Aerial combinations for car VHF radios on board?

I would never use a splitter. Aerials are cheap enough or easy enough to make yourself to allow for one for each system. I would be concerned about AIS and VHF com on one mast top. Just not enough spacing as com could damge AIS reciver with 25 watts possibly getting into the other aerial. far better AIS on the stern rail also useable as emergency com antenna.

1. The price of an individual antenna for each may be affordable enough, but there's also the cost/labour involved of running 2 or 3 cables up the mast (19.6m in our case).
2. AIS (like VHF) is effectively LOS - so keeping the antenna on the stern rail reduces it's range/effectiveness.

Boats/owners/sailing are all different, but I think that in our situation a 3-way antenna splitter AIS/VHF/FM made perfect sense.
 
With a splitter and when listening to the stereo do you get a momentary loss of reception when the AIS or VHF transmit?

Can't say I noticed that.
Certainly not when the AIS transponder is on.
When I use the VHF, I tend to turn the radio down/off anyway - no-one needs/appreciates radio noise in the background of a VHF transmission.
 
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