Leastways thats the difference between a marine band SSB and one that also operates on the ham frequencies. Cut the right wire and your in business.
Marine band you can operate with a ship's station license (which also inludes VHF, and others plus a permanent station operators permit which is just fill out the form and pay a small fee.
Least that's the way it was some years ago.
I through this in so the true technoids could cover all the bases with up to date informatio.
Thanks to them and you for bringing the subject up.
Michael S