AIS aerial for pushpit mounting

I'm fitting a dedicated one at the moment for a transponder.

I'm gonna try mounting it inside cockpit moulding which I can access easily and doesn't require any holes to be cut.

If it works there and gives 10nm range then that is where it will stay as it will save having yet one more hole in the boat and another thing on the pushpit to get snagged on children / sheets / etc....

Will let you know how I get on.
 
"I'm gonna try mounting it inside cockpit moulding which I can access easily and doesn't require any holes to be cut"

If it is for a transponder is it ok for this to be so close to crew ?
 
Newsailer said:
There is something definatly not right about that statement. You have an AIS aerial monted inside your lazarette , which must put it about a metre above the water, and you reckon you still get targets over 20 nm away!

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.
Click to expand...

Well, science is a funny thing isn't it.
Our aerial under the coaming is about 1.8m above the water.
I didn't say we saw every ship. Who knows? All I know is that when crossing shipping lanes we always see the big targets at 20nm.

As far as the smaller stuff, if it's only 10 miles thats way more than enough for me. I use AIS for collision avoidance and I don't even start avoiding outside a mile.
 
Last edited:
Tex said:
"I'm gonna try mounting it inside cockpit moulding which I can access easily and doesn't require any holes to be cut"

If it is for a transponder is it ok for this to be so close to crew ?
Click to expand...

Interesting question. If it was on the pushpit it would actually be closer to crew when sailing. I can't recall what the tx power is, but it isn't huge, and it is VHF frequencies, which many use on a handheld close to their head.

That's my reckoning anyway.
 
You must log in or register to reply here.

Share this page

Top