Two most likely scenarios:
- bad antenna and/or coax.* This has the potential to make your signal directional - good radiation in some directions, poor in others.* Simplest way to test is to see if another boat gets similar signal quality as you turn the boat through 360 degrees.*
If you have 12 year old coax, that would be the first thing to replace.* In particular, any sort of crimping, kinking, or connector problems can give all sorts of trouble.* If you even think about replacing the antenna or radio, you*shouldUse a *replace the coax, too - so do it first; that may be all it is.* Use a good quality coax - RG142 or RG400, not RG58.** Use crimped connectors with the proper crimper.* Examples:
- transmitter off frequency.* Different receivers have different capabilities to capture an off-frequency signal, so the same transmission might be quite reasonable for one radio and almost undecipherable to another.* A decent radio shop should be able to do a quick bench test to verify transmit frequency and output power.
My suggestion would be to do the radio bench test and replace the coax.* If the radio tests out OK and you still have the problem, then replace the antenna.