A sailing ship traditionally has at least one mast to hold up sails. These sails use the wind to move the ship. The rigging helps support the sails on the mast, all of which are attached to the superstructure of the ship; the hull. Sailing across oceans can be dangerous due to a lack of wind, which leads to being becalmed, or too much wind which may direct the ship in an undesirable direction. With the emergence of steamships in the early 19th century, vessels containing a steam engine allowed greater manoeuvrability from ships. Inevitably, steamships replaced all sailing ships. By 2006, automated sails were developed, as such advancement in hybrid ships progressed it lead the way for reinvigorating the age of sail.