French submarine builder DCNS is now selling a new coastal boat, the Andrasta class. This is an 855 ton, 153 foot long sub, with a crew of 19 (plus 8 passengers, usually commandos). The boat can stay underwater for up to five days. Surfaced, it can travel up to 5,400 kilometers, at slow (170 kilometers a day) speed. There are sufficient supplies on board to keep the boat out up to 30 days. Most missions are expected to be more like two weeks. The boat has six forward firing torpedo tubes, which can also carry mines or anti-ship missiles. There are no reloads, all the weapons are stored in the torpedo tubes. There is a special chamber for letting divers exit the boat while underwater.
The Andrasta is similar in size to the 769 ton German World War II Type VII boat, which was the most widely used (700 built) sub during the Battle of the Atlantic. The Type VII was longer (220 feet) and thinner, and didn't have all the electronics of the Andrasta, or all the automation. Thus the Type VII had a crew of 50 and carried 14 torpedoes (used in five tubes), plus an 88mm deck gun (and 220 shells). Moreover, the Type VII could only spend about one day underwater, although it had a surfaced range of 15,000 kilometers.
The Andrasta is built to be quiet, and use its powerful passive sonar to detect surface ships or subs, and use its heavy torpedoes to destroy them. The Andrastas cost less than $200 million each (half the price of most normal size subs), and are attractive boats for nations wanting to use submarines mainly as defensive weapons.