HF is not the same as SSB
Single sideband (SSB)is a modified type of amplitude modulation (AM). HF (short for high frequency) is a reference to a range of frequencies - usually 3 to 30 Mhz. "Radio" can mean either a receiver or a transceiver. It is not precisely meaningful to call a radio an "ssb radio". There are AM or AM/FM broadcast radios, short wave radios, VHF radios, CB radios, ham radios, marine radios, FRS radios, cell phones, etc. None of those descriptions is really precise in that they refer to either modes of modulation, frequencies, functionality, or the type of radio service. Some have transmitter capability and some may not.From the context of this forum, I surmise that you mean a marine HF SSB transceiver.Licensing will depend to some extent on where the boat is registered. Use may be regulated by where the boat is located at the time. In the US, the FCC licenses most radio communications. If your boat is a US boat, I would recommend that you follow the FCC rules. The FCC can fine you even in foreign waters if you break the rules. They will mail you a notice of violation and you will need to respond.A marine HF SSB radio is licensed to the vessel so do not use it to transmit from anywhere except the vessel. IE: do not take it home and transmit to someone. You can take it home and listen though or get weather faxes, etc. You can legally receive marine band transmissions using a short wave receiver or the receiver part of a transceiver - no license needed. A marine SSB radio will often be useful for getting weather reports or faxes. That would not technically require a license. There are dedicated fax receivers and there are systems which use combinations of other equipment.Theoretically and historically, you do not need a license to receive anything. You are however generally legally prohibited from disclosing what you hear to a third party. It is complicated and archaic law. It is rarely enforced especially if you are a liberal democrat senator revealing conversations of a bunch of evil republicans to the NY Times for them to publish. Do not count on politics like that to protect you though.You need two licenses for commercial marine service which come from the same agency. One is for the operator and one is for the boats equipment. For using the ham radio service, you will need another completely different operators license. For you to use all of the possible common HF services, that means that you need three licenses.Marine radio transmissions are regulated by the FCC as a "commercial" service. Thus the licensing is for keeping the frequencies for that purpose only. No one else can legally use them or interfere with those who are licensed to use them.The FCC licenses manufacturers who make marine transmitters so that they are appropriately suited for marine use - IE: stable and do not cause interference to others, etc. The boat is licensed as a station capable of transmitting on marine frequencies and must meet these FCC standards.There are other "transmitters" which are also licensed by the FCC such as radars and EPIRBs. An EPIRB is also supposed to be registered with NOAA but there is no license that I know about with them. That may change.If there is any transmitter aboard your boat, it can be an issue with the FCC and other government agencies like the Coast Guard or local law enforcement as to whether you need a station license to have it aboard. Sometimes they will require it and sometimes not especially in foreign waters.The operator of a marine radio is expected to have a license to ensure that he knows the applicable laws for using it. A person not licensed may operate a marine radio only under the supervision of someone who is licensed.Further complicating the subject are ham radios which often are capable of receiving marine frequencies. Most of them can be modified to transmit on those marine frequencies as well. A modified ham transmitter is not likely to be type accepted by the FCC. Some (very few) transceivers are type accepted for marine use and are also useable on ham bands.It is not legal to transmit on marine frequencies with a transmitter (such as a modified ham radio) which is not "type accepted" by the FCC. Many people have done it though without any consequences. Others have been fined severely. You could be jailed if they wanted to prosecute for not having either an operator license or a station (boat) license.There are some marine radios which will transmit on ham frequencies too. You must have a ham license for that purpose but the FCC does not license ham radios as such. No ham license is technically required if you do not transmit on ham frequencies.Foreign governments will often want you to have all of the applicable licenses (be they marine operator, vessel station, or ham) and they may assess "fees" when you clear customs. I have heard that they will, upon occasion, confiscate unlicensed radios.To further add to the confusion on these issues is that you may transmit on any frequency or service with or without a license in a serious emergency. You may be expected to prove the emergency.Then there is the NTIA - oh well, never mind that.