In-Boom Furling Mainsails

A furling boom is the way to get the ease of a roller mainsail without having to buy a new mast. Several companies make booms that allow a full-batten main to be rolled into the boom. These mains have all the benefits of a standard full-length batten main, yet they can be roller reefed or furled into a specially made boom. Furling booms offer a huge safety benefit over any in-mast furling sail, in that if the furling system jams or fails, you can always drop the sail to the deck and get it down. If an in-mast furler jams, you are stuck with some portion of the sail flapping in the wind. Furling booms work well for large boats where the boom is too high to furl and cover the main. Furling booms can be a retro-fit to an older boat or it can be specified on a new boat.

Above is a comparison of two Najad 440s. The one in the foreground has a furling boom and the one in the background has an in-mast furling main.

A close-up of a boom-furling mainsail. 

Boom furling mains are reefed to a full-length batten. Once the batten is rolled tight against the mandrel inside the boom, the sail’s reefed foot is pulled straight, which makes the foot flat for a well-reefed shape.