I think you or your brother own the boat. Be careful of the tax implications. If it’s a US documented boat and you go into Puerto Rican waters a duty of 1.5% is probably due if not already paid. That is the rule. From a practical standpoint I don’t think there is a attempt at enforcement as you are supposed to self disclose. Here is the best explanation I could find. I confirmed it with a call to customs as I looked at putting my boat in the USVI.

It is not uncommon for US Customs to fail to identify US-flagged boats that should pay duty upon entry into the US. This typically happens to USCG-flagged boats that were made outside the US and the members of NAFTA/etc, such as many French Beneteaus or South African Leopards that work for 5 years in the BVI charter fleets and are then taken to the US by the owners (as opposed to a delivery skipper bring ing in a new boat fromFrance that has not even been registered, hence clearly seen as subject to duty).

Note that when you got the the LBO card you may have said things(like providing a US address in the form) that may make it difficult to argue that you are not a US resident.

Their failure to tell you that you need to pay duty may not be a good defense for you when they ask you how come you went in without paying duty. I suggest you ask a customs broker who knows about boat imports, of which there are not many. AFAIK you can only find them in places (California, Washington state and Florida) where every once in a while Customs catches some duty evaders.

I believe that in most of those cases the owners mistakenly believe that the US flag (which confuses the Customs guy) means they do not need to pay duty. AFAIK if you want a legal way to avoid triggering duty when you enter the US with a French cruising boat to cruise US waters you need to have foreign flag and non(US) resident owner and apply for either a cruising license or a normal clear-in form (with the attending hassle of reporting movements, etc, restrictions on trash disposal, etc)

Don´t get confused with the "duty on sale" situation for foreign-flagged foreign-made boats on cruising licenses. Sale (or offer for sale) will trigger duty on those boats (see parts b-c-d of 4.94, which are for foreign-flagged boats) . IMHO in your case you should worry about not having filed an import declaration (and then paid duty) when you went in the first time.

Also don´t get confused about Puerto Rico. As far as duty is concerned Puerto Rico is one more state. If Customs in PR can catch you for duty the Customs in Florida also can. Only difference I know is that those Boricua federal employees seem to know their rules better than their brothers in Florida. USVI is another story because they are a special customs territory (loosely defined).

I was told once that there is no statute of limitations for this sort of thing if you did not file an import declaration (as opposed to filing an incorrect one). Your mileage may vary.