What is the difference between a fully loaded oil tanker floating and an empty oil tanker floating?
The main difference is weight of course. When fully loaded, the
ships airdraft is considerably reduced, as you can definitely see
the ship is more 'in the water', or more immersed.
When not loaded, or 'In ballast', the ship has several ballast
tanks which are filled up with sea water in order to weigh the ship
down a little, so as for it to not capsize with strong winds/rogue
waves. And a ship's hull/bulbous bow, etc.. are designed to
operate/navigate within a certain Loadline, hence the need to keep
the ship immersed within certain parameters.