To copy a vessel; open a vessel drawer and click the triple dot icon(secondary action menu) in the top right and then select Copy Vessel.
Clicking Copy Vessel will open a Copy Vessel modal where you are prompted to enter the vessel-copy's name.
When you click Create, a drawer of the copied vessel will be opened. The vessel will have all of its data copied over from the original vessel except the name of the vessel will be set to the Vessel Name you entered in the Copy Vessel Modal.
The internal data of the copied vessel will be given default values on fields like company, business unit, vessel code and vessel. The vessel code will be set to the vessel's key-number value, which is unique for the vessel.