Had one for an offshore sailboat race years ago, but never used it.
Damn. If you don't use them, then who does?
I know of quite a few use cases, but they are always "emergency only". Ocean races, arctic crossings, etc. There was one in one of the villages (Manang) on the Annapurna Trail, but they only used it to call in the rescue plane ($15k for the flight, the call was complimentary)