Battens

High Performance Sail Battens

2010 - 2012

A batten with improved stability and stiffness. For now used as full batten.

Project started spring 2010. Leaded by Eric J., in collaboration with Borja F. Michel P. made the first prototypes. Damien P. did the first study of materials, Ritxi builds the battens

Prototypes of sail battens for J80. 2012 03 21.

Innovation. The front part of the batten (in the camber of the sail) has a variable stiffness. The batten becomes rigid only when the sail is trimmed and the camber of the sail is optimal.

In this configuration the batten resists to deformations even in strong wind and/or wind gusts (indeed, within some limits).

This differs from a conventional batten, which only sets the sail under tension (stretch) and whose stiffness increases as the camber (and the curvature of the batten) increases.

At rest, the batten is flexible and the sail is soft, which facilitates tacks and gybes. See video 'batten checkup...' below.

This batten only needs minimal precompression (unlike classical battens) thus the stretch of the fabric and the pressure on the rigging is reduced.

Left: batten at rest. Right: camber of the sail reached.

Strength and stiffness.The materials and the profile of the batten are determined to provide high stiffness as well as high rupture loads.

The batten is made of a carbon-polycarbonate sandwich bonded with a high performance epoxy adhesive. This construction is lighter than plain carbon bars and provides similar stiffness.

The section of the batten (width and thickness) optimizes the trade-off between resistance and stiffness. For security, the structural calculus are systematically verified in laboratory.

In addition, there is a system to prevent the twist of the batten in the sleeve, which may cause permanent damage (many classical battens remain twisted after a season).

Finally, there is a also a damage-control system (lacing of high resistance elastic rope). In case of rupture the batten becomes flexible but remains functional. In addition the lacing holds the broken pieces of carbon in position (otherwise they would cut the sail like knives).

Construction and calibration. Made of high quality industrial materials, assembled and calibrated individually.

The materials are pultruded UD carbon epoxy (more than 70% carbon), mechanized polycarbonate, high resistance epoxy adhesive (designed for nautical applications), and an elastic rope Technora-latex produced especially for this project.

The batten is calibrated to meet the camber and the profile of the sail (exclusive method, patent WO 2012 -045893). There are standard configurations. However customization is remarkably easy.

State of the project (spring 2012): tests at sea

Tests - offshore sailing - completed (for now)

7 days single-handed sailing, crossing the Gulf of Viscay back and forth + coastal navigation in the Basque Country, wind between Force 0 and Force 8.

Boat: RM 1050, 35 feet bi-keel, mail sail 35m2 radial hydranet, 4 full battens from 1.10m to 4.10m.

Observations

The mainsail keeps its profile at all wind angles, from Force 1 to Force 8.

The sail remains flat in wind gusts, therefore the boat does not heel too much. For instance, open beating in wind gusts up to 36 knots, full sail up, the boat is steered with two fingers.

See videos below.

VIDEOS

open beating, force 6, 7

open beating, wind gusts force 8

checkup of batten after 7 days.

More tests - south transatlantic cruise

The same prototypes were used for a south transatlantic cruise. They held more than 4000 miles, including more than 1000 miles in strong conditions (force 7 and above). Good score for prototypes.

Tests - competition - pending

Sets of battens built for several competition boats (from J80 to a 44" ). Not tested yet (2012 06).

2014 - Bad!

New implementation, based on lashing with high modulus rope. Low cost, but low precision and a lot of work (drilling, lashing).

Clumsy project with a startup specialized in sail numerical simulation and a competitor. I made prototypes trying to reproduce 1) a numerical profile of sail and 2) the stiffness of competition battens (data from a sail maker)

Double mistake: 1) the stiffness of our battens is precisely much higher than that of conventional ones, 2) given that these prototype battens where flexible, the camber kept increasing beyond thee stability position.

2015 - 2016 - New design.

After this failure, I went back to fundamentals. There is now an efficient design.

Last year, I wrote: "If nothing fails, these battens will be on our boat(s) for the next navigation (October 2015)".

Done. Prototypes built in a hurry, mounted on Sonabia for the trip Mares del Sur, tuned between Hendaye, France and Piriapolis, Uruguay, currently sailing in Tierra del Fuego.

More information coming soon.

Updated 2016 05 07.

.