Greece to announce modernization of four Papanikolis-class submarines with new acquisitions under consideration.

As reported by OnAlert on March 13, 2025, the modernization of the four Papanikolis-class submarines and the procurement of new submarines are among the programs expected to be announced by the Greek Prime Minister in Parliament on March 27, 2025. Concurrently, the first batch of 44 SeaHake Mod4 heavy torpedoes is set to arrive at the Salamis Naval Base in early summer, following significant delays attributed to supply chain disruptions.
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The Hellenic Navy’s plan is to complete the Papanikolis-class modernization program alongside the delivery of new submarines, resulting in a fleet of nine operational submarines. (Picture source: Hellenic Navy)

The Hellenic Navy prioritizes enhancing its submarine fleet to maintain operational capabilities established with the acquisition of four Papanikolis-class submarines, based on the German Type 214, and the modernization of Okeanos (S-118), a Poseidon-class submarine based on the German Type 209. During the 2020 maritime crisis between Greece and Türkiye, these submarines reportedly tracked multiple Turkish surface vessels while remaining undetected.

The Papanikolis-class is based on the Type 214 submarine, a diesel-electric attack submarine featuring an air-independent propulsion (AIP) system utilizing Siemens polymer electrolyte membrane (PEM) hydrogen fuel cells. It has a length of 65 meters, a beam of 6.3 meters, and a submerged displacement of 1,860 tons. The submarine can operate at a maximum submerged speed of 20 knots and dive to depths approaching 400 meters. It is designed for an endurance of 84 days, with the ability to remain submerged for extended periods using its AIP system. The armament consists of eight 533 mm torpedo tubes capable of launching heavyweight torpedoes and UGM-84 Sub-Harpoon anti-ship missiles. Its propulsion system includes two MTU 16V-396 diesel engines, two Piller NTB56.40-10 charging generators, and a Siemens Permasyn electric motor, driving a low-noise skew-back propeller to minimize acoustic signature.

Two SeaHake Mod4 heavy torpedoes have already arrived at the Salamis Naval Base for training and certification purposes. These torpedoes lack explosive warheads and are instead equipped with devices that emit light and release a special liquid to facilitate retrieval after launch. They are guided by a fiber-optic cable from the submarine, ensuring precise tracking. Once their battery power is depleted, they surface for retrieval. The first training launches are scheduled for May, with additional exercises planned in the following months. The training torpedoes can be converted into operational weapons by installing 260 kg explosive warheads.

By the end of 2025, the Hellenic Navy is expected to receive most of the heavy torpedoes, which will replace the older SUT Mod0 torpedoes acquired in 1980 and the SST4 models that remain in use. The SeaHake Mod4 torpedoes are designed for speeds of up to 50 knots and a range exceeding 50 kilometers. They feature advanced electronic counter-countermeasures (ECCM) to resist interference and defensive countermeasures.

These torpedoes can operate with both active and passive targeting systems and are guided with precision via fiber-optic cables. They can be deployed from various depths under different sea conditions while evading modern decoys and countermeasures. Weighing over 1.5 tons, they carry 260 kg of explosive material, capable of causing significant damage to large naval vessels. The original delivery schedule for these torpedoes was set for 2023, but manufacturer Atlas Elektronik cited material supply issues related to the war in Ukraine as the cause of delays.

The Hellenic Navy’s fleet also operates five older Type 209-class submarines. Two "209/1100" units have been in service for over 52 years, while two "209/1200" units have nearly 45 years of operational history. The long-term strategy involves acquiring four new submarines to replace these aging vessels. The Hellenic Navy has expressed interest in several designs, including the German Type 209 1400 Mod, the French Scorpene Evolved and Barracuda, and the Swedish Saab A26. A key requirement is that these submarines be constructed in Greek shipyards to retain a portion of the investment within the national industry.

The Minister of National Defense, Nikos Dendias, has proposed an armament package that includes acquiring four new submarines alongside the Papanikolis-class modernization initiative. The Naval Staff has received political approval to conduct market research and request bids for the new submarines, which will be introduced gradually over the next decade. The upgraded Okeanos (S-118) submarine is projected to remain in service for at least 15 more years. The Hellenic Navy’s plan is to complete the Papanikolis-class modernization program alongside the delivery of new submarines, resulting in a fleet of nine operational submarines, including the Okeanos.