I,m about to step the mast on my boat and would like to know the pros & cons of attaching the antenna to the boat or top of the mast? Thanks Walt
To answer your question, Walt...
Attaching the antenna to the top of the mast: Pro (there's only one, but it's a biggie): Potentially much
greater range. Two boats with an antenna height of 6 feet (approx. 2m) have a line-of-sight (LOS) distance to one another of 6 nm. If just one boat gets its antenna up to 40 feet (12m), their LOS distance goes up to 10nm. If both
boats have their antennas at 40 feet: Their LOS distance goes up to nearly 16nm. Marine VHF radio is all about LOS, which means height. Cons: It's much harder to install and service. If you're a racer, for whom such things matter, you're adding significant weight aloft. (Not so much the antenna, but the coax.) Your radio will be more susceptible to destruction by lightning. If you're demasted: There goes your antenna.
Now take the pro and cons for the masthead installation and reverse 'em for mounting down below and you'll have the pros and cons for that location
FWIW: Our antenna is mounted on the transom. I plan to add an antenna to the masthead some day. I'll leave the antenna on the transom as a backup. I'll also upgrade the radio to one with DSC and a remote access mic. Between the impaired range and the radio being down below, it's not very useful to us right now.