Antenna dilemma

[steve yates]

I had two masthead antennae for years on my old boat. I never noticed any poor performance from either the VHF or the AIS. We generally saw larger vessels at 50-80nm distance, and occasionally hundreds of miles, which I presume was some sort of atmospheric effect at work.

Are ais ariels not tuned to a much tighter frequncy than vhf ones anyway? So unlikely to interfere across most of the band?
Edit: just read post 19, ignore me