I haven't got back to the forums for a couple days which is why my response is delayed. To touch on a few points.
There were many battleships in service throught U.S. conflict before 1992. There was one operational in 1952 for the Korean War. As well as in 1968 in vietnam (oops on me), and there were ones in service during 1984-1991 ( Operation Just Cause occured 1989, they they did not serve officially in the conflict). They were completly decommissioned in 1992 for the whole. No Battleships serve in todays military. The Iowa and New Jersey have been donated to the states that hold their name for historical viewing and only the Missouri and Wisconsin are still collecting mothballs in a decommissioned dock. Remember decommissioned means they can come back if we need em'.
Its true they are heavy (leads to quicker sinking) and slower but they still represent a significant force in the world.
However I don't have to explain my case, I'll let the Navy do that for me. I grabbed this off the U.S. Navy's homepage at
Http://www.Navy.mil
the actual page is
http://www.chinfo.navy.mil/navpalib/ships/battleships/bbhistory.html
Battle Ship History, U.S. Navy.
--------------------------------------
During this time many of the battleships were mothballed or sold as memorials to the various states whose names they carried. Only a few of these majestic ships remained in service until 1948 when the last active battleship was redesignated a training ship and the Battleship-Cruiser Force, U.S. Atlantic Fleet, was renamed Cruiser Force, U.S. Atlantic Fleet.
The battleships returned during the Korean Conflict (1950-1953) for use in shore bombardment. The Battleship-Cruiser Force, U.S. Atlantic Fleet as a TyCom was resurrected on Oct. 15, 1952. With the Korean armistice and by 1957, the battleships began being decommissioned again. By Mar. 8, 1958, there were no active battleships and the type command reverted to Cruiser Force, U.S. Atlantic Fleet.
A final hurrah
USS New Jersey (BB 62). was brought back into service in 1968 and served as a gun platform off the coast of Vietnam. Her nine 16-inch guns could throw a 2,700-pound projectile more than 20 miles. The ship was again decommissioned in 1969, but was recommissioned in 1982. She was modernized, receiving an installation of 16 Harpoon missiles, with a range of about 60 miles, and 32 Tomahawk missiles, with a range of about 500 miles.
In May 1984, the United States Navy began recalling the remaining Iowa-class battleships for active duty, following modernization and updating. These weapons platforms were needed for an expanded 600-ship Navy to lead battle groups and help establish the U.S. naval presence around the globe. The 600-ship Navy was never realized and, instead, defense budgets continued to shrink. For this and other like reasons, USS Iowa (BB 61) and USS New Jersey (BB 62) were decommissioned for a final time by early 1991.
The invasion of neighboring Kuwait by Iraqi dictator Sadam Hussein in February 1991 postponed the fate of USS Missouri (BB 63) and USS Wisconsin (BB 64). The big guns of the two battleships hammered at land targets in Kuwait in support of the Allied ground offensive. Iraq agreed to a cease fire agreement on Feb. 28, 1991.
But the cost of operating these ships, the labor-intensive manning, and the more modern, more powerful cruisers and destroyers of today's Navy led to their final decommissioning as well. The last battleship on active duty was USS Missouri (BB 63) decommissioned Mar. 31, 1992. In the 21st century, there are no battleships in the United States Navy.
-----------------------------------------------------
However the Battleship remains a significant power of the seas, and by the way, she was named the Queen during the Second World War for her size and her ear popping power. The reason we didn't use Battleships in the North Atlantic is the Royal Navy had a significant presence there already, the U-boat menace made a significant problem for the battleships slow pace, and the largest need for sea power was in the pacific where the greatest fleet battle's to date have occured. So it was more a matter of circumstance that the battleship didn't serve in the U.S. Fleet, Atlantic Command then it was a problem of tactical capabilities.
So if you want a realistic Battleship this is my opinion...
Battleship
Attack - Medium, similier to Destroyer attack. It was the meanest ship in the 40's after all.
Defense - Low, needs to be escorted.
Speed - Slow, will slow down your escorts.
Bombard - Heavy, best in the game. Even better then cruise missle's. (don't start me on cruise missles

those i've studied fairly extensivly)
Maintnence/Cost - Maintnence should be large, probably the most expensive to upkeep. Cost should be a lot, perhaps 25 - 30? not sure but a lot.
Perhaps later you can have an upgraded version of the Battleship (say call it, the Modern Batlteship?) with the capability to carry one cruise missle and a faster speed, but not a lot faster. It would cost a lot more to build but the upgrade of previous Battleships would be relativly cheap. Near same state except for perhaps a heavier bombard by a bit.
This I think would limit it to its role while still keeping a realistic look at it prowess on the high seas. Whenever the U.S. has entered a conflict with a powerful enemy on land or sea the battleship will have a role. How badly we need it to fill that role versus risk of damage makes that a concept to be decided but I garuntee if we had something to pound on the ground or from range at sea you'd see a battleship. I wouldn't stop its ability to be produced at 1950, we still have that ability. We just don't want too. If some nation could afford it and want to continue to produce them after 1950 I think they should be allowed in game, we haven't forgotten how to build them. As I said, we just don't want too.
Let me summerize the support ships it would at least require. This is all valid information that you can also look at, at the Navy's site.
These are all modern warships.
Submarine's
---------------
Attack Submarines - The SeaWolf class and the newer and more improved Virginia class submarines are your submarine/surface ship hunters.
Attack - Medium, around the size of the destroyer.
Defense - Low medium, higher then low but able to defend itself. They go up quick sometimes.
Speed - As fast as most ships, they can cruise at 25+ knots. The normal for a fleet is 20.
Can carry cruise missle's only and only one since there is limited space.
Cost/Maintnence - Cost should be a bit more expensive then its current setting. Maintnence should be normal.
Ballistic Missle Submarine - The Ohio class is the U.S. ballistic missle submarine. Its role fills the void for submersible strategic missle placement.
Attack - Low, not an attack submarine.
Defense - Slightly lower then the Attack due to the submarine's obvious stealth and evade capabilities.
Speed - Same as Attack submarine.
Can carry 4 to 5 tactical missles. It cna truly carry 24 trident class thermo nuclear missle's but that's just insane for this game.
Cost/Maintnence - Same as attack sub.
AEGIS Cruiser
-----------
Cruisers with the AEGIS combat system onboard - They are your BFC or Battle Force capable sea ships. In modern times your most significant power at sea to sea combat.
Attack - Biggest attack at sea.
Defense - Good defense, able to take on any ship.
Speed - Faster then the sub or battleship, near same level for destroyer. it cruises at 30+ knots.
Bombard - Second best in game, after the battleship of course

.
Cannot carry cruise missle's. It carries SM-1 or SM-2 missles but these are defense weapons alone and should factor into its defense and not offense. They are surface to air missle's. Therefor... Turn on Interception in air power make this range one or two squares. I'd lean towards two.
Cost/Maintnence - Cost should be heavier then tis current setting. Maintnence should be the smae.
P.S. The weapon you speak of that encompass's ship to ship missle weaponary is not a cruiser only weapon. The Harpoon missle, which is the base for ship to ship combat today, is for fleet wide use meaning any ship outfitted with the proper battary could have one. This is so wide spread that I believe it shouldn't create a factor in combat as it cancels itself out. Otherwise you couldn't properly represent sea combat in CivIII since everything would have a phenomenal attack rate, even carriers and battleships (yes BB's carry Harpoons). There's even more air to shi and helicopter to ship missles so we can't represent sea combat through guided ordinance.
Destroyers
--------------
Destroyer - Normal destroyers are your submarine hunters carrying a small ability to bombard. They fill the role of specialized submersible defense.
Attack - Medium, enough to take on a submarine.
Defense - Medium, enough to defend against a sub.
Bombard - Low
Speed- Fast, up to speed with the cruiser. It has a speed of 30+ knots.
Can see submarine's on.
Cost/Maintnence - Cost should be a little less then cruiser. Maintnence should be normal.
Guided Missle Destroyer - The missle destroyer is what delivers your cruise missle capacity. No other ship has its ability to deliver as many Tomahawk missles in such quick succession.
Attack - Low, cannot attack something very easily.
Defense - Low, needs support for protection.
Bombard - None
Speed - Fast.
Should have anti air capabilites that exceed the Cruisers range.
Should be able to carry 5 cruise missle's, maybe 6 but that sounds over generous.
Cost/Maintnence - Cost should be same as cruiser due to the fact it has AEGIS sytem onboard. Maintnence should be normal.
Modern Frigate
-------------------
Not needed. They simply fill a role very similier to their Destroyer counterparts but with less growth capabilities and increased toughness versus actual hits taken. They are versitile and tough ships but don't offer a different type of combat role for them to represented in CivIII.
Other then that there is the Carrier which wouldn't provide support for a battleship but rather have its own battlegroup. Of course I have an opinion on that as well.
Carrier
---------
Conventional Take Off And Landing Carrier or CTOL Carrier.
Attack - None
Defense - Low
Speed - as fast as the crusier, it can cruise at 30+ knots as well.
Can carry 6 aircraft, maybe 8 due to the fact the Nimitz class can carry a compliment of 85 aircraft.
Cost/Maintnence - Cost should be heavy, they cost 4.5 billion to make. I'd say the second most expensive sea unit after the battleship. Maintnence should be higher then the norm but not as high as the Battleship.
The STOVL/Rotary propelled aircraft carrier. The U.S. has the most significant force of these as well in the Kitty Hawk Class Aircraft carrier. Able to slightly out class the closest Russian and European versions by aircraft launch and hold abilites.
This is llllllllloooooooooooonnnnnnnnngggggggggg, I know. However I enjoy a flex of resources from time to time. This is straight from the source with links and all so enjoy looking up the info, I know you all will find something interesting to learn about. Don't rely on Encyclopedia's, they are written by a group of people who can't possibly know about everything the Encyclopedia is to encompass with an indepth knowledge. Especially computer encyclopedia's, Half - truths and missing information run wild in them, though they usually don't (seeing your quote there are obviously exceptions) out right lie. Microsoft does it again right

.
The U.S. Navy is the most powerful sea power in the world. Russia's capabilities lie in their submarines and in no other catagory can any nation or state even challange American Military sea power. So they should be the basis for all CivIII sea power since most russian heavy sub equipment is behind closed doors to those in higher positions of the countries that have the ability to learn about them.