Another thing that can affect a radio signal is the proximity of another antenna. When we added a second antenna for our flying bridge radio to replace the selector switch that had been there when we got the boat, the proprietor of the electronics shop we used cautioned us to make sure the new antenna was NOT a specific distance from the other VHF antenna or a multiple of that distance. It's been a long time since we did this so I don't remember the basic distance but seventeen inches comes to mind.
The reason given had to do with the wavelength and the partial signal blocking an antenna at these distances from the transmitting antenna could cause.
Of course if this is a new problem for the OP or for this particular boat, then antenna position would not be a factor since everything was working fine before.
The reason given had to do with the wavelength and the partial signal blocking an antenna at these distances from the transmitting antenna could cause.
Of course if this is a new problem for the OP or for this particular boat, then antenna position would not be a factor since everything was working fine before.