AIS transponder + splitter combo

[mikefleetwood]

Last winter, I fitted Musketeer with an AIS receiver and a splitter. I now realise that without spending a great deal more I could have a transponder. I have found two models for just over £600, and would like to hear opinions on if they are any good. I'd especially like to hear from anyone with user experience.

I'm looking at the Comar T200B-S and the Em-trak B293, but open to other suggestions.

The B293 includes in-built GPS, but has a lower transmit power.

I hope to be able to use GPS NMEA output from my Garmin echo-map, and display AIS targets using the same device.

Many thanks.

 

[PaulRainbow]

Last winter, I fitted Musketeer with an AIS receiver and a splitter. I now realise that without spending a great deal more I could have a transponder. I have found two models for just over £600, and would like to hear opinions on if they are any good. I'd especially like to hear from anyone with user experience.

I'm looking at the Comar T200B-S and the Em-trak B293, but open to other suggestions.

The B293 includes in-built GPS, but has a lower transmit power.

The Em-trak is B923, not B293. Both models are 2W CSTDMA (class B). The Em-trak B953 is 5W transmit SOTDMA (Class B+)

The Comar is built by SRT, the parent company that makes Em-Trak. I would go for the Em-trak, (i am an Emtrak dealer)

I hope to be able to use GPS NMEA output from my Garmin echo-map, and display AIS targets using the same device.

Not sure what you mean here ?

 

[mikefleetwood]

The Em-trak is B923, not B293. Both models are 2W CSTDMA (class B). The Em-trak B953 is 5W transmit SOTDMA (Class B+)

The Comar is built by SRT, the parent company that makes Em-Trak. I would go for the Em-trak, (i am an Emtrak dealer)

Not sure what you mean here ?

Sorry typo in Em-trak part number!

I guess I was trying to say that because the echomap has a GPS output, I don't need an AIS transceiver with built-in GPS.

Thanks.

 

[PaulRainbow]

Sorry typo in Em-trak part number!

Thought so

I guess I was trying to say that because the echomap has a GPS output, I don't need an AIS transceiver with built-in GPS.

All AIS transceivers have built in GPS Mike, it's a requirement as part of the AIS standard. Some have an internal GPS antenna, some are external, but the actual GPS receiver has to be internal, you cannot send GPS data from an external source. You can, however, output GPS data from the AIS, to, say, a VHF etc.

 

[ithet]

If I was buying an AIS Transponder now I would really want to stretch to a SOTDMA unit.

 

[KompetentKrew]

If I was buying an AIS Transponder now I would really want to stretch to a SOTDMA unit.

Am I correct in recollecting that a standard B only transmits position every 7 minutes?

 

[PaulRainbow]

Am I correct in recollecting that a standard B only transmits position every 7 minutes?

No. Unless you are doing more than 14 knots, transmission times are the same between B and B+.

Comparison SOTDMA and CSTDMA	SOTDMA	CSTDMA
Transmit Power	5 Watts	2 Watts
Transmit refresh rate	5 seconds	30 seconds
Guaranteed Time Slot Allocation	Yes	No
Transmit Rate	5 seconds	30 seconds
Vessel at anchor/moored	3 mins	3 mins
SOG 0-2 knots	3 mins	3 mins
SOG 2-14 knots	30 seconds	30 seconds
SOG 2-14 knots and changing course	30 seconds	30 seconds
SOG 14-23 knots	15 seconds	30 seconds
SOG 14-23 knots and changing course	15 seconds	30 seconds
SOG > 23 knots	5 seconds	30 seconds
Other vessel information	6 minutes	6 minutes

Table courtesy of Aves Marine

 

[KompetentKrew]

Thank you, @PaulRainbow.

 

[mikefleetwood]

Thought so

All AIS transceivers have built in GPS Mike, it's a requirement as part of the AIS standard. Some have an internal GPS antenna, some are external, but the actual GPS receiver has to be internal, you cannot send GPS data from an external source. You can, however, output GPS data from the AIS, to, say, a VHF etc.

Sorry about delayed response!
Thanks for explaining the GPS rules. Although I like the look of, and ease of mounting (under a shelf next to the VHF) of the Comar, I guess the Em-trak is the way to go. I don't really want to have to find somewhere to fit a GPS antenna and route cable to it.
Thanks.

 

[Roberto]

In what area are you sailing, or likely to sail?

 

[mikefleetwood]

In what area are you sailing, or likely to sail?

Mostly SW UK, specifically Cornwall.

 

[jwilson]

I bought and fitted the Emtrak B953 in late 2021: easy to install, worked very well connected to two plotters, one NMEA2000 and one NMEA0183. It did go wrong summer 2022, but Emtrak quickly repaired it, and no more trouble since.

 

[chris-s]

We added an Onwa KS200A B+ transponder from Aves Marine earlier this year for about £300 and can’t fault it.

 

[PaulRainbow]

We added an Onwa KS200A B+ transponder from Aves Marine earlier this year for about £300 and can’t fault it.

For the £299 you get no GPS antenna and no VHF antenna or splitter, add those and the price goes up to £483.80

You the have to fit two external antennas, or swap the VHF antenna for a slitter, which takes the price up to £563.80

NMEA 0183 only, no USB or NMEA 2000 (so won't connect to most modern plotters without a converter), no multiplexing etc

 

[Phil_boat]

NMEA 0183 only, no USB or NMEA 2000 (so won't connect to most modern plotters without a converter), no multiplexing etc

The newer B+ version has NMEA2000 and WiFi

 

[PaulRainbow]

The newer B+ version has NMEA2000 and WiFi

Yes, but it isn't £299, like the one quoted in post #13

It's all well and good people making price comparisons, but the products have to be like for like to mean anything.