Good amateur practice and strict rule compliance have always characterized the operations of the vast majority of US amateurs operating within the US and in international waters. The FCC has even commended the amateur community for its self-policing abilities and for adherence not only to the rules, but also to unwritten ethics dictating high standards of conduct.
From time to time, problems do crop up, and these usually stem from misinterpretations of the rules or from myths surrounding the so-called "gray areas" in the rules. Nowhere is this more true than in the case of amateur maritime mobile operation in and around foreign ports. Even hams with good intentions often have trouble in determining just what they are supposed to do when in international waters, e.g., the high seas.
On the darker side, while certainly not characteristic of most amateur maritime operators, unscrupulous yachters have been known to operate on the ham frequencies without a license. They often are of the mistaken opinion that, because they are on the high seas, the rules somehow don't apply to them. These unlicensed operators often do not install maritime mobile emergency communications gear, relying instead on a ham transceiver for all communication. This disregard of the rules and of domestic law can, among other things, complicate US and foreign efforts to reach third party traffic and other such agreements.
Article 1 of the Geneva Convention of 1958 on the "high seas" states: "The term 'high seas' means all parts of the sea that are not included in the territorial sea or in the internal waters of a state." Article 2 states: "The high seas being open to all nations, no state may validly purport to subject any part of them to its sovereignty." The sovereignty of a state extends to the airspace above the territorial sea as well as to the sea floor and the subsoil beneath it.
Several things will come into play here.
First, in many cases, you will first need the permission of the cruise ship company itself to even have an AMateur Radio transmitter in your possession while on board (whether in use or not). So your first step is to make sure you have written authorization to have your radio with you.
Next, besides the company itself you will need to have permission of the ship's captain in order to use the radio. Do not assume you can simply throw up a vertical outside of your stateroom and operate!
Once you have authorization top operate ship board, you still have to worry about reciprocal operating privileges with the country where your ship is, including territorial waters,
When an FCC licensed amateur is operating an amateur rig aboard a US-registered vessel in international waters, he or she must follow Part 97 of the FCC rules, particularly Section 97.11. US and Canadian licensees need no special permit or authorization other than their own FCC or DOC license as long as Section 97.11 is followed and they stay within the US and International waters.
If the ship is of foreign registry, you must obtain a reciprocal operating authorization from the country of registry in addition to being in compliance with Section 97.11. When amateurs enter the territorial waters of a country, they fall under their communications jurisdiction. This means that they must obtain the required reciprocal operating authorization. There are three such authorizations: CEPT which applies to most European countries and certain overseas territories; IARP which applies to certain countries in the America's; Reciprocal Permit which is available from most countries, but application must be made to the country and a fee paid.
You must abide by the rules of the bilateral or multilateral reciprocal operating authority or the reciprocal permit as mentioned above.
While many countries have similar rules to those of the US, the frequencies, power limitations, identification requirements and other regulations can vary widely. We in the US often assume that Amateur Radio operators in other countries have been allocated the same frequencies that we have. This is simply not the case. Each of the three International Telecommunication Union (ITU) "Regions" have their own allocation for the various services, and they do not necessarily conform to our frequencies in the US, which is in Region 2. Amateurs operating maritime mobile must not exceed the frequency limitations for each ITU Region as authorized in the international Radio Regulations.
When operating from the US, its territories or international waters, you must meet all three requirements in Section 97.11 of FCC rules: "(a) The installation and operation of the amateur station on a ship or aircraft must be approved by the master of the ship or pilot in command of the aircraft; (b) The station must be separate from and independent of all other radio apparatus installed on the ship or aircraft, except a common antenna may be shared with a voluntary ship radio installation. The station's transmissions must not cause interference to any other apparatus installed on the ship or aircraft; (c) The station must not constitute a hazard to the safety of life or property. For a station aboard an aircraft, the apparatus shall not be operated while the aircraft is operating under Instrument Flight Rules, as defined by the FAA, unless the station has been found to comply with all applicable FAA rules." When you're in International waters, you operate under the auspices of your FCC license, but you must be mindful of the frequencies assigned to other ITU Regions. The world is divided into three "pieces of the pie." You are bound by the privileges assigned to the ITU Region from which you're operating and by the privileges as outlined by your FCC license. It's a good idea to follow your call sign with the words "maritime mobile" or "aeronautical mobile" followed by the proper ITU Region number.
If your station is operated in Europe, Africa or the adjoining waters, you're in Region 1. North and South America and the adjoining waters make up Region 2. The "rest of the world" is comprised of the countries of Southern Asia (excluding the countries of the Arabian Peninsula) as well as the islands of the Pacific and Indian Oceans.
In cases where FCC rules apply, you may pass third party traffic and make phone patches to countries with which the US holds third party traffic agreements. You may not pass traffic with countries which have not signed a third party traffic agreement with the US and there are never any exceptions to these rules. Even thoughtless violation can cost amateurs the good reputation we have earned over the years.
The territorial limits extend to whatever that particular country says they do. The US claims 3 nautical miles. Most Caribbean island nations claim 3-12 miles although there are exceptions. The territorial limits of certain Caribbean nations and other island nations whose area consists of many small islands often overlap creating a larger territorial area than one would assume.