Nuclear-powered submarines generate, on the whole, more noise than their AIP counterparts when submerged. The primary reason is that plant noise is a constant due to the need to pump coolant through the reactor unit. The AIP submarine does not generate power through a reactor, and does not have to worry about that sound source. Therefore it is safe to say that modern conventional submarines are 'stealthier' than their nuclear counterparts.

The tradeoff is that nuclear submarines have far greater underwater performance in speed and, generally, depth. They also have unlimited submerged endurance, as they also generate their own oxygen.

AIP is the ultimate form of stealth i guess, but endurance wise it's still in its infancy, this technology is hard to master..

But we agree on subs being the stealthiest weapon around, diesel subs with snorkel offer the best thing next to AIP and most conventional subs are still diesel powered, AIP is offered as an upgrade for many boats and offered by a variety of manufacturers around the world as Wiki says, didn't know the technology was in that state at the moment, interesting thing:)

Yes. I think that, ultimately, AIP is the future of submarine design and all submarines will be of the AIP variety as soon as the technology matures to allow for greater performance.

Ähem - food...?

They fire a harpoon trough the torpedo tube and cut the whale up in the airlock

Endurance is not the only limitation of AIP subs, performance as well. No AIP sub has ever exceeded 5 knots. At that speed, one can`t do much, unless one has accurate information of an enemies movements.

ELINT. Commando operations. And sitting in ambush in water straits, naval bottlenecks - there are so many possible scenarios, also consider those places where a big SSN cannot operate - extremely shallow waters for example.

Also, I doubt that speed limit. The 212 for example did the trip from Eckernförde to Rota in 2006 (while staying submerged for two weeks), and plotting a simple course through the English channel and straight over the Biskaya Bay, not following the coastline that is, gives you a minimum range of around 2000 nm. 2000 nm in two weeks has you ending up with an average speed of 6 knots. Now, the 212 has an electric engine which gets the electricity it runs by either from the boat's Diesel, or the fuel cells. So the critical factor is the fuel cells' capacity. The faster you drain them, the sooner they run dry. But I think in principle the engine is capable to reach maximum speed no matter whether using the Diesel or the fuel cells - since it always comes down to electricity as fuel. 6 knots possibly hints at the economical best compromise between speed and durability of the fuel cells. But the public data sheet indeed lists 20 knots as maximum speed when submerged.

The real limits of course are kept secret.

The Swedish Gotland boats use a Sterling engine with AIP capability. Their maximum speed when submerged also is listed with 20 knots, public data.

I'm eager to learn about the A26, their new improved Gotland class that is under construction. The Gotlands and 212s probably are the closest rivals to each other in their league.

Concerning usability, one should not see SS and SSN as contradictory, but complementary, I think. Each class has things it can do better than the other, and each class has characteristics where it is inferior. What boat would you choose in the Baltic? And in the middle of the Pacific? And never forget - a 209 sailed from Germany into the Gulf of Mexico, and back.

No one said an SSN has to be huge. Just look at the old Skates, those were roughly the size of an Fleet Boat. :salute:

LOL, so the Americans went to all the trouble of copying Nazi designs, passing them off as alien spaceships, for nothing!

The Skipjacks were only slightly larger than todays SSKs. Between 60-70 meters long.