From personal experience with a BVI boat in Florida
and the Bahamas, I have found the following:
Providing you are a US citizen you can easily obtain a 1 year cruising certificate for your foreign registered boat at customs/immigrations when you enter the US. A USCG offficer told the forum that the rules were stricter in South Florida but no one at my sailing club in Miami
knew of these rules, nor were they applied any of the 3 times I entered. My English
friends who are about to sail into US waters and stay for an extended period had to obtain visas from the US Consulate in Trinidad.
After 1 year you must leave for 2 weeks before reentry for another year.
permits in Florida but theoretically, I am told, you are supposed to get a 3 month cruising permit
and after 3 months they can charge you 6% sales tax but having kept non-Florida registerd boats in Florida for a total of 4 years I have never seen those rules enforced...but maybe I was fortunate. In Florida, the new anchoring
rules allow you to anchor
anywhere but in a designated mooring field, but there is no evidence, as of yet, that the local police have read the rules.
In the Bahamas you need a $300 cruising certificate which is good for 3 months, this I have heard is enforced.
Good luck Phil