“A furling mainsail without battens (excuse the expression) is simply crap. The top 18 to 20% of the sail only create drag (resistance) and no lift/buoyancy (more heeling, more rudder pressure, less speed).
- A mainsail with short vertical battens is already better, but the leech rounding is still limited, which mitigates the points described above but does not really cancel them out. Furthermore the short battens have no reefing function (see below). The main reason against short battens, however, is that they can get jammed in the mast on the starboard inner mast edge (when, as usual, furled anti-clockwise). This does not happen often, but when it does you have a real problem.
- The only argument against full battening is the higher price. These sails produce more propulsion, less heeling, less rudder pressure. Furthermore, the battens are perfect reefing steps. The battens are not parallel to the luff, but slightly slanted. Reefing should now always be done in such a way that the batten is always completely furled into the mast. It then winds itself slightly around the pole in the mast as a spiral and thus stretches the "new luff" a little.
After more than 25 years of producing fully battened furling mainsails we have never had one owner who was not satisfied with the conversion.”
I have to add: The battens are round (diameter some 8 to 10 mm) and made of two different materials: glass fibre and carbon, the latter used in the upper part of the sail to keep the aft part stiff.
Further I have to add this: When we got our Mago del Sur in March 2016 she was fitted with original genoa, main and mizzen. (The jib had disappeared.) Main and mizzen were bare of the vertical battens. The leeches of all three sails were worn out and causing enormous flapping and vibrations. In spite of that the performance of these sails was surprisingly good. When we had to furl in the main the first time during our delivery trip (with winds of some 7 Beaufort) the furling system blocked because of overload. Thus giving us the chance to furl in the main by hand. Which worked very well.
In July 2016 we ordered new genoa, jib, full battened main and full battened mizzen from Jens Nickel. Since then we never had any problem to furl in or out main and mizzen. We can do it on all angles to the apparent wind and in all wind speeds we have met until now. The furling systems never blocked. Meanwhile we sail the full batten sails some six years without any problems.
But there is one aspect you have to know if you think about a full batten sail. The connection between halyard and sail has to be reliable. Once it happened that a boatyard fitted our main to the mast with an unreliable connection. I insisted to change it but I forget to proof the connection after the main mast was fitted on the boat. After 3 hours of sailing the main came down - more or less half way and creating an interesting S-shaped new sail design because the battens blocked the rest of its way down. It was quite a nice job to get the battens out of their pockets piece by piece …