Where do you find them? I have the blast furnace one, but there are a ton more and I have no clue where to find the blue prints to unlock them for purchase. Thanks!
You can find a vendor on your docks who sells ship upgrades, though you may need to progress a bit before they're available for purchase. The initial quest line, however, will give you the Blast Furnace upgrade which you can use on one of your newly created vessels.
