Medieval seamanship under sail
By Tullio Vidoni
Master’s thesis, University of British Columbia, 1987
Abstract: Voyages of discovery could not be entertained until the advent of three-masted ships. Single-sailed ships were effective for voyages of short duration, undertaken with favourable winds. Ships with two masts could make long coastal voyages in the summer. Both these types had more or less severe limitations to sailing to windward. To sail any ship successfully in this mode it is necessary to be able to balance the sail plan accurately. This method of keeping course could not reach its full development until more than two sails were available for manipulation. Rudders never were adequate to hold ships to windward courses. Ships with three or more masts could be sailed in all weather with very little dependence on the power of the rudder and the freedom from this limitation made it possible to build ships large enough to carry sizable crews, their stores and spare gear over ocean crossings.