TV Antenna For AIS ?

[philbyrd]

I have a R25 in production and am planning the first round of upgrades.

Looking into a AIS transponder as my home port is a busy commercial harbor.

It occurred to me the stock majestic TV antenna can double for AIS with a simple switch. Digital TV uses both UHF and VHF. Can’t imagine when I would need both at the same time except perhaps an anchor watch use. Save cost on a splitter for the existing VHF and avoid the conflict when both are in use.

Anyone done this or have thoughts?


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[SJI Sailor]

Don't know about the TV antenna, but I have two notes. First, many AIS have the splitter built in so there might be no cost. (Our Garmin 800 does, for example.)

Second, it might depend where you will locate it and which antenna is available there. In our case, we put the unit inside the helm cabinet, so it was very simple to move the antenna plug from the radio to the AIS, and then attach the output from the splitter back to the radio. They were within a few inches of one another. I don't know the details for an R25 though.

BTW, we are very happy to have AIS broadcast. Besides the safety aspect, it lets us and friends monitor the boat. It was handy recently, for example, when I saw that the boatyard doing bottom paint had moved her into the water, so I called and found out she was ready to go.

 

[adueser]

Make sure you get the right class because of the speed of your boat.

https://www.navcen.uscg.gov/pdf/AIS_Com ... _Class.pdf

 

[philbyrd]

Thanks both, I thought A vs B related to size and commercial use. The USCG chart is not intuitive. USCG also states that "[v]oluntary AIS users may avail themselves of either a AIS Class A or B device, but, such device must be FCC certified for its use in the United States." Is there a issue at speed with a Class B device such as the Vesper 8000 that is my front runner?

 

[FlyMeAway]

If you’re having the boat built I’d see about doing away with the stock VHF and upgrading to a Vesper Cortex all in one unit.

 

[adueser]

As you can see in the pdf I sent the link to on page two. There it says that with the ‘regular’ class B at 24 kn a signal is sent every 30 seconds during which you travel 370 m which is more than 1000 ft.


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[FlyMeAway]

As you can see in the pdf I sent the link to on page two. There it says that with the ‘regular’ class B at 24 kn a signal is sent every 30 seconds during which you travel 370 m which is more than 1000 ft.


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Yes. This is why you want a SOTDMA Class B, like the Vesper Cortex.

If I were building a new boat, that's the only AIS system I would get. When you consider that it is AIS, antenna splitter, boat monitoring, NMEA2k -> Wifi bridge, it is a bargain. When you realize you can include VHF (and maybe omit from your existing build), it's basically a steal...

 

[SassyRed]

Since you want to transmit as well as receive, the below article may help.

https://www.milltechmarine.com/How-to-C ... _b_34.html

I recommend Milltech and Doug Miller as very knowledgeable AIS resources to help you review your device choice.
As others have said, if you want to reuse an antenna, reuse your VHF radio antenna via a splitter, whether built into the AIS unit or part of you VHF radio. And a tuned AIS antenna for a few hundred dollars is the best bet.

 

[philbyrd]

Thanks all, yes I plan on speaking with Milltech.

 

[philbyrd]

Just to close this out, spoke with Milltech and the TV antenna will not support AIS. Dedicated antenna or splitter on the VHS needed. Hopefully I get points for creativity that outweigh wasting everyone's time!