AIS installations

[mm5aho]

In considering installing an AIS receiver, I notice there seem two possibilities with antennae. Maybe three?

1. Fit a seperate antenna in a location such that the VHF transceiver's signal doesn't ruin the AIS by overloading it.
2. Fit a splitter and connect both to the same one antenna. A splitter would of course be a cost on top of the receiver.
3. Get a receiver that has a built in splitter enabling both to be connected to the same antenna. (such as the Icom MXA5000)

As my marine VHF antenna is at mast head, it seems to me that having the AIS ant there too isa good idea (line of sight, height, range etc). But there doesn't seem space to fit two, not without them interfering.
One idea is fit the AIS antenna on the spreaders?
I already have another VHF antenna on the pushpit, but this seems too low for good AIS range.

Any experience with this? Advice? No rush, as this is probably a next winter job, but its during the summer that I think of these things.

[wully]

I bought a Standard Horizon VHF with built in AIS receiver which after a lot of trauma (due to my incompetence) managed to get it talking to my chart plotter.
Result?

Continuous spurious ' dangerous AIS target' alarms from boats on moorings and more usually, in marinas.

Unless the viz is sh1 t, I turn the bloody thing off...

[cpedw]

I speak with no personal experience of AIS but I would expect that low mounting would be a benefit. That would give a line of sight range of several miles, which I think should be plenty, and will filter out targets further away that could overload the system with irrelevant messages.

On second thoughts that's not going to be a problem round the Hebrides is it, and it doesn't eliminate spurious messages from nearby moored boats.

Derek

[Nick]

.
We have our AIS aerial on the pushpit and it's fine (not that we use it a lot . . . )

Line of sight is several miles to the broadcasting vessel's antenna, which is more than enough.

[mm5aho]

I have an existing ham bands VHF antenna on the pushpit and its surprising what I can do with that, so it might be as well having an AIS one there too.
I'd initially thought of getting max range, but maybe thats a wrong assumption (overloaded with signals).

I noted last trip out, that I was hearing, from the same place, Coastguards from Belfast, Stornoway, Liverpool and Hollyhead. Imagine how many AIS signals emanate from that area?

[Tex]

I have AIS aerial on pushpit and regularly pick up contacts at 25M. Great bit of kit and I would like to upgrade to transmitter but costs still prohibitive, for me anyway.

[DaveS]

I have two VHF antennae at the masthead: a conventional dipole (combined with a windex) and a wee "rubber duck" helical type. They don't seem to interfere with each other significantly. The cabling is arranged so that either can be connected to the VHF or the AIS giving some flexibility / redundancy, but usually the dipole is used for the VHF and the rubber duck for AIS. Range is fine with targets appearing at 16 miles or more.