I thought about an AIS only aerial, but the one I fitted also doubles as an emergency aerial, should I be silly enough to lose the mast
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Thread: AIS aerial for pushpit mounting
21-02-12, 17:54 #11Apogee Sabre 27, Tollesbury
Apogee =The highest point in the development of something.
21-02-12, 18:16 #12
What I meant was that the ANT200 is more expensive (about £200) then a separate VHF aerial and AIS engine (about £150 together). We already have a DSC VHF and a plotter to connect the AIS into. Also as far as I know the ANT200 can't be used as an emergency aerial - but I'm not 100% sure on the last bit.
So on balance the modular solution seems best.
Last edited by Sinc; 21-02-12 at 18:16. Reason: Can't spell!
21-02-12, 19:19 #13Registered User
- Join Date
- Nov 2006
Our AIS aerial, like our GPS aerials, is fitted inside the boat, under the cockpit coaming (actually in the lazarette on our boat). Slightly reduced range I suppose, but it is in a warm, dry environment, can't be knocked about and we still pick up targets from over 20nm so who cares?
Last edited by Ex-SolentBoy; 21-02-12 at 19:30.I may be wrong, but I'm not confused.
21-02-12, 19:20 #14
Incidentally I fitted a dedicated AIS aerial from Salty John and am in the process of fitting it now this week.
21-02-12, 21:20 #15
22-02-12, 12:49 #16
The main difference is that the AIS antenna is not fitted to the top of a (possibly detached) mast.Nigel
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22-02-12, 14:29 #17
23-02-12, 11:31 #18
23-02-12, 11:56 #19Registered User
Location : 2
- Join Date
- Jan 2005
AIS, like VHF, works on line of sight. I have used various AIS products linked to varuis electronics with the aerials usually mounted 3 - 4 metres above the water. I rarely see any AIS targets over about 15 miles.
Your own VHF horizon for the AIS antenna is only about 2.5nm away. Obviously you can rely somewhat on the height of the aerial of the other vessel but to see one at 20nm you would need their aerial to be at about 60 metres, and I have not included in this the loss of signal caused by the airial being enclosed.
With a typical air draft of around 45m you simply should not be able to see most ships with your setup at 20nm. A small fishing boat shouldn't come into visibilty until they are about 6 miles away at best.
23-02-12, 12:44 #20
My experience with a pushpit mounted cheap VHF aerial as AIS receiver(which can also double as emergency VHF aerial) is that it is perfectly capable of receiving AIS transmissions fro 15+ miles away. The person who cannot see more than 2.5 miles really ought to check his connections and the integrity of his aerial.