AIS help please - and DO NOT BUY MCMURDO AIS

[Elessar]

I have a McMurdo AIS as part of my mostly raymarine system.

Bought new (most of my nav is ex ebay) I regretted buying it from the start. It was a few £££ cheaper than the raymarine one but it was false economy.

The software came on CD. I have no devices that will accept a CD and there are no downloadable files on their website. I got it from them via FTP after a week or so and installed the 1990s style software.

It can supposedly lake lat/long via NMEA2000 but it doesn't work. I had to use the internal GPS and fit the (supplied) antenna to do so.

It was receiving but not transmitting. Force 4 supplied it with a VHF splitter but I realised it splits for receive only and not transmit.

I fitted a second VHF antenna therefore. A stubby RIB style one.

Now it transmits only occasionally and it receives only up to about 500m. I have swapped the VHF and AIS aerials over, the VHF still transmits and the AIS is still V short range.

Apart from doing a float test and buying a better one, has anyone got any bright ideas about how I might further troubleshoot? By float test I mean chucking it over the side......

 

[david_bagshaw]

most have the same chip in them by SRT and are configured using pro ais2.
the above prog has a handy test feature for checking applied voltage, but very useful VSWR section to check the vhf Ariel. Most likely to be your installation....

 

[john_morris_uk]

It’s a requirement of the AIS set up that it has a separate GPS. (Certainly for commercial use it is; not sure about pleasure use?)
The splitter needs to be an active powered one. (We run all Raymarine stuff and the splitter, despite my reservations, works extremely well).
Did you damage rx/ tx in your AIS with the use of the incorrect splitter?

 

[Momac]

How do you know how often if transmits and at what intervals is it transmitting and at what boat speed?
If the boat is moored it will ony tx at intervals of several minutes.
Maybe try a different antenna

 

[Hurricane]

AIS Class B doesn't transmit very often anyway, especially if you are in a congested AIS area.
The new Class B spec (Class B Plus) will transmit far more often than the old version.

Taking @john_morris_uk point, maybe there isn't much wrong with your unit.
The GPS feed is important - not only to give it position, but the GPS feed uses "accurate satellite time" to synchronise the AIS's transmission.
As you may know, AIS is all about transmitting withing "time slots" so it won't transmit without a proper GPS time input.

Anyway if you are thinking of giving up on it, have a look at a Class B Plus unit.
The Class B Plus units, not only transmit more often, but also transmit a more powerful signal.
Also, don't cut corners on the antenna.
These days, satellites are also receiving AIS signals and the Class B Plus units are supposed to be WAY better at being picked up by satellites.
In fact, I read somewhere that the old Class B can't be picked up by satellite.

All in all - if you are buying new - make sure that it is a Class B Plus

Not much help to you but, to test AIS in SCM, I use a local AIS receive station that I built myself from a Raspberry Pi.
My Raspberry Pi AIS station runs 24/7 and is located on the roof of the SCM marina building.
It streams the AIS data that it receives into Marine Traffic, Vesselfinder and AIS Hub.
These streams give a good indication if a system is transmitting or not.
Here is a live feed from my Raspberry Pi AIS receiver - you might have to zoom into SCM to see all the current transmissions.
Details for AIS Station Sant Carles Marina, Spain - VesselFinder
Without a facility like that, I expect that you have been using another boat to monitor the AIS.
With the old Class B AIS units, if you miss a transmission, you may have to wait as long as 3 minutes before you get another "time slot" for your system to transmit.

 

[Elessar]

It’s a requirement of the AIS set up that it has a separate GPS. (Certainly for commercial use it is; not sure about pleasure use?)
The splitter needs to be an active powered one. (We run all Raymarine stuff and the splitter, despite my reservations, works extremely well).
Did you damage rx/ tx in your AIS with the use of the incorrect splitter?

Did the splitter cause damage is something I hadn’t considered but is a great question. Don’t know how to test for it though.

 

[Elessar]

How do you know how often if transmits and at what intervals is it transmitting and at what boat speed?
If the boat is moored it will ony tx at intervals of several minutes.
Maybe try a different antenna

Friends boat reporting and marine traffic.
Currently saying last seen in st Peter port and I’ve done 17 hours since then and it’s not transmitted.

By swapping with the VHF I have tried 2 antennae.

 

[Elessar]

most have the same chip in them by SRT and are configured using pro ais2.
the above prog has a handy test feature for checking applied voltage, but very useful VSWR section to check the vhf Ariel. Most likely to be your installation....

This sounds interesting. How to I get / use pro AIS2. The mc Murdo software is laughable. Reminds me of black screens with green text.

 

[Elessar]

AIS Class B doesn't transmit very often anyway, especially if you are in a congested AIS area.
The new Class B spec (Class B Plus) will transmit far more often than the old version.

Taking @john_morris_uk point, maybe there isn't much wrong with your unit.
The GPS feed is important - not only to give it position, but the GPS feed uses "accurate satellite time" to synchronise the AIS's transmission.
As you may know, AIS is all about transmitting withing "time slots" so it won't transmit without a proper GPS time input.

Anyway if you are thinking of giving up on it, have a look at a Class B Plus unit.
The Class B Plus units, not only transmit more often, but also transmit a more powerful signal.
Also, don't cut corners on the antenna.
These days, satellites are also receiving AIS signals and the Class B Plus units are supposed to be WAY better at being picked up by satellites.
In fact, I read somewhere that the old Class B can't be picked up by satellite.

All in all - if you are buying new - make sure that it is a Class B Plus

Not much help to you but, to test AIS in SCM, I use a local AIS receive station that I built myself from a Raspberry Pi.
My Raspberry Pi AIS station runs 24/7 and is located on the roof of the SCM marina building.
It streams the AIS data that it receives into Marine Traffic, Vesselfinder and AIS Hub.
These streams give a good indication if a system is transmitting or not.
Here is a live feed from my Raspberry Pi AIS receiver - you might have to zoom into SCM to see all the current transmissions.
Details for AIS Station Sant Carles Marina, Spain - VesselFinder
Without a facility like that, I expect that you have been using another boat to monitor the AIS.

Thank you.

 

[Hurricane]

Thank you.

Sorry, I've been editing my post
A added this at the end - which is probably important:-
With the old Class B AIS units, if you miss a transmission, you may have to wait as long as 3 minutes before you get another "time slot" for your system to transmit.

 

[Elessar]

Sorry, I've been editing my post
A added this at the end - which is probably important:-
With the old Class B AIS units, if you miss a transmission, you may have to wait as long as 3 minutes before you get another "time slot" for your system to transmit.

Yes that’s long I’ve moved a long way in three minutes.
I’d bite the bullet and buy a B+ but if I have got an installation problem that would be annoying!

 

[Momac]

I find Marinetraffic a bit hit and miss and it loses us when we go up river much earlier than in the past.
I think they have turned off any satellite data or somehow dumbed it down . Perhaps its better if you pay. Not just me but I looked up another boat and it was much the same .

However if you are with another boat and they are reporting issues that's a different matter.

The programming software is probably all the same regardless of the brand. All you are really doing is inputting mmsi and boat data . So you could try the Raymarine programming software for example. I dare say it will make no difference but what do you have to lose .

If the goods are faulty don't you have rights even if you did buy on ebay?

 

[Elessar]

I find Marinetraffic a bit hit and miss and it loses us when we go up river much earlier than in the past.
I think they have turned off any satellite data or somehow dumbed it down . Perhaps its better if you pay. Not just me but I looked up another boat and it was much the same .

However if you are with another boat and they are reporting issues that's a different matter.

The programming software is probably all the same regardless of the brand. All you are really doing is inputting mmsi and boat data . So you could try the Raymarine programming software for example. I dare say it will make no difference but what do you have to lose .

If the goods are faulty don't you have rights even if you did buy on ebay?

Thanks will give it a go. As you say nothing to lose.

Over a year old now so I don’t think they’d be interested. Should have chased it sooner but AIS isn’t that useful in the solent and it was just another item on the to do list.

I’ve just come back from a cross channel trip and I was back to hand bearing compass for ship avoidance making me want to fix it.

 

[Commercial Dave]

I find Marinetraffic a bit hit and miss and it loses us when we go up river much earlier than in the past.
I think they have turned off any satellite data or somehow dumbed it down . Perhaps its better if you pay. Not just me but I looked up another boat and it was much the same .

It's down to the quality of your AIS transmissions and also the quality of the terrestrial AIS coverage in the area you are operating in. There are many factors that influence the quality of your transmissions, mainly these are what type of unit you are running (class A / class B+ / class B), what aerial you are using (is it a dedicated aerial specifically tuned for AIS or are you sharing an aerial with your VHF through a splitter), the length and type of coax cable connecting the transceiver to the aerial (is it 5 metres of quality coax or 25 metres of something shit like RG-58), the height of the aerial on the boat (is it 2 metres above the waterline or 20 metres above), the proximity of the aerial to other aerials / structures etc.

Marinetraffic and other vessel tracking websites rely entirely on data submitted to them by people that run AIS receivers connected to the internet, most of these are on land although it is possible to connect a transceiver onboard a vessel to the internet if you have the right equipment, knowledge and of course an internet connection.

They do of course also have satellites which can receive AIS now although these are almost all owned and operated by one or two companies who then sell the data to Marinetraffic etc, but as a result you cannot see satellite AIS data on marinetraffic unless you also pay a (very expensive) subscription.

Most vessel AIS transmissions can be received by satellite but obviously the success rate mostly depends on the above factors too, e.g. a class A unit with a massive high gain aerial is much more likely to be received than a class B unit with a tiny aerial. Remember that the satellites have a massive footprint and can easily see tens of thousands of boats at any time and will receive a lot of overlapping transmissions.

 

[Martin_J]

As others have said, you really need to either test both antennas and/or connect a laptop (with ProAIS2) software into the unit to see what the M10 itself is actually seeing in the way of antenna quality before trashing the McMurdo brand.

Software seems to be available on the DigitalYacht, the Comar and the Raymarine websites.

Useful download at the link below to help with deciphering the forward and reverse power numbers... you really need the good forward power and very little power coming back (as could be tested with a separate antenna analyser or SWR meter.)

Tech 00011 2011 Fault Finding Class B Transponders Pdf - Digital Yacht America

Old photo below showing example from my M10 a number of years ago shows forward and reverse power (158 and 13) can be well within spec..

 

[Martin_J]

As to the question about whether or not it could get GPS position from other kit on your NMEA2000 backbone... Transponders can't.. They have to rely on their inbuilt GPS receivers with their dedicated antenna.

If they could work off an NMEA2000 input it would be rather too easy to modify your position data and make yourself appear where you're not.

 

[Hurricane]

As to the question about whether or not it could get GPS position from other kit on your NMEA2000 backbone... Transponders can't.. They have to rely on their inbuilt GPS receivers with their dedicated antenna.

If they could work off an NMEA2000 input it would be rather too easy to modify your position data and make yourself appear where you're not.

Yes but I don't think it is for that reason.
I think it is because the transponder needs very a accurate clock in order to schedule its transmissions into a specific time slot.
GPS time, of course, is available on a GPS satellite but after putting a GPS signal through a NMEA stream, you would loose that extremely accurate clock that a dedicated GPS receiver would provide,

 

[Elessar]

As others have said, you really need to either test both antennas and/or connect a laptop (with ProAIS2) software into the unit to see what the M10 itself is actually seeing in the way of antenna quality before trashing the McMurdo brand.

Software seems to be available on the DigitalYacht, the Comar and the Raymarine websites.

Useful download at the link below to help with deciphering the forward and reverse power numbers... you really need the good forward power and very little power coming back (as could be tested with a separate antenna analyser or SWR meter.)

Tech 00011 2011 Fault Finding Class B Transponders Pdf - Digital Yacht America

Old photo below showing example from my M10 a number of years ago shows forward and reverse power (158 and 13) can be well within spec..

View attachment 142198

I’m trashing the brand because the software came on (useless) CD and their support was woeful. I expect it to come with software that allows it to be useable. When I eventually got the software it was embarrassingly old school.

I accept the installation may be at fault re the transmissions. But the Mc Murdo software doesn’t help with fault finding.

Thanks for the tips.

 

[Elessar]

As to the question about whether or not it could get GPS position from other kit on your NMEA2000 backbone... Transponders can't.. They have to rely on their inbuilt GPS receivers with their dedicated antenna.

If they could work off an NMEA2000 input it would be rather too easy to modify your position data and make yourself appear where you're not.

Their instructions contradict this.

When I disconnect the GPS antenna and have a valid NMEA2000 connection it just doesn’t work.

 

[Martin_J]

I must admit that it is odd that they don't seem to have put the ProAIS software on their website when many of the other AIS manufacturers have done...