July 10, 2012:
Iran makes frequent announcements about the growth and modernization of its submarine force. The latest press release reveals that Iran is beginning to develop a nuclear powered submarine. On a more substantial level, last December they announced they had put another three of their Ghadir class submarines into service. While the nuclear powered sub project is a mirage, the Ghadir is real, as there are 19 of them in service.
What Iran does not issue press releases about is the stuff that doesn't work. Take, for example, the 400 ton Nahang class sub. This was to be the successor to the 120 ton Ghadirs. Alas, one Nahang entered service six years ago and none followed. The Nahang seemed to spend most of its time in port, full of technicians, or in dry dock, partially disassembled. A successor to the Nahang, the 1,000 ton Qaaem has yet to be finished after five years of effort. Moreover, the Qaaem, unlike the other Iranian built subs is not a mini-sub that can operate anywhere in the generally shallow Persian Gulf. For example, the three Russian built Kilo class subs Iran has are so big (2,300 tons) that they can only operate in about a third of the Persian Gulf. That makes them easier to find and destroy in the Gulf. That explains why Iran is increasingly sending its Kilos outside the Gulf.
Meanwhile, the successful Ghadir is another example of Iranian resourcefulness in the face of embargoes. Since 1996, when Russia agreed to stop selling them submarines, Iran has been working on their own designs. After ten years of trial and error they produced the 120 ton Ghadir (Qadir) class vessels in 2005. Iran claims to have a fleet of 19 of these small diesel electric subs and no less than four have been shown together and photographed. The Iranians are not releasing specification sheets to anyone, but Ghadirs look very similar to the Italian Cosmos SX-506B submarines that Columbia has operated since the 1980s. The 100-ton SX-506Bs are only large enough to carry commandos and mines. However, released news footage shows what looks like to be two torpedo tubes on the Iranian Ghadirs. The Iranians claim that the Ghadirs carry torpedoes.
It should be remembered that Cosmos exported a number of larger vessels to Pakistan in the 1990s. Dubbed the SX-756 they may have been the design basis for the Ghadir. It should also be acknowledged that the North Korean Sang-O class submarine closely approximates the Ghadir type. In 2007, North Korea gave Iran, outright, four of its Yugo-type midget submarines. These Yugos were well worn 90-ton 21 meter (65 foot) craft but Iran accepted them all the same. Taking them apart taught the Iranians much about how to design and build mini-subs.
Iran took the big leap in the early 1990s, when they acquired three Kilo 877/636 type diesel electric submarines from Russia. The 2,300 ton Kilos are long range subs capable of operating throughout the Indian Ocean (from South Africa to Australia). The Kilos have six 533mm (21 inch) torpedo tubes and 18 torpedoes (including one or more Shkval rocket torpedo) or 24 mines. Very similar to the world-standard diesel submarine, the 1800-ton German Type 209, the Kilo is a formidable foe and can stay at sea for up to 45 days, which makes it capable of long range patrols.
All this Iranian submarine activity has spurred the U.S. to develop new tools and techniques for detecting small subs in shallow waters. The Americans have not released results of tests against NATO mini-subs. But that is to be expected. You save that kind of surprise for the first few days of a war.