Sea block is intended to be played with a full set of Bob's and Angel's mods. These are not all listed as dependencies, so installing just the bare minimum set of mods needed to get it running will give an untested, possibly unbalanced subset of gameplay. You'll be missing important mods like bobpower (more efficient boilers) and bobassembly (faster assembling machines), for example.

I distribute the recommended set of mods for playing sea block over in the sea block pack forum thread. Follow the installation instructions in the first post to get everything installed.
If you'd rather install everything through the in game mod browser then the same set of mods can be obtained by installing my sea block pack mod and dependencies.

Error when creating a headless server

Issue: Getting the following error when setting up a game on a headless server

0.000 Error Util.cpp:83: "coal" is not a valid autoplace control name.

Solution: In map-gen-settings.json clear the autoplace_controls section

"autoplace_controls":
{
  "enemy-base": {"frequency": "normal", "size": "normal", "richness": "normal"}
},