blow off course

== English == === Etymology === In the Age of Sail, ships were occasionally diverted by unexpected winds, getting lost possibly to shipwreck or to a new destination. See blown off course on Wikipedia.Wikipedia === Verb === blow off course (third-person singular simple present blows off course, present participle blowing off course, simple past blew off course, past participle blown off course) (transitive, figuratively, often in the passive) To affect negatively, often in an unexpected manner; to derail.