Parnaíba (U-17) is a river monitor

River monitor

River monitors were heavily armored, and normally mounted the largest guns of all riverine warships. The name originated from the US Navy's Brown Water Navy's USS Monitor, which made her first appearance in the American Civil War, and being distinguished by a single revolving turret.On 18 December...

 of the Brazilian Navy

Brazilian Navy

The Brazilian Navy is a branch of the Brazilian Armed Forces responsible for conducting naval operations. It is the largest navy in Latin America...

.

She was built by the Navy in Rio de Janeiro

Rio de Janeiro

Rio de Janeiro , commonly referred to simply as Rio, is the capital city of the State of Rio de Janeiro, the second largest city of Brazil, and the third largest metropolitan area and agglomeration in South America, boasting approximately 6.3 million people within the city proper, making it the 6th...

 and commissioned on 9 March 1938. She participated in the Second World War and is currently the oldest ship in commission in the Brazilian Navy, as well as the oldest naval vessel in the world still in active service (as opposed to museum ships in nominal commission). She is currently assigned to the Mato Grosso Flotilla.

Modernization

She underwent a modernization program at the Ladario Riverine Naval Base between January 1998 and 6 May 1999, which saw the replacement of her original reciprocating engine plant with diesel engines to increase her range and endurance. A helicopter platform has been fitted over the fantail, allowing her to operate the IH-6B Bell Jet Ranger III

Bell 206

The Bell 206 is a family of two-bladed, single- or twin-engine helicopters, manufactured by Bell Helicopter at its Mirabel, Quebec plant. Originally developed as the Bell YOH-4 for the United States Army's Light Observation Helicopter program, the 206 failed to be selected...

, replacing the UH-12 Squirrel Helibrás Monoturbina.