How to keep your ship from sinking right away. A small guide to bouyancy! Lots of people seem to ask "Why does my ship not float?" and here is the answer.
Buoyancy
In order for something to float in Stormworks it has to have an enclosed volume of air.
Lets say we build a boat shaped like a shoebox but without a lid. In other words our ship has a bottom and four walls but no 'ceiling'. It will NOT float because to the game there is a big hole in our shoebox, namely where the 'ceiling' (or shoebox lid) should be. So the air inside is not completely enclosed and our ship will not float, no matter how many pumps we install.
If we put the lid on the shoebox it will float, no pumps needed. You can even access that enclosed space by installing a door- or hatch-block, but make sure to put it above the waterline. Otherwise you risk flooding the enclosed space when you open it. If that happens pumps can be used to drain the water. Of course they can be used for flooding as well.