The shape of the sail depends on the flex of the battens .
The battens do the opposite of what would be most desirable : they bend only a little when the wind is light , and they bend a lot when the wind is strong .
The shape of the sail depends on the flex of the battens , and the battens do the opposite of what would be most desirable : they bend only a little when the wind is light , and they bend a lot when the wind is strong .