AA house rules

I'm not convinced that you can turn 9d6 against aircraft into 9d6 against ships. Sure, the 6-in DP guns were used against ships, but this is already accounted for in secondary armament, which is typically up to about 6d6 (you'll see larger values for secondary armament, but not on 5-inch guns generally AFAIK). A chunk of the 9d6 for antiaircraft are coming from 40mm or smaller caliber antiaircraft guns. These are not suitable for ships and will do nominal damage to ships except possibly patrol craft.

Take the Atlanta for example.
Main 6,6,5
AA 8

The main are coming only from the 6-in DP guns.
The massive AA value has to be accounting for the 6-in DP guns, as well as the assorted smaller antiaircraft armament.

Thus your house rule give Atlanta a double use of their DP guns for ships as well as a buff on the second use.

Same with any of the North Carolina, South Dakota, or Iowa-class battleships (plus some of the standard-types in their post-Pearl Harbor refits). You get bristling with guns for two uses of their secondaries and then your house rule gives them a third use of their secondaries with a 2d6 buff.

Lots of ships factor aa into thier mains or secondary values. Bear inmind that rhe sectors are 5000 yards. How much penetrating power would you get at that range with light AA

Really you shouldnt be able to make both aa and surface attacks with those weapons. But w@s is slimmed down for soeed abd simplicity.

It is interesting as a SA idea

Raking Fire: once per game, if this ship did not make an anti-aircraft attack this turn. You may roll your anti-air attack against a local enemy ship. This attack only hits on 6.