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How often do you guys use MARPA? I have played with it a few times but haven't used it much. Last week I was running in Block Island sound in some thick fog, and knew I was around some other boats and in a fishing area, so I used it and relied on it. It actually worked awesome!! In the below pics, you can see a bit out the windshield I was in thick white fog, and you cna see 3 marpa targets, 1 drifting at 1 knot, another cruseing at 13 knots, and one trolling at 4 knots. You get their heading and speed which is awesome. When the display calculates a crash course, it notifies you with a sunken boat symbol, and when you get in close range (you set the range), it pops up and beeps to tell you. Very cool stuff.
I've tried using MARPA quite a few times on my Raymarine C80. It has almost never been able to accurately calculate the actual course and speed of the target, seemingly due to my own speed and course. I thought it was supposed to figure all that out based on relative angles and speed. Apparently not.
__________________ Captain Ethan Maass Sea Tow South Shore M a s s a c h u s e t t s
Serving Cape Cod Bay and offshore
I've tried using MARPA quite a few times on my Raymarine C80. It has almost never been able to accurately calculate the actual course and speed of the target, seemingly due to my own speed and course. I thought it was supposed to figure all that out based on relative angles and speed. Apparently not.
What heading sensor are you using? I think Birdmans is connected to his Garmin Autopilot which is a perfect match for his set up. I have mine connected to a KVH Autocomp 1000 which works awesome on my Garmin Radar and tracks and gives heading info on targets. I also read on THT that a heading sensor must update very quickly . I tried to find that thread but could not find it. I bet if you asked Glen or Tom (Blue Water Pilot) they could help you out.
That's a good question. A heading sensor not advertised as being necessary for MARPA to work on Raymarine's displays. However, I'll bet that MARPA will work better with a heading sensor.
My C80 is connected to a Raymarine S1000 autopilot, which I think is supposed to have a rudimentary, but not very good, heading sensor integrated into the autopilot. Maybe that's not enough to get decent MARPA results.
__________________ Captain Ethan Maass Sea Tow South Shore M a s s a c h u s e t t s
Serving Cape Cod Bay and offshore
Yep, that's it. I do have the Garmin AP installed, which is supplying fast and "rated" heading data to the display. The calc'd speed and heading data it's showsing was dead on. I had a few boats cross my path, as well as run along side me and also behind me for a while, and those were all dead on (since they were verifyable).
The s1000 does not ouput a fast or rated heading, so that won't work. The KVH 1000 is an awesome unit, and does and will work. Ethan, throw on a KVH and you'll be very happy. It will also greatly improve the radar overlay on your c80.
Here's another shot, showing the fog a bit better and why I was using it, I was running 3100+ RPM's which is about 25 or 26 knots:
Here's a shot of what it looks like when it is aquireing the target. You click Menu, then Aquire targete and click on or near the actual target and then see the rings you see around the target, and they are blinking/flashing for a few seconds while it calculates the targets speed and heading. Cool stuff:
Sea Tow Ethan, S1000 don't have a heading sensor, its steering based on GPS. I expect it has an accelerometer installed, but this will not improve your radar overlay.
I have a Maretron SSC200 as radar heading sensor connected to my E80, and the MARPA performance is super. SSC2000 will give better heading info than KVH since the the Maretron has rategyros and accelerometers in addition to the compass. I guess the output from the Garmin pilot is comparable to SSC200.
I have to agree, MARPA can be an extremely usefull feature. The boat I fish on has a Navnet 3D that has a 30 target ARPA (not Marpa) so it is automatic. We set up a zone when night fishing and track any boat automatically that comes into the area.
I can do that as well. Or, also add in an alarm zone. which puts a ring around the boat (or in front of the boat, you define it) at a set distance and the alarm goes off if any target enters that area.
That stuff would be nice when offshore, but inshore it's a PIA, because every little crab pot sets it off....
Neither my RM nor Garmin radar displays will enable MARPA if there is no valid heading sensor. It is absolutely required.
I use it all the time, especially offshore to keep track of tankers and large ships.Ypu would be surprised how fast some of those ships are.
It's also useful while fishing, especially trolling to keep an eye on what speeds other boats are traveling. If you aren't hooking up at 8 knots, but the other guys are hooking up at 4, well, you probably want to know that.
One more thing, there are two settings. Relative and absolute speeds/direction. If you specify relative, the values will take your speed into account, absolute will tell you their true speed.
__________________
Terry Jason 35, Yanmar 370 hp, Lots of fun at a leisurely pace
That's confusing. My Raymarine C80 does in fact acquire MARPA targets.
Don't know, but my R80 wouldn't engage any MARPA functionality without a heading sensor, specifically HDG NMEA sentances. My Garmin won't do it either. It might be getting false hdg data from somewhere, or maybe it's a sw upgrade.
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Terry Jason 35, Yanmar 370 hp, Lots of fun at a leisurely pace
I use it all the time, especially offshore to keep track of tankers and large ships.Ypu would be surprised how fast some of those ships are.
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It is even better when you run it offshore with an AIS receiver. I run mine with the Nauticast B, which lets you seperate out the big ships from the recreational guys - naturally big ships are more of a concern.
As far as Raymarine products go both radar overlay and MARPA will appear to work without heading sensor. But for them to work properly, and the overlay to be accurate you must have a heading sensor installed and calibrated.
__________________ Capt. Tom Pitasi
Coastal Fishing Charters www.fish-ct.com
Raymarine Pro Ambassador
Lunker City Pro Staff
Orvis Endorsed Fly Fishing Guide
Radar usage: MARPA ?? 
