I deleted Naval Construction Yards. Now, I can't buy navy. It doesn't say anything that I need it to buy navy.
"You do not have enough infrastructure, land, technology, money, or improvements to purchase navy vessels at this time. To purchase the most basic navy ships you need at least 2,000 infrastructure, 1,000 land, 200 technology levels, at least $460,933 and either a Drydock or Shipyard improvement. Additionally, each vessel type has an infrastructure support limit that will restrict the number of each type of ship that you can purchase."