Pilots, for years, have been filing flight plans with the FAA prior to setting off on a trip. Although the U. S. Coast Guard does not require one, it's a good idea to prepare a float plan and give it to a responsible person before getting underway. This plan should outline your boating itinerary including your time of departure and arrival and a time to contact authorities if you don’t arrive at the time described. It should also give information as to the description of your boat, the number of passengers aboard and instructions on what to do if you are overdue. Float plans are a "rescue tool" used by authorities in the event of an accident.
Here is a generic float plan that can be copied and edited for your own needs.
Please remember to communicate your float plan with a responsible person such as a family member or a friend. A float plan can be filed in the form of a formal written document, emails, text messages, phone conversations or other forms of communication.