What speeds can a sub go before making detectable noise?

[ET2SN]

Originally Posted by PurpleCow

In real life do fast attack subs travel at very slow speeds or do they normally cruise around at 20 knots and still remain quiet. I guess I assumed that the fast the props turn the more noise the sub would make.

What about boomers? Do they cruise at very slow speeds (5 knots) because they are trying especially hard to be silent?

In real life, fast attacks travel fast when they need to get somewhere or evade something in the water. Don't get confused with speed. When a fast attack is on station they want the optimal sonar environment for the sensors. Moving fast means your sonar is trying to listen to rushing water which means you aren't hearing the important stuff. Fast attacks also need to be able to move so they can attack distant contacts. Your high tech sonar isn't worth beans if you can't get within your wep's range on time.

Like I wrote before, Boomers are Boomers. They are completely different classes of subs with their own mission and tactics. Since they are much larger than a fast attack, they tend to be more difficult to control. They also need to be as quiet as possible for as long as possible, since their mission is to remain undetected until they launch their missiles (which, ironically, means their mission failed) or return to port.