Nautical canvases are a type of canvas used in sailing and other nautical activities. They are typically made from strong, durable materials such as cotton or polyester, and are designed to withstand the harsh conditions of the sea. The term 'sails' is used to refer to the large pieces of canvas that are attached to the masts of a boat, allowing it to move through the water. These sails are an essential part of any nautical vessel, providing propulsion and stability.