A sailing boat which requires the tiller to be held up towards the weather side of the boat is said to ‘carry weather helm’. The weather helm is required to resist the yacht’s natural tendency to luff, or turn into the wind. This tendency is common to most single-hulled sailing craft and results from the fact that when the boat is heeled, the thrust of the sails acts well to leeward of the drag of the hull, resulting in a rotating couple. Some boats carry Lee helm in light winds, when they are sailing almost upright – that’s to say the helm has to be held Down towards the leeward side to prevent the boat’s turning away from the wind. Although quite acceptable in light winds, lee helm is undesirable if it persists in fresher breezes. Weather helm then has the benefit that the boat’s natural tendency in a gust is to turn head to wind, and so relieve the heeling (and possibly capsizing) pressure of the wind on her sails. (See also: Balance)