At a Glance
- Researchers used mathematical models to understand why sails successfully flip during a tacking maneuver or get stuck in a less effective shape when sailing against the wind.
- A successful flip is most likely to occur with sails that have high stiffness, significant pre-turn tension, and a larger final angle relative to the wind’s direction.
- The speed of the flip is mainly influenced by the sail’s mass and the specific speed and acceleration profile used by the sailor to execute the turning maneuver.
- The study also determined that slack sails, which lack sufficient initial tension, present a greater challenge and are significantly more difficult to flip during a tacking motion.
- These findings provide a valuable framework for designing more effective sails and enhancing the reliability of autonomous research vessels that must navigate unpredictable wind conditions without human intervention.
Tacking, a zig-zag maneuver used to sail against the wind, is one of the most fundamental yet complex skills in sailing. While essential for everything from weekend journeys to competitive racing, the complex interplay between the wind and the sail during this high-stakes turn is not fully understood. During a tack, the sail must cleanly flip from one side to the other; however, it can sometimes get stuck, costing precious time and momentum.
In a new study published in the journal Physical Review Fluids, mathematicians from New York University and the University of Michigan offer a detailed look into what makes a tack successful. The researchers, led by Christiana Mavroyiakoumou of NYU’s Courant Institute of Mathematical Sciences and co-authored by Silas Alben, a professor at the University of Michigan, used a combination of mathematical modeling and computer simulations. This approach allowed them to precisely study how a sail membrane interacts with the wind and how the wind changes in response during the maneuver.
The team’s computations revealed that three main factors determine whether a sail successfully flips. A successful tack is most likely with a sail that has high stiffness, meaning it is less flexible and does not curve excessively. Strong tension in the sail before it catches the wind also helps, as does a final angle of about 20 degrees between the sail and the wind. Other factors, like the sail’s mass and the speed of the turn, primarily affect how fast the flip happens rather than if it happens at all. The researchers also found that slack sails are much more challenging to flip correctly.
“By uncovering what determines a successful flip and how long it takes, this research gives sailors and engineers a new resource for mastering the wind,” Mavroyiakoumou said in an NYU press release. Beyond the race course, these findings could have a significant impact on the design of autonomous sailboats, which are vital for oceanographic research. Making these robotic vessels more efficient and reliable when changing direction in unpredictable conditions is a key step in advancing their scientific capabilities.
References
- Devitt, J. & New York University. (2025, July 17). New study tackles dynamics of common—And difficult—Sailing maneuver. Phys.Org; New York University. https://phys.org/news/2025-07-tackles-dynamics-common-difficult-maneuver.html
- Mavroyiakoumou, C., & Alben, S. (2025). Sail dynamics during tacking maneuvers. Physical Review Fluids, 10(7), 073901. https://doi.org/10.1103/37xg-vcff
