^^ yes, except if he wants to get off the boat in some places I believe there is going to be visa requirements where there is none for an American - this is true for instance in Panama
just as an example:
STAMPED VISA: IF YOU ARE FROM ONE OF THE FOLLOWING COUNTRIES ... YOU WILL NEED A STAMPED VISA. IN ORDER TO APPLY FOR A STAMPED VISA, YOU WILL NEED TO SEND US ALL THE SAME PAPERWORK AS IS LISTED ABOVE FOR THE AUTHORIZED VISA.
Please be advised: for stamped visas, the approval process may take up to 30 business days, depending on the verification and completion of your documents. Do not finalize your travel arrangements until your visa has been granted.
NOTE: IF THE VISA IS GRANTED, YOU MUST COME PERSONALLY TO THE CONSUALTE TO GET THE VISA STAMPED ON YOUR PASSPORT
Central African Republic
Republic of China
Republic of the Congo