KATSONIS – S123

Type 214HN / Papanikolis-Class Air-Independent Propulsion Submarine

HS KATSONIS (S123) is one of the most advanced conventional submarines in the Hellenic Navy and the fourth unit of the Greek Type 214 / Papanikolis class.

Built at Hellenic Shipyards in Skaramangas, the submarine combines diesel-electric propulsion with fuel-cell Air-Independent Propulsion – AIP, allowing it to remain submerged for substantially longer periods than traditional diesel-electric submarines without using a snorkel.

The Hellenic Navy officially lists KATSONIS with a length of 65 metres, displacement of 1,858 tonnes and maximum speed of 22 knots, slightly higher than the 20-knot figure in the old short PiraeuShips description.

Vessel Details

Name: HS KATSONIS

Pennant Number: S123

Type: Diesel-Electric / AIP Attack Submarine

Class: Papanikolis class

Design: Type 214HN / Type 214/1700

Navy: Hellenic Navy

Builder: Hellenic Shipyards, Skaramangas, Greece

Greek Flag Raised: 14 April 2014

Formal Hellenic Navy Acceptance: 23 June 2016

Length: 65 m

Beam: 7.9 m

Height / Depth: 7.5 m

Displacement: 1,858 t

Accommodation: up to 40 persons

Maximum Speed: 22 knots

Propulsion: Diesel-electric with AIP

Main Electric Motor: PERMASYN

Diesel Generators: 2 × MTU-based generating sets

AIP: 2 × fuel-cell modules

Torpedo Tubes: 8

Weapons Capacity: 16 torpedoes / guided weapons

Countermeasure Launchers: 4

Current Status: Active.

Fourth Type 214HN

KATSONIS is the:

fourth Type 214 submarine

in Hellenic Navy service.

The class consists of:

PAPANIKOLIS – S120

PIPINOS – S121

MATROZOS – S122

and:

KATSONIS – S123.

PAPANIKOLIS was built in Germany, while the following three submarines were constructed at:

Skaramangas

under the:

ARCHIMEDES programme.

Built in Greece

KATSONIS therefore has particular significance for Greek naval shipbuilding.

The submarine was the:

third Type 214 constructed at Hellenic Shipyards.

The Greek flag was raised aboard the submarine on:

14 April 2014.

Its naming ceremony and formal acceptance took place on:

23 June 2016.

Air-Independent Propulsion

The defining feature of the Type 214 is:

AIP – Air-Independent Propulsion.

Traditional diesel-electric submarines must periodically approach the surface and operate their diesel engines using a snorkel in order to recharge batteries.

During that period they become:

easier to detect,

more vulnerable to radar,

and more exposed to anti-submarine aircraft.

KATSONIS can instead use:

fuel cells

to generate electricity while remaining fully submerged.

Fuel Cells

The official Hellenic Navy specification lists:

2 fuel-cell units.

Fuel-cell technology produces electrical energy through an electrochemical reaction rather than conventional combustion.

This gives the submarine:

very low acoustic signature,

reduced thermal signature,

and dramatically increased submerged endurance.

PERMASYN Motor

Propulsion is provided through a:

PERMASYN permanent-magnet electric motor.

This type of motor is particularly suitable for submarine operation because it combines:

high efficiency,

compact dimensions,

and very low acoustic output.

Quietness is one of the most important characteristics of any modern submarine.

22 Knots

The old PiraeuShips short text gives:

20 knots.

The Hellenic Navy's current official specification gives:

22 knots.

I would therefore update the article to:

Maximum speed: 22 knots.

Eight Torpedo Tubes

KATSONIS carries:

8 torpedo tubes.

The official Hellenic Navy page lists a total weapon load of:

16 torpedoes and guided weapons.

The submarine can therefore attack:

surface ships

and:

submarines

while remaining extremely difficult to detect.

Countermeasures

The ship also carries:

4 torpedo-countermeasure launchers.

These can deploy decoys intended to confuse incoming anti-submarine weapons.

Eastern Mediterranean Role

AIP submarines are particularly well suited to the:

Aegean and Eastern Mediterranean.

Complex underwater geography,

islands,

narrow passages,

and varying seabed conditions

provide ideal environments for a quiet submarine capable of remaining submerged for long periods.

The Type 214 fleet therefore constitutes one of the most strategically important components of Greek naval deterrence.

Named after Lambros Katsonis

The submarine is named after:

Lambros Katsonis – Λάμπρος Κατσώνης,

the eighteenth-century Greek naval commander who fought Ottoman forces in the Aegean before the Greek War of Independence.

The current vessel is the:

third submarine of the Hellenic Navy to bear the KATSONIS name.

The First KATSONIS

The first was:

Y-1 KATSONIS.

Built in France during the 1920s, the submarine served Greece during the Second World War.

It was sunk on:

14 September 1943

off Skiathos during combat.

The Second KATSONIS

The second was former U.S. Navy:

USS REMORA.

It entered Greek service in:

1973

as:

S115 KATSONIS

and remained operational until:

31 March 1993.

Active in 2026

KATSONIS remains part of the current Hellenic submarine force.

The Hellenic Navy's current fleet and Submarine Command pages continue to list:

KATSONIS – S123

among the four Type 214/1700 submarines.

PiraeuShips Record

KATSONIS (S123) was recorded by PiraeuShips as the newest member of the Hellenic Navy's Type 214HN / Papanikolis-class submarine force. Built at Hellenic Shipyards in Skaramangas under the ARCHIMEDES programme, the 65-metre submarine combines conventional diesel-electric generation with two fuel-cell Air-Independent Propulsion units and a highly efficient PERMASYN electric propulsion motor. This configuration allows KATSONIS to remain submerged for extended periods with an exceptionally low acoustic signature. The Hellenic Navy currently publishes a maximum speed of 22 knots, displacement of 1,858 tonnes and an armament capacity of 16 torpedoes and guided weapons launched through eight torpedo tubes. Still fully active in 2026, KATSONIS forms part of one of the most capable conventional submarine forces operating in the Eastern Mediterranean.

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