En flûte (French: "as a fluyt") is a French naval expression of the Age of Sail to designate the use of a warship as a transport with reduced armament. Some warships, ships of the line or frigates, were occasionally used with limited artillery, by reducing the number and calibre of their guns. Since ships have a limited amount of cargo space, they may be armed en flûte to make room for other cargo, such as troops and ammunition. That reduces the ship's ability to defend herself if attacked.