I hate the mainsail furler – certainly that fixed to the mast, a little less that one housed in the boom – for different reasons. The first one, although less important, concerns aesthetic. That’s coming from a man who sails with the fenders placed on the deck and doesn’t care about elegance rules. But seeing a sort of shapeless pair of knickers instead of a beautiful mainsail rends my heart.
The first real reason concerns the reliability of the mechanism. And I’m willing to admit that my aversion is partially due to my age: I started to work as a journalist at the time of typewriters and to sail when the jib furler was regarded with suspicion. But even though modern mechanism ensure an almost total reliability, the risk that something can get stuck because of a sudden gust of wind is not excluded.
The second reason concerns the shape and surface of the sail: in a word, its performances. The mainsail has not only no battens (although the vertical ones can be added) but the final cut is such that it defines a carved leech which can, in its turn, wrap itself inside the mast. The result is a small unroached mainsail subject to the shadow created by a mast with an exaggerated diameter.
The third reason lies in the manoeuvre which must be precise. As already seen in the article published last May, it’s nothing overwhelming but it’s not unusual to hear about troubles faced by crews who are convinced that using a mainsail furler simply means to haul and cast two ropes. A correct tension of the leech, the basis and the leech line, a right position of the boom ( a rigid vang is almost compulsory) and correct tacks (port tacks if the head-rope is on the right and vice versa) are the necessary measures to adopt for a safe manoeuvre. This is far from easy to the point I can really doubt about the much vaunted greater convenience and advantages of the mainsail furler compared to a classic rig.
But there’s also an additional reason. A mast which has to house the mainsail furler mechanism and the mainsail furled is larger and heavier than a standard one, which translates into the need for a heavier keel to compensate the greater list.
According to Bertrand Cheret, the author of Les voiles. Comprendre, régler, optimiser, on a 15-metre boat, a classic mast is about 11 kg a yard while, with a mainsail furler, it can reach 15 kg a yard. ” If the mast was 18 m long – says Cheret – the weight would increase by 72 Kg and this mass would have a resultant placed at 9-10 m from the waterline. In order to compensate that, a ballast of 500 or 600 kg should be placed at little more than one metre under the waterline.”
Of course, a boat equipped with a mast specifically designed to support a mainsail furler will have an appropriate ballast. If, on the contrary, we modify the mast at a later stage, the problem related to excessive list, rolling and pitching must be taken into account.