Which ais aerial for pushpit?

[BlueChip]

I fitted one of those stubby emergency VHF antenna aerials on a 12" stainless pole on my pushpit to use as a dedicated ais antenna.
I was less than impressed with the ais performance when crossing Lyme Bay last week and on a couple of occasions ships got to within 4 miles of us before my ais picked them up, at other times I could see ships at 10 miles, so it seems the aerial may have some directional sensitivity.
The ais is working fine because if I change to my mast head aerial I see ships at about 15 miles

Does anyone have any experience of a regular masthead whip aerial mounted on the pushpit? Is this likely to give better performance?

 

[Playtime]

Does anyone have any experience of a regular masthead whip aerial mounted on the pushpit? Is this likely to give better performance?

I've just fitted a(nother) standard whip antenna (VTronix) for the AIS on a T pole at the pushpit. (Some miserable b-----d wiped out the previous one while the boat was parked in the marina, and never owned up.)

The antenna base is about 6 feet above the water and receives data from ships at least 12 miles away - far enough for all practical purposes.

Sat in the marina in Gosport I can see ships all round, even though most are not directly line of sight i.e. buildings and stuff in the way.

 

[Salty John]

Range in nm is about 1.4 x the root of the combined height in feet of the receive and send aerials; because ships carry their aerials high up it isn't as necessary for an AIS aerial on a yacht to be mounted as high as would be recommended for radio communication between yachts.
A rail mounted aerial at 6' receiving a signal from a ships aerial at 50' would have a range of around 12 or 13 miles. Fine for AIS use.

You still need a decent quality antenna, of course.

 

[CET1]

Just designed and made slim jim antenna out of some old copper wire and 19mm plastic conduit. Started it up last weekend picked up Sneafel on the IOM and ship in Workington all from Whitehaven. Only cost a few quid so will see how it goes this season.

 

[SJF]

I purchased a Pacific Seamaster 1m antenna (http://www.yachtbits.com/pacific_aerials/_seamaster_10mtr_whip_antenna_sv10f.php) with a view to mounting it on the pushpit for AIS reception/emergency vhf antenna use. I ran out of time during the install and decided to temporarily tuck the antenna in an upright position under the chart table.

A season on and I have no plans to move it as it performs perfectly well where it is and I can move it outside easily should I ever need to connect it to my vhf in an emergency.