I am pretty sure there is a problem with the evolving naval techs and ship construction. When a tech is discovered that allows a new ship class/type to be built, it is not entirely clear what type of ships can be built out of the available production pool. This is what tricked some of the players in our MP game, who did not realize they could build the newer ships, since the ones in the pool still had the image/icon of the previous type. When those older ships were placed on the map for construction, the new class appeared on the map. The problem at hand is the cost to build that new ship is for the older model (the one chosen in the production pool) and not the new one (that is actually appearing and being built on the map). I now realize this is going to be a major problem as the game goes forward, since the newer models of ships are going to require much larger amounts of material to construct.
I did not know the difference in cost between the old wooden screw battleship and the newer ironclad battleship, because I never received the proper icon for that ironclad model in my production pool. In fact, I still have not received it and do not know which tech places the proper icon in the pool. I did not realize how big this problem is going to be until I got my most recent advanced tech. In our MP game, I discovered and can now build the 1875-1895 light cruiser. My ironclad corvette icons in the pool have switched over to the new light cruiser icon and I can see the proper cost for building those ships. They are definitely more expensive, especially in steel. However, I still have a lot of the wooden corvette icons that can be built and when I place one of these on the map it turns into the light cruiser, but at the very cheap cost of building the old wooden corvette. The difference is so big that I cannot, in good conscience, build new light cruisers at the old wooden corvette prices. This would definitely be cheating.
Unfortunately, I still do not know the true cost of an ironclad battleship and I did not realize this could be a potential problem at the time I built a lot of them. I do not believe, however, the costs can be very much different than the wooden screw battleship. At least not as great as the leap to the steel ships is going to be.
Here are the two possiblities causing this problem as I see it:
1. The game is not upgrading all the available builds in the pool, for a particular type of ship, to the new tech level when it is discovered
or
2. The game is mistakenly allowing the more advance class of ships to be built when the old tech icon is chosen and placed on the map for construction
I personally believe that all allowable builds should be upgraded to the new tech (issue #1 above) and the old ones removed so they cannot be built, but I do not know what the devs had intended. I hope this can be fixed quickly, so that we are all paying the proper cost for our new ships.