Thanks Capt. Ted for those informative remarks !

Matty
Virtually trying out if the ship functions as per described building contract between builder and owners. Measurments are taken on machinery, for example max rpm on egnines/temps during that/what speed vessel reaches.Maneuvering ability, truning circle/stoppage time with full ahead to full astern. All elektronic components
on the bridge as well in the engine room. Vibration measurments at certain aeas, noice levels at different speeds and if those are withhin acceptable limits.
etcetc,,, virtuallt after the sea trials the owner takes the vessel over or not, depends how it works all over. If all ok,,or things can be fixed rather easy the flag change takes place and usually the flag of the building yard is lowered and the owners flag raised. The flag under which the ship sails later is usually the same under both.

What does sea-trials actually mean ? What do they involve ?