Vertical Batten In-Mast Furling Mainsails

Adding vertical battens improves the performance of in-mast furling mainsails by allowing the sail to be built with roach (the area of a mainsail that protrudes beyond a straight line from the head to the clew). Having roach makes the sail bigger, and gives it a much more efficient aerodynamic profile. Even with vertical battens, the sail still has to be cut relatively flat so it will roll into the mast properly. To support even a modest amount of roach, the battens have to be twice as long as standard horizontal battens.

The pictures above illustrate how much bigger a vertical batten roller-furling mainsail is compared to a concave leech batten-less main. In the pictures, the Dacron batten-less main for a Beneteau 411 is laying over its partially finished replacement main, which is a vertical batten Tape-Drive sail.

The pictures above illustrate how much bigger a vertical batten roller-furling mainsail is compared to a concave leech batten-less main. In the pictures, the Dacron batten-less main for a Beneteau 411 is laying over its partially finished replacement main, which is a vertical batten Tape-Drive sail.

This sequence shows the finished Beneteau 411 sail with vertical battens and positive roach rolling into the mast.

This sequence shows the finished Beneteau 411 sail with vertical battens and positive roach rolling into the mast.