Currently my line of battle is 78 super-dreadnoughts, 131 dreadnoughts, 43 pre-dreadnought battleships, 78 battlecruisers, 51 heavy cruisers, 213 light cruisers, 550 destroyers, 409 submersibles, and 23 airships. I am building or have ordered 64 super-dreadnoughts, 61 dreadnoughts, 117 battlecruisers, 205 cruisers, 861 destroyers, 1,672 corvettes, 2,050 submersibles, and 124 airships, with the expansion scheduled to be completed by 1915.
Uh I've had two and they have been quite minor. Mostly involving reorganization, not a complete rebuild.