A sea trial is the marine equivalent of a test drive, crucial for assessing a vessel's performance before it is fully commissioned or sold. A sea trial or trial trip is the testing phase of a watercraft (including boats, ships, and submarines).It is also referred to as a shakedown cruise. Sea trials are an important step within the boat buying process that allows you to take a boat for "test run. Read page 2 of the latest CBS Village Latine news, headlines, stories, photos, and video from CBS News. "Cash purchase" appraisals; Estate planning.