Dhow is actually a generic name of a number of traditional Arab sailing vessels with one or more so-called lateen sails. Lateen sails are triangular sail set on a long yard mounted at an angle on the mast. Although dhows are still made without blueprints, power tools - or even nails - they are still very common along the East African coasts of Mozambique, Tanzania, Zanzibar and Kenya.
btw - back in the days the traditional European ships were depending on having the wind behind them. The dhows, which are still build in the same way they were already build centuries ago, are having adjustable sails that can be turned to catch the wind from any direction.