HF Radio

Primary long-range radio system for fishing vessels

Frequency range 3 to 30 MHz
Long range from its ability to bounce against atmosphere
Specific range depends on frequency and current atmospheric conditions

Transceiver may also handle MF frequency range

Wide range of antenna designs

Shore antennas can be tens of meters long
Various technique allow "folded" antennas
Shipboard installations may run along stays or upper masts
Especially if you try to use the antenna for MF as well, there can be inefficiencies, but additional coupling equipment can improve the situation. Consult a qualified FCC-licensed installer for antenna layout.

Can use

Digital Selective Calling 
which uses Maritime Mobile Service Identity (MMSI) as “phone number”

Generally fixed mount