There are set frequencies or "channels" that are allocated to the Marine SSB. If you have a manual for the radio or download from the net, it will most likely tell you what those channels are. They most likely will be programmed in the radio. You may listen to those channels without a license, but as Mytraveler said, you will need a boat and personal license to transmit on the radio, just money. The channels are very diverse in frequency which will require an antenna tuner if you are using a single "vertical" antenna. An auto tuner is best for someone not well versed in radios and may be part of your setup. Although not part of your question, HF radio is a must if you are doing any cruising outside the US/Canadian borders. I prefer the ham radio environment but also had a Marine SSB onboard and used it to check into marine "nets" where boats would check in from their various locations giving weather and other interesting data. You should be able to "google" Marine radio nets" and find the frequencies of ham nets and channel and times for the marine SSB nets and listen in. Most marine SSB radios will allow you to listen to the ham frequencies. It depends on how old/modern your radio is. Unlike FM VHF marine radios, the HF realm, depending on the frequency, may have long range, medium or short range or even no range depending on the atmospherics, time of day etc. There is too much that affects its communication capabilities to describe here. There's tons of literature describing the capabilities. I've used it to send email from Antarctica using Winlink on the ham SSB and hold daily conversations with buddies in Hawaii and Calif from there, from Caribbean and elsewhere around the world. You can listen to boats checking in from Tahiti from your boat in Wa. It will be worth it to get legal with the SSB HF radio if you already have it.