For decades, boats with in-mast furling mains have been sailing around with under-performing sails. These hollow-roach sails are starved for power and the boat ends up with leeward helm since the mainsail is too small to balance the genoa. BUT, they are popular because in-mast roller-furling mains are convenient – no one has to leave the cockpit to reef or furl the main and there is no sail cover to put on.
      Now sailors have three good options for getting the convenience of a roller furling sail with the performance of a well-shaped sail with roach. The three options are: Vertical battens, AirBattens and roller-furling booms.
        Upgrading from a batten-less sail will make your boat more sprightly and fun to sail because a main with roach is not only bigger, but it has a better aerodynamic profile. The photo on the left shows a Hinckley Bermuda 40 with a furling mast, yet the vertical betters allow the sail to have a reasonable amount of roach. The photo on the below shows how much sail area is lost when a furling main has negative roach because it has no battens.

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