AA#1. Throw weight equals (rate of fire * number of barrels * weight of shell). Calculated from information in Campbell.
AA#2. This particular configuration represents Tirpitz at the end of her career. Note, too, that the 37mm gun carried by Bismarck (and most German ships until late in the war) was the 37mm Flak M42, which had a very slow practical rate of fire (listed at a nominal 160-180 rounds/minute) due to the necessity to change the 6-round clip between each burst.
AA#3. This particular configuration comes from Duke of York in April, 1945.
The really awful truth here is that I'm being generous in terms of overall effectiveness for the DP guns. With proximity fuzed ammunition, the Allied batteries were perhaps five times more effective than their Axis counterparts. When you adjust for inferior fire-control (vis-a-vis the US Mk 37), lack of RPC, and so on, you could easily get a Secondary: Anti-Aircraft rating that looks more like this:
AA#4. Leaving Iowa as a '10' means everybody else (except Richelieu) gets adjusted downwards, sometimes dramatically so. The reasons for adjusting are mainly due to fire control. Iowa had tremendous fire-control, RPC, and radar for her mounts at the end of the war. I arbitrarily subtracted from the other ship's ratings (except Richelieu) for lack of radar, RPC, and so on.
Secondary Armament: Anti-aircraft: The Harsh Score
Yamato
Iowa
Bismarck
Richelieu
King George V
Vittorio Veneto
South Dakota
Raw Rating
2.5, 5.5
10
5
2
6
2
10
Adjusted Rating
1
10
1
1.5
5.5
.25
10