The act does not prohibit such transport (it can't) - it applies a fine to be paid for any passenger which is transported from one US port to another, somewhere to the tune of $750. If an emergency requires a passenger to debark in US port, he/she is responsible for this fine (which is paid to cruise line, in turn paying to feds). I wonder if similar could apply to B2B.
It is a violation for a cruise ship to transport a passenger between different US ports without a stop in a distant foreign port.
From the PVSA (bolding mine):
Coastwise transportation of passengers—19 CFR § 4.80a
There are three common transportation
violations, set forth below, that can occur when a non-coastwise-qualified vessel transports passengers between U.S. coastwise ports.
First, a non-coastwise-qualified vessel transports a passenger directly between U.S. coastwise ports. (19 CFR § 4.80a(b)(1)).
For example, a violative coastwise transportation occurs when a passenger embarks in San Francisco and is carried to Seattle, where he/she disembarks.
The fine is assessed against the cruise line. Typically, the cost is then charged to the passenger's onboard account (so that the passenger "pays" the fine). And, if the cruise line continues to allow such violations, they can be banned from the ports involved. No cruise line will knowingly violate the law in this manner.
This fine is also assessed against a passenger that dies while on the cruise and the body taken from the ship in a different US port than originally embarked in. In that case, the fine can be challenged, and will, usually, be dismissed.
There's no such provision to allow any number of people to willingly violate the law and "just pay the fine".
BTW, the fine is now $778 for each passenger that violates the PVSA (I got that from the
https://help.cbp.gov/app/answers/detail/a_id/23/~/the-jones-act-&-the-passenger-vessel-services-act)
