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Tridente-class profile
NRP Tridente at the Lisbon Naval Base
Class overview
Builders	HDW
Operators	Portuguese Navy
Preceded by	Albacora class
Planned	3
Completed	2
Cancelled	1
General characteristics
Type	Attack submarine
Displacement	1,700 tons (surfaced) 2,020 tons (submerged)
Length	67.7 m (222 ft 1 in)
Beam	6.35 m (20 ft 10 in)
Draught	6.6 m (21 ft 8 in)
Propulsion	Diesel-electric, fuel cell AIP, low noise skew back propeller
Speed	20 knots (37 km/h; 23 mph) submerged 10 knots (19 km/h; 12 mph) surfaced 6 knots (11 km/h; 6.9 mph) AIP system
Range	12,000 nmi (22,000 km; 14,000 mi) at 8 knots (15 km/h; 9.2 mph)
Endurance	45 days
Test depth	superior to 300 m (984 ft)
Capacity	14
Complement	7 officers 10 petty officers 16 enlisted
Sensors and processing systems	Kelvin Hughes KH-1007 (F) navigation radar Atlas Elektronik GmbH ISUS 90 combat management system
Armament	(8) 533 mm (21.0 in) torpedo tubes, (4) subHarpoon-capable 12 × WASS Blackshark torpedo reloads

The Tridente-class submarines, also designated as U 209PN, are diesel-electric submarines based on the Type 214 submarine developed by Howaldtswerke-Deutsche Werft GmbH (HDW) for the Portuguese Navy.

This class of submarines was acquired by Portugal to replace the previous submarines of the Albacora class, then being operated by the navy. Originally, HDW proposed the Type 209 submarine (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 marine animals, thus breaking a tradition retracing back to 1913, when the first submarine entered service with the Portuguese Navy.

The Tridente-class submarines are wrongly classed in the "diesel-electric" class. Their propulsion is exclusively electric, with electric motors powered by batteries. These batteries may be charged while submerged by "fuel-cells" (inverse electrolysis) for which, this submarine carries a huge supply of liquid oxygen and hydrogen. Also, and solely as a second solution for recharging the batteries, this submarine carries two powerful diesel-electric generators (1,000 KVA) for use only when surfaced, or at snorkel depth.

Submerged, from Lisbon, Portugal, submarines of the class may reach the Cape of Good Hope and return, in 15 days.

• 
  Portuguese Navy submarine NRP Tridente at Naval Station Norfolk
• 
  NRP Arpão at Lisbon Naval Base
• 
  NRP Tridente under construction
• 
  NRP Tridente at Howaldtswerke-Deutsche Werft at Kiel shipyard

Wikimedia Commons has media related to Tridente class submarines.

• Tridente class Archived 2016-03-03 at the Wayback Machine information at the Portuguese Navy website (in Portuguese)
• 209PN profile Archived 2010-11-11 at the Wayback Machine at the Portuguese Navy website (in Portuguese)
• Submarino de ataque (SSK) classe Tridente (tipo U-214) - Área Militar Archived 2009-05-25 at the Portuguese Web Archive (in Portuguese)
• Acquisition history of the U-209PN class Archived 2021-08-28 at the Wayback Machine (in Portuguese)
• Article about the differences between the U209, U212, U214 and U209PN Archived 2021-02-11 at the Wayback Machine (in Portuguese)