Sec. 80.311 Authority for distress transmission.

A mobile station in distress may use any means at its disposal to
attract attention, make known its position, and obtain help. A distress
call and message, however, must be transmitted only on the authority of
the master or person responsible for the mobile station. No person shall
knowingly transmit, or cause to be transmitted, any false or fraudulent
signal of distress or related communication.

Sec. 80.89 Unauthorized transmissions.
Stations must not:
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d) When using telephony, transmit signals or communications not
addressed to a particular station or stations. This provision does not
apply to the transmission of distress, alarm, urgency, or safety signals
or messages, or to test transmissions.
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(f) Transmit while on board vessels located on land unless
authorized under a public coast station license. -- snipped rest of f ---

Sec. 80.177 When operator license is not required.
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(5) A ship station operating in the VHF band on board a ship
voluntarily equipped with radio and sailing on a domestic voyage.

Sec. 80.115 Operational conditions for use of associated ship units.
(a) Associated ship units may be operated under a ship station
authorization. Use of an associated ship unit is restricted as follows;
(1) It must only be operated on the safety and calling frequency
156.800 MHz or on commercial or noncommercial VHF intership frequencies
appropriate to the class of ship station with which it is associated.
(2) Except for safety purposes, it must only be used to communicate
with the ship station with which it is associated or with associated
ship units of the same ship station. Such associated ship units may not
be used from shore.
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(b) State or local government vehicles used to tow vessels involved
in search and rescue operations are authorized to operate on maritime
mobile frequencies as associated ship units. Such operations must be in
accordance with paragraph (a) of this section, except that the
associated ship unit: May be operated from shore; may use Distress,
Safety and Calling, Intership Safety, Liaison, U.S. Coast Guard, or
Maritime Control VHF intership frequencies; and may have a transmitter
power of 25 watts.


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From what I read, if it's an emergency, no problem. This goes for all radio services. You can run into trouble if after you've been recognized and someone has taken your information, if you keep transmitting and interfering.

As for your scenario, I could not find an adequate notion of where the maritime service is located. It may be in another part of the FCC code. Martime Radio Service is defined in Part 80. There is no clear description of what "land" is. I expected something like "mean high tide" or something. I looked at this, for curiosity sake for myself, over 30 minutes.