There are two ways to get steel: the Business Office lets you trade any four resources for one steel, and the Steel Mill converts iron (and lots of energy) to steel. The Business Office isn't used much, but it actually looks better if you want to build one steel ship and have a lot of otherwise useless tiles. In particular, Feedlot/Business Office makes for a good combination; you'll gain two cows at every harvest, slaughtering six at a time for three hides, so you are likely to have nine hides by the time you want to build steel ships.
Note that I am counting total actions here; you can't use the same building twice in a row, and the building that you need might be occupied, but you can usually find something else useful to do in the meantime.
Steel ship with Business Office:
Business Office: five resources for one steel and one charcoal
Business Office: five resources for one steel and one brick
Wharf: use one charcoal, build steel ship
Net after three turns: one spare brick (if not needed to modernize the wharf), ten hides/fish/etc used. Entry fees are 2 francs and 2 food.
Luxury liner with Business Office:
Business Office 3x: 15 resources for three steel, one charcoal, and two brick
Wharf: use one charcoal, build luxury liner
Net after four turns: two spare brick, 15 hides/fish/etc used. You'll probably have to give up a turn worth of junk to get to 15 resources. Entry fees are 3 francs and 2 food.
Steel ship or luxury liner with Steel Mill:
Colliery: take four coal
Cokery: coke four coal, gain 4 francs
Ironworks: take three iron
Steel Mill: use two coke, convert three iron to steel
Wharf: use one coke, build luxury liner (or steel ship and save one steel for shipping)
Net after five turns: one spare coke, 4 francs gained, one spare steel if you built a steel ship. Entry fees are 4 francs and 4 food.
The Steel Mill is better if you want two steel ships.
Colliery: take four coal
Cokery: coke four coal, gain 4 francs
Ironworks: use one coke to take four iron
Steel Mill: use two coke, convert four iron to steel
Wharf: use one charcoal, build steel ship
Wharf: use one charcoal, build steel ship
Net after six turns: one coke left but two charcoal used, 4 francs gained, two steel ships. Entry fees are 4 francs and 6 food, which is 2 francs and 3 food per ship.
Note that I am counting total actions here; you can't use the same building twice in a row, and the building that you need might be occupied, but you can usually find something else useful to do in the meantime.
Steel ship with Business Office:
Business Office: five resources for one steel and one charcoal
Business Office: five resources for one steel and one brick
Wharf: use one charcoal, build steel ship
Net after three turns: one spare brick (if not needed to modernize the wharf), ten hides/fish/etc used. Entry fees are 2 francs and 2 food.
Luxury liner with Business Office:
Business Office 3x: 15 resources for three steel, one charcoal, and two brick
Wharf: use one charcoal, build luxury liner
Net after four turns: two spare brick, 15 hides/fish/etc used. You'll probably have to give up a turn worth of junk to get to 15 resources. Entry fees are 3 francs and 2 food.
Steel ship or luxury liner with Steel Mill:
Colliery: take four coal
Cokery: coke four coal, gain 4 francs
Ironworks: take three iron
Steel Mill: use two coke, convert three iron to steel
Wharf: use one coke, build luxury liner (or steel ship and save one steel for shipping)
Net after five turns: one spare coke, 4 francs gained, one spare steel if you built a steel ship. Entry fees are 4 francs and 4 food.
The Steel Mill is better if you want two steel ships.
Colliery: take four coal
Cokery: coke four coal, gain 4 francs
Ironworks: use one coke to take four iron
Steel Mill: use two coke, convert four iron to steel
Wharf: use one charcoal, build steel ship
Wharf: use one charcoal, build steel ship
Net after six turns: one coke left but two charcoal used, 4 francs gained, two steel ships. Entry fees are 4 francs and 6 food, which is 2 francs and 3 food per ship.
