Lets look at a typical yacht radio system.
This particular system is from an actual yacht, which cruises the mediteranean.
ICOM VHF Marine IC-M330
VHF is a line of sight frequency band.
Therefore as the sea is flat, its useful.
Being line of sight means that its relatively short range.
This is because of the earths curvature.
VHF line of sight radio signals will only go so far.