The new class of submarine is significant for several reasons. Firstly she is much larger than previous Iranian made boats and can carry at least four torpedoes. Her length is estimated to be 48m and her beam about 4m, giving her a displacement in the region of 300 tons.
Secondly she appears to be a truly indigenous design (there is a suggestion that it might be a Chinese design but that is unproven). The main Iranian built submarine type to date has been the IS-120 'Ghadir' Class, which is really the North Korean designed MS-29 'Yoneo'. The Yoneo is a potent and proven midget submarine armed with two 533mm (21 inch) torpedoes, but she is much smaller and consequently has limited endurance. In fact the Yoneo is about half the length and a quarter of the displacement of the Fateh. Earlier truly indigenous submarine designs appear to have all been experimental or at best only limited successes not put into series production (e.g.Nahang Class). Whether the Fateh is also a one-off design has yet to be seen, but outwardly she gives the impression of being a tactically useful unit. Her size also gives her the possibility to carry weapons with more significant negative buoyancy, for example the 'Hoot' supercavitating rocket-torpedo (a weapon much publicised but yet to be evidenced in service)
The Fateh is about 48m long with a generally conventional hull form with blunt vertical bow and tapered stern. This is similar to the German Type-206 series deigns and former-Yugoslavian 821 (Heroj) and 831 (Sava) classes. It is difficult to say whether she carries any reloads for her four bow torpedo tubes, but from the distance between the bow and the sail it seems probable that she does. A useful load of about ten torpedoes or twenty mines seems a reasonable assumption.
Photo and satellite analysis suggests that the boat is about 4m in diameter (initial estimates were as much as 6m, which would be a much bigger boat). This is enough for two floors, as confirmed by the leaked plans.