, the team was still curious about real world forces in various sailing conditions.
In close collaboration with partners Gurit, Com&Sens and Royal Huisman, Rondal developed a rudder with load sensing capabilities.
This was achieved by integrating optic fibers into the rudder’s composite layers. A similar method has also been applied in other industries such as wind generators and bridges to measure bend and movement. Feeding back this real world data into engineering and comparing the actual data with the FEM model, this effort and new approach will yield further learnings and insights contributing significantly to Rondal’s specialism and R&D while deepening our expertise.
Looking into the future, this technology has even more potential and opens doors to a new world of possibilities. Imagine a sailing yacht fully equipped with such load sensors; on its rudders, keel, mast, boom, stays, winches and blocks for example. This would enable real time monitoring & control of all dynamic forces at play; pushing performance while preventing damage and increasing crew safety on board. Also preventive maintenance can be done based on the logged data.