Is this some sort of joke about her screws? I don't get it.
yep, her and Wash had vibration issues stemming from their redesigned hulls and propulsion system that were so bad it made her rear rangefinder useless at top speed. She spent most of 1941 trying on different types of screws and prancing around New York Harbor giving her the nickname "Showboat" Fun fact, she never actually achieved her designed top speed of 28 knots in her life.
There's actually a very interesting (for engineering types) report on this from the David Taylor Model Basin out there. Lemme see if I can find it again... there we go! "Analysis of Vibration in the Propelling Machinery of the Battleships
North Carolina and
Washington (BB55 and BB56)," by R.T. McGoldrick and W.F. Curtis. Available for free download from MIT's library as a PDF at
Analysis of Vibration in the Propelling Machinery of the Battleships North Carolina and Washington (BB55 and BB56) : MIT Libraries
116 pages of the details of the problem and everything done to try and solve it. The vibration problems were largely solved at high speed by December of 1941, with modifications to the machinery, changes of screws, and (finally) external bracing of the aft fire control tower, but BuShips never considered the problem fully solved, as both ships were decommissioned in 1947 while still having unacceptable vibration in the 17-20 knot range.
According to Friedman,
Washington did make 28 to 28.2 knots in a full-power trial on 1 December 1941, and both ships were considered good for 26.4 knots at full load, 27.3 knots at designed trial weight of 42,100 tons in 1945;
Ships Data 1945 showed them as being good for 27.6 knots at 42,000 tons, while BuShips set a maximum desirable displacement limit for them at 48,000 tons (as all US warships were rapidly gaining weight at the time). Given that the Iowas were designed for a 33 knot trial speed and considered good for 31.4 sustained in the same issue of
Ships Data, and that the performance of WW2 US cruisers was quite disappointing (usually targeting 34-35 knots, but only getting about 32), I'd say that's close enough to say that the NCs met their design speed.
So one thing I stopped to consider for a bit is just how fucked the timeline is going to end up being. We all know that going back in time in general is usually bad enough, and with how much Thompson has fucked around already he's probably already caused catastrophic damage farther down the line like causing the Cubs to win every world series between 1960 and 1993, but we have at least two people fucking around with the past and generally breaking shit. If we involve every major player of the war, that's five people running around breaking time. I wonder just how fucked the timeline will end up being down the line.
If Thompson's memory is good enough, one possible result is that he'll manage to get the Alaska-class cruisers into the same "national asset" protection status as the Iowas had (and maybe get the Navy to go ahead and do that final 5% of construction to complete
Hawaii in the process), as it was realized in the 80s that the Iowas were really too
big for the role we were reactivating them for, and since CG/DDG-type ships were a bit too small, the Alaskas would have been pretty much a perfect fit, providing the same missile capacity (and much of the heavy bombardment capacity) as the Iowas, but at a significantly reduced operating cost.
