Any passage that takes you out of sight of land or more than 12 miles offshore and lasts for more than 12 hours. If you have landed here looking for a definition of offshore sailing for insurance purposes do not take this or any other definition for granted – make sure you read our notes on buying sailing holiday insurance. offshore sailing means the crew go into watches, usually two watches which change every four to six hours. As one of the crew you will be allocated to one of the watches. Any time Trinovante is out for more than a day sail there will be a watch system. With SchoonerSail, offshore voyages can be anything from 60 to 800 miles lasting from 24 hours to a week.