Problem getting MARPA with Raymarine Axiom and Quantum Radar

[DavidJ]

I can’t get a MARPA fix and reading a thread on the Raymarine forum they seem to suggest needing a Raymarine AR200 Augmented Reality Sensor at £500….No way!
Bit annoying because my 20 year old RC70 and analogue radar would pick up MARPA a treat with no additional stuff.
Of course you guys with autopilots would have something like this anyway but I don’t.
Any of you managing MARPA with my setup?
Any suggestions for a cheap fix for me. I only want it to play with.

 

[Hurricane]

What are you expecting MARPA to do?
AFAIK MARPA is just a tracking aid.
We use it to track other vessels.
To be accurate, it does need a good heading sensor but even a cheap one that you should have already fitted should work.

This week, our AIS system was a bit dodgy so I used MARPA instead.
Our system is a bit more complex but once MARPA had "locked on" to a target, it makes the information available on the NMEA interface where OpenCPN can display it.
Here's an example from this week



The round green blob is the MARPA target.
Red boat is us.
The two small blue dots are where both boats will be when CPA (Closest Point Arrival).
We used this example to meet a friend during our passage home.
A kind of "engineered crash"

 

[DavidJ]

I have no real genuine use for MARPA but just a bit irritating that I had it on my 20 year old setup and after upgrading, I don’t seem to be able to access it without an additional £500 10Hz heading sensor AR200.
It seems from the Raymarine forum with answers from a Raymarine moderator (Chuck) that other folk have the same issue.
It might be something to do with the Lighthouse 3 software.
I‘m thinking there must be some NMEA 0813 third party device that I can plug into my backbone which will do the trick cheaply. However unless I can simply plug this thing into my existing Seatalk converter it’s a bit beyond my pay grade.
Great use of MARPA to join up with another vessel. In fact this afternoon I watched a Raymarine YouTube video and apparently in the menu there is an item just for doing that which was designed for US Customs interceptions.

 

[kwb78]

MARPA requires a decent heading source so that the plotter can reference the radar data to the real location. Without it there’s no way for it to get a real bearing to target or to track the motion of the vessel. You don’t necessarily have to use the AR200, as although that is a high speed heading source it’s mainly intended for video stabilisation and augmented reality overlays on camera feeds. The EV-1 sensor which is part of the evolution autopilot also provides suitable heading data.

You could use some other third party sensor as long as it provides data to the plotter. I don’t know if the axiom plotters require a 10Hz source to calculate a MARPA fix, but slower heading sensors probably won’t work very well in anything other than a flat calm anyway because the heading will always be chasing the motion of the boat. If you use the radar overlay on the chart then the slower sensor would be very apparent as the boat moves as the radar returns will not properly line up with the chart.

 

[DavidJ]

MARPA requires a decent heading source so that the plotter can reference the radar data to the real location. Without it there’s no way for it to get a real bearing to target or to track the motion of the vessel. You don’t necessarily have to use the AR200, as although that is a high speed heading source it’s mainly intended for video stabilisation and augmented reality overlays on camera feeds. The EV-1 sensor which is part of the evolution autopilot also provides suitable heading data.

You could use some other third party sensor as long as it provides data to the plotter. I don’t know if the axiom plotters require a 10Hz source to calculate a MARPA fix, but slower heading sensors probably won’t work very well in anything other than a flat calm anyway because the heading will always be chasing the motion of the boat. If you use the radar overlay on the chart then the slower sensor would be very apparent as the boat moves as the radar returns will not properly line up with the chart.

Thanks for your very clear reply.
I‘ve never tried the overlay but I suspect without an AR200 or similar it may be disappointing if it works at all.
With the overlay potential you have given me another reason for biting the bullet and buying the AR200. I notice that the EV-1 is even more expensive at £790
Thanks

 

[kwb78]

Yes the EV-1 is more expensive, but it is the controller part of the Evolution autopilot system as well as the heading sensor. It is usually a lot cheaper (per component) to buy them as a package rather than the individual components, so if the addition of or upgrade to an autopilot might be on the horizon in the future some time that might be worth considering. The AR200 serves no purpose for the autopilot system despite being a heading sensor, so it would be a duplication of cost if you wanted to go down that road.

There are other 10Hz heading sensors available, such as the Digital Yacht HSC100 or the Garmin GPS 24xd (which is also a GPS receiver) which cost less than the AR200 - I have no personal experience of either, so don't take it as a recommendation but it might be worth looking in to. The other thing to consider with using a third party sensor is that you have to connect such a device to your network and be able to calibrate it - there is often a way to do it without having a same manufacturer MFD, but you can't usually use a third party display to do it.

 

[DavidJ]

Yes the EV-1 is more expensive, but it is the controller part of the Evolution autopilot system as well as the heading sensor. It is usually a lot cheaper (per component) to buy them as a package rather than the individual components, so if the addition of or upgrade to an autopilot might be on the horizon in the future some time that might be worth considering. The AR200 serves no purpose for the autopilot system despite being a heading sensor, so it would be a duplication of cost if you wanted to go down that road.

There are other 10Hz heading sensors available, such as the Digital Yacht HSC100 or the Garmin GPS 24xd (which is also a GPS receiver) which cost less than the AR200 - I have no personal experience of either, so don't take it as a recommendation but it might be worth looking in to. The other thing to consider with using a third party sensor is that you have to connect such a device to your network and be able to calibrate it - there is often a way to do it without having a same manufacturer MFD, but you can't usually use a third party display to do it.

Good point about the EV-1, I’m learning all the time. I don’t intend to fit an autopilot but one can never say never and since this is my boat for life it is a consideration.
I‘ve just looked at the HSC100 and at £300 it would be a solution. I’m just a bit wary of the bundle of wires but these things are generally well documented and I’ve wired up non standard GPS units successfully.
Really appreciate your help with this
Thanks