AIS or Radio antenna at top of mast?

[jamie N]

If you put an AIS txr antenna that high, be sure to have/install a Class B SOTDMA ais transmitter, with a CSTDMA type it will receive carriers from all over the place and it might just wait ages until it finds a free spot to send your data.

Learn something every day dept.! I believe that the M10 is a CSTDMA Class B, as it is briefly mentioned, and the other one isn't in the manual. I think that's probably more of a worry in the Solent than around The Minch though, so I'll ignore it!
I bought the M10 5-6 years ago, and changing it out or upgrading isn't a possibility, er, my wife tells me.

 

[dom]

Learn something every day dept.! I believe that the M10 is a CSTDMA Class B, as it is briefly mentioned, and the other one isn't in the manual. I think that's probably more of a worry in the Solent than around The Minch though, so I'll ignore it!
I bought the M10 5-6 years ago, and changing it out or upgrading isn't a possibility, er, my wife tells me.

Okay, now for the important bit.; what's the boat as she sounds quite exotic !

 

[ip485]

Splitter - works great for me, not had any issues.

 

[jamie N]

She's an East German Folkboat, seen here in Cromarty Firth.

 

[dom]

Wow, just wow !! The boat, the setting, the hull, even the covers match perfectly

....had a feeling she might be a bit special!

 

[jamie N]

Mine's the 'tub' just behind the wooden one in front.....!
Rules 1 to 10: Enjoy Varnishing.....

 

[ip485]

Very pretty

 

[TernVI]

With suggestions that 75ft of rg58 coax will only transmit around 7.5w from a 25w set due to cable loss I would not be wanting anything else connected along the cable.
I get 1 mile ais reception without an antenna.
Can get 15 miles with antenna mounted on pushpit.
Ais wavelength is 1.85m, vhf is 1.88 so a proper ais antenna is shorter therefore why spend a small fortune on a splitter only to not use the correct length of antenna by using the vhf one ?

The tuning of the antenna won't matter much. The tuning you actually get when you mount it on some rigging instead of in a lab will change things anyway.
Antenna height will influence path loss much more than the equivalent cable loss. You might lose a few dB in a long cable, better than losing 10s of dB by dropping below the horizon.
I found raising the AIS by a few metres made a significant improvement in reception in circumstances like around the bend in Lymington River or inside Poole entrance or in the Medina. It's nice to know where the ferries are!
It's also handy to be able to show people how the AIS works while you're still in the marina and interesting to see what's going on.
I also don't like pushpit mounted aerials on the grounds I've seen a lot of broken ones, they are much safer away from crew and mooring lines etc.
So mounting on a pole is a bit of a compromise but works for us.

 

[pyrojames]

I have the VHF at the mast head and AIS on the port lower, about 2 feet from the mast. The Echmax is just above the upper spreaders of the front of the mast. However the mast is timber, not alloy.

As sea it has always been the Echomax that triggers first.