To measure the forces acting on the sail, researchers have fitted it with a web of glass fibers. Credit: Fraunhofer HHI.

As mentioned in the previous post about Corning’s production of optical fibers, the fibers are most often associated with telecommunications applications. But, these glass fibers are robust optical tools, whose use is limited only by imagination, as evidenced by a new technology for optimizing sail tension and trim on sailboats using optical fibers and sensors integrated into the sail cloth. The system generates continuous reports via a smartphone app.

This new work comes from investigators at Fraunhofer’s Heinrich Hertz Institute. According to a news release from Fraunhofer HHI, the idea came from hearing demands from high-end racing yacht teams who are constantly looking for a new edge to up their speed (and, most likely, offering deep pockets). The idea of creating a nerve-like fiber optics-based technology, integrated with a fiber Bragg grating system, had already been proven as a way to monitor the loads placed on wind turbine blades and to detect failure points early enough to avoid catastrophic damage. With a FBG system, every bend, stretch or compression of a fiber alters the wavelength of light passing through it.

Fraunhofer HHI built on this “nerves of glass” concept by integrating a grid of optical fibers into a sail, and then designing a mini-spectrometer to rapidly sense and interpret the strains detected by the fibers.

Credit: Fraunhofer HHI.

Working with sailcloth manufacturer Dimension-PolyantIn, the Fraunhofer group formed a web of glass fiber containing 45 measuring points and attached them to the mainsail and a genoa. In tests under typical sailing conditions, the fiber system immediately discovered some unexpected strains, e.g., the strain at top of the sail was more than anticipated, while other regions of the sail experience lower than expected tension. Sailmakers can use this aggregated date to improve their design, for example, by reinforcing the areas that were subject to greater stress and using lighter material in the areas that were less stressed.

But data from the system can be also used to make immediate changes while onboard. Wolfgang Schade, who led the German team, says in the press release, “You also have to avoid pushing the equipment beyond breaking point. Fiber optic sensors can help to determine the forces acting on hulls, masts, and sails during the journey in real time.”

In a newer iteration of the system, Schade and his team also fit sail battens with fiber optic sensors. These sensors help the boat’s crew “find the optimal trim, i.e. the sail position at which the boat travels the fastest under specific wind and wave conditions,” explains Schade.

Fraunhofer reports that the detection equipment—an LED light source, spectrometer, WLAN network and other electronics—has been shrunk to the size of a cigarette pack, and Schade’s team has already developed an app that would allow crew members to access real-time data from their smartphones.

Fraunhofer is known looking for commercialization opportunities for its research and it is already marketing its new sail monitoring system, under the name nextSailSystem: Intelligent sails for regattas and cruising.