According to the Wikipedia article (I'm really not in the mood to research and document more efficiently, however all material there is sourced if you want to put in the due diligence) the USS Texas (the last remaining Dreadnought battleship, and one of the primary battleships supporting Omaha and Utah beaches in Operation Overlord) was indeed armed with 14" guns. These guns had a range of 13 miles (11 nautical miles, 21 kilometers) and had a rate of fire of 1.75 rpm.
I'm tired, so I haven't fully researched the blast radius of these shells, but they are immense. Just a suggestion, but rather than having to man the turrets, would it be possible to link them to the Commander's area attack? I am thinking that perhaps the Commander (who, real world would have a direct line to the offshore support) should get a salvo of battleship fire every 2-5 minutes, but with a limited number of impacts, and if possible a limited amount of ammunition. This would give strong incentive to play in the Commander role and would still require Squad Leaders to request the fire. This would also alleviate the need for a dedicated naval gunnery squad and allow more US players to hit the beach at one time.
In terms of realism, the BB should have no problem hitting the entire map, but I think this is probably overpowered in an implementation where the guns are individually manned and controlled. By implementing the Commander's area attack mechanic the weapons can only be targeted by Squad Leaders and fired by the Commander. Additionally, it should be doable to make the weapons actually fire, muzzle blast and all. I remember the Artillery attack in vBF2 triggering an animation and weapons fire from the physical artillery in the game.
The source for a large chunk of this info, documentation-wise is below. I grew up minutes from where the USS Texas is anchored, and spent a large amount of my childhood wandering its decks and learning about the ship. Some of this stuff may be faulty memory on my part, but to be perfectly honest, I am too tired to go research any more tonight. If someone else wants to take the reins, be my guest.
![Wink ;)](./images/smilies/icon_e_wink.gif)
http://en.wikipedia.org/wiki/USS_Texas_(BB-35
On a side note, any possible chance of naming the supporting ship the USS Texas?
![Very Happy :grin:](./images/smilies/icon_e_biggrin.gif)