Wanna drive a specific boat of a class?

[The Bandit]

Originally Posted by LTJGBeam

A little more detail added to Carthaginain's post:

688 - Original LA Class, standard boat, 4 tubes amidships, fiberglass sail, AN/BQQ-5 SONAR Suite and TB-16 Towed Array.

688 Flt II - adds VLS tubes, TB-23 Towed Array, Anechoic Tile, otherwise similar

688 Flt III/688(i) - VLS tubes, AN/BQQ-10 SONAR and TB-29 Towed Array, Anechoic Tile, External 6" Countermeasures pods in addition to the internal 3" countermeasures, bow planes instead of fairwater planes, under-ice capable.

Incremental quieting and fire control improvements made throughout the classes and flights. Biggest improvement in the Flt III is the AN/BQQ-10 which is a significant improvement of the AN/BQQ-5. How much I can't say, as I signed an NDA when working at SUBSCHOL, New London. Don't want to pay the 2.5 Million Dollar fine and spend up to 25 years in prison.

From what I remember BQQ-10 and TB-29 were back-fit items that didn't appear until the late 90s / early 2000s and "I THINK" was also installed on some of the refueled Flt I boats at around the same time. Its possible some of the last 688Is like Cheyenne or Greenville had it right out of the gates but I'm not sure.

Somewhat important to point out as well because it often gets overlooked, you could say there were 4 main variants of the 688, all the ones you mentioned plus what you could call "flight 0". The initial 688s (from 688-699) were a little different. They didn't have a retractable towed array, nor did they have the Mk117 digital fire control, so IIRC no Harpoon and definitely no Tomahawk capability. Still, by the early-mid 80s they had all been refit to the same "Flt I" standards as the rest of their class.

Two more things about Flt II. They were the first boats to come from the yard with anechoic tiles fitted, and they also used a more powerful nuclear reactor that was good for the lifetime of the boat. USS Providence and her sisters (which are soon due for retirement) have never had to be refueled in their 30+ year lifespan.