Are you planning to sail to Cuba with a planned departure from within U.S. territorial waters?
If so, then you need to file form CG-3300.
Recreational boaters on U.S. flagged vessels that are less than 100 m (< 328-feet) must have a
Coast Guard permit to depart from within U.S. territorial seas.
An applicant must submit information on form CG – 3300 to the Coast Guard seventh district
before a permit can be issued authorizing a departure to Cuba.
NOTE: At present, U.S. flagged boats are only granted a 14-day stay in Cuba.
CG-3300 (application form and instructions).
The first link will take you to the form and the second link to the instructions for filling out the form.
Application for permit to enter Cuban Territorial Seas (Form CG-3300)
http://www.uscg.mil/hq/cg5/cg531/CG3300.pdf
Instructions for filling in form CG-3300
http://www.uscg.mil/hq/cg6/cg611/COI/omb/1625-0106.pdf
