The sailing freighters which ply between the islands are called batheli. They come from the outlying atolls to the capital, Male, which is the only trading and trans-shipment centre. A canopy made of palm-leaves protects the crew and their cargo from rain and spray. Longer voyages can take weeks, even months, when wind conditions are unsettled. Not until the 1970s were the first sailing-ships fitted with diesel engines.