http://www.combinedfleet.com/okun_biz.htm
Nathan Okun is probably the most widely respected researcher on naval large caliber weapons and armor at the present time. His take on the different protection schemes for battleships of World War II. (You can have permission to skip the boring mathematical formula he includes to prove his points. As if wargamers care about math!)
Oh, boy. That looks like great stuff, but I'm not up for a read like that this early on a Saturday.
the Naval Institue Press has a great series covering each specific US type. expensive books but fun reading.