In the days of sail a merchantman's success as a trader was governed by the seamanship of her master and the sailing qualities of the ship. A vessel which could turn easily to windward in difficult conditions could sometimes manœuvre under sail, in and out of port, without assistance while her more ungainly sister was dependent upon warping, kedging and towage by craft under oars. More important still, when on passage the efficient sailing ship could get herself out of trouble if she found herself in a tight corner on a lee shore in a gale of wind.