I'm looking for an "open" computer naval wargame

I want to be able to fight a campaign with the ships that we designed. It may not be easy to do, but I would like to be able to import user ship definitions and run battles with them. I really would like a game with a campaign map and with detailed regional and tactical maps. I want to be able to game with 30 or 40 ships on a side, and maneuver by divisions or squadrons. Doesn't that seem like something that we would want? What we really want is to be able to accommodate large numbers, so that we could refight the battle of Jutland with real numbers of ships. For sailing naval warfare, I can create my own ship definitions and scenarios, and fight battles with Privateers Bounty. Sadly, it can't accommodate really large numbers of ships, so we can't fight the large battles with the actual numbers of ships. Something like this is needed for the 1903-1927 period (this is my own time period of interest).