The Tridente class, also designated as U 209PN, is a diesel-electric

Diesel-electric

Diesel-electric transmission or diesel-electric powertrain is used by a number of vehicle and ship types for providing locomotion.A diesel-electric transmission system includes a diesel engine connected to an electrical generator, creating electricity that powers electric traction motors...

 submarine

Submarine

A submarine is a watercraft capable of independent operation below the surface of the water. It differs from a submersible, which has more limited underwater capability...

 class based on the Type 214 submarine

Type 214 submarine

The Type 214 is a diesel-electric submarine developed by Howaldtswerke-Deutsche Werft GmbH . It features diesel propulsion with an air-independent propulsion system using Siemens polymer electrolyte membrane hydrogen fuel cells...

 developed by Howaldtswerke-Deutsche Werft GmbH (HDW) for the Portuguese Navy

Portuguese Navy

The Portuguese Navy is the naval branch of the Portuguese Armed Forces which, in cooperation and integrated with the other branches of the Portuguese military, is charged with the military defence of Portugal....

.

This class of submarines was acquired by Portugal

Portugal

Portugal , officially the Portuguese Republic is a country situated in southwestern Europe on the Iberian Peninsula. Portugal is the westernmost country of Europe, and is bordered by the Atlantic Ocean to the West and South and by Spain to the North and East. The Atlantic archipelagos of the...

 to replace the last submarines of the Albacora class

Albacora class submarine

The Albacora class is diesel-electric attack submarine developed for the Portuguese Navy based on the French Daphné class submarine....

, then being operated by the navy. Originally, HDW proposed the Type 209 submarine

Type 209 submarine

The Type 209 is a class of diesel-electric attack submarine developed exclusively for export in the late 1960s by Howaldtswerke-Deutsche Werft of Germany...

 (U-209) during the competition, but decided to later enter a new proposal based on the Type 214. It is for this reason that the Tridente class is commonly designated as the U 209PN.

The class and its ships are the first to not be named after fish, thus breaking a tradition retracing back to 1913, when the first submarine entered service with the Portuguese Navy.

Ships

Pennant Pennant number In the modern Royal Navy, and other navies of Europe and the Commonwealth, ships are identified by pennant numbers...	Name	Laid down	Commissioned
S167	NRP Tridente	2005	May 2010
S168	NRP Arpão	2005	December 2010

External links

• Tridente class information at the Portuguese Navy website (in Portuguese)
• 209PN profile at the Portuguese Navy website (in Portuguese)
• Submarino de ataque (SSK) classe Tridente (tipo U-214) - Área Militar (in Portuguese)
• Acquisition history of the U-209PN class (in Portuguese)
• Article about the differences between the U209, U212, U214 and U209PN (in Portuguese)