The ship got under a port and I can't click on it to move it.
Viewing post in Lighthouse - The Storm Shepard comments
The hitbox on the ship is pretty generous you can click around it and it should select too.
You can click the ocean & press TAB followed by space to force select it again.
The post jam patch will have a proper way of unstucking boats & will try adding ways to prevent it from happening in the first place :)