All sorts of boat handling manoeuvres under sail are more easily executed under mainsail only. Often, this involves sailing closehauled, which is where problems can arise. A close-hauled headsail ‘bends’ the wind around the back of the mainsail, which means the main must be sheeted in very hard to stop it back-winding – often almost to the yacht’s centre-line. This is fine so long as it’s working in conjunction with the genoa. If it is sheeted in tightly without a sail forward of it, the magic stops working and the power is virtually all sideways. Maximum leeway, minimum drive. Without the curved air coming off the jib, the main can be eased well off, even when the boat is only 45 degrees from the true wind. She’ll point just as high, go twice as fast and, more importantly, will steer like a dream.