The language “Not For Sale In US Waters To A US Resident” must legally be added to all listings for non-US Registered boats that are in US Waters under a cruising permit and placed up for sale by the owner. Due to the current owner of the boat having not paid the US Import Duty on the boat, a sale cannot legally occur on the boat to a US Resident while she is in US Waters, and you cannot legally advertise the boat without making prominently clear that the boat is “Not For Sale In US Waters To A US Resident”.
But this does not mean that a US Citizen cannot purchase the boat, there are few ways around the problem.
There are a couple of ways a sale can occur with the Catamaran you are looking at, as a US Citizen and the Catamaran is physically in the US.
The first and preferred way would be for the seller of the boat to purchase a US Customs Entry Bond and pay the US Import Duty due on the boat. Exact rates of the US Import Duty would depend on where the boat was built and can range from .02% to 1.8% of the value of the boat.
The second way would be an “Offshore Closing” or a closing that occurs in the Bahamas or somewhere else outside of US Territory that is at least 12 nautical miles off the coast. An “Offshore Closing” transaction does complicate matters slightly as potential buyers for boats that have not been US Duty paid cannot board or view the boat while she is US Waters, so the transaction details must follow a strict protocol that abides by the laws of the United States.
Many foreign flagged boats decide to delay paying the US duty on the boat while she is being marketed for sale in US Waters as to potentially sell the boat to another non-US citizen who CAN purchase the boat in US Waters without the owner having to pay the US duty prior to the sale.