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Go Back   SailNet Community > On Board > Gear & Maintenance > Electronics
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  #1  
Old 09-13-2011
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Radar newbie communication question

Getting ready to do some offshore sailing I'm thinking I need at least low end radar. My central nav system is GPS-NavX which I'm pretty happy with, but doesn't integrate directly into a radar, though it can read NMEA 0183 code. I am looking at either a low end Furano system that comes with a monochrome plotter, or getting a compatible plotter used and adding the radome to match.

What I am hung up on is how communication happens between the radome and the plotter. Does the scanner send data through NMEA-0183, and the plotter parses these sentences? Or does the scanner send some other kind of raw data for the plotter to interpret.

One question is whether I can just about any scanner and plotter and expect them to communicate (at least if they are both from the same manufacturer), or is there some non-simple communication going on?

Thanks!

Dennis
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Old 09-13-2011
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Whenever RADAR is on a vessel it changes the "Who is at fault" situation in case of an unfortunate occurrence. In case this happens have a hammer near to break the array so you can claim the RADAR was not functional at the time of the incident. Liability is covered in Inland Harbor Rules, International Rules, Great Lakes and Western Rivers Rules.
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Old 09-13-2011
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Quote:
Originally Posted by apogee1mars View Post
Whenever RADAR is on a vessel it changes the "Who is at fault" situation in case of an unfortunate occurrence. In case this happens have a hammer near to break the array so you can claim the RADAR was not functional at the time of the incident. Liability is covered in Inland Harbor Rules, International Rules, Great Lakes and Western Rivers Rules.
This is NOT TRUE and you are making some major assumptions with this post.

Any and all boats are required to use every aid available to them to avoid a collision. So, if you have radar and you do not use it you well could be found at fault.

HOWEVER, if someone has radar and doesn't use it, they're kind of an idiot anyway IMO


and... sometimes collisions happen even with radar and it is not an automatic liability to have it, in fact if you identify the other boat on radar and try to evade and they still hit you it only strengthens your case legally.

in any case; not buying radar because it increases the odds you will be held accountable for your actions, VS having another tool at your disposal to actually prevent an accident in the first place seems like a silly debate if you ask me.


As to the OP, just make sure you have a radar with MARPA. I'm not 100% sure but I think it just sends the coordinates via NMEA just like AIS does. But I'd suggest firing off an email to the NavX developer. He's very responsive and extremely knowledgeable (and friendly too!)
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Old 09-14-2011
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Quote:
Originally Posted by dtempleton View Post
Getting ready to do some offshore sailing I'm thinking I need at least low end radar. My central nav system is GPS-NavX which I'm pretty happy with, but doesn't integrate directly into a radar, though it can read NMEA 0183 code. I am looking at either a low end Furano system that comes with a monochrome plotter, or getting a compatible plotter used and adding the radome to match.

What I am hung up on is how communication happens between the radome and the plotter. Does the scanner send data through NMEA-0183, and the plotter parses these sentences? Or does the scanner send some other kind of raw data for the plotter to interpret.

One question is whether I can just about any scanner and plotter and expect them to communicate (at least if they are both from the same manufacturer), or is there some non-simple communication going on?

Thanks!

Dennis
Dennis--

I'm not an electronics person so I cannot speak to your communication question particularly well. However, our radar is an older Raytheon R-20x, which of course has a display separate and apart from our Garmin 2006c plotter (at the nav table), and the Garmin has no difficulty passing heading and way-point data to the radar via 0183. If a way-point is within range the radar draws a circle around it (if way-point mode is selected) and when under way, heading data on the radar display is taken from the GPS. Although we cannot "overlay" radar returns on our plotter, when the scales are relatively similar on both displays, I/we do not have difficulty discerning their relationship.

Frankly, I do not like the idea of having all of our Nav data displayed on a single screen as I don't like the idea of having all of our eggs in one basket.

FWIW...
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Old 09-14-2011
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Quote:
Originally Posted by dtempleton View Post
Getting ready to do some offshore sailing I'm thinking I need at least low end radar. My central nav system is GPS-NavX which I'm pretty happy with, but doesn't integrate directly into a radar, though it can read NMEA 0183 code. I am looking at either a low end Furano system that comes with a monochrome plotter, or getting a compatible plotter used and adding the radome to match.

What I am hung up on is how communication happens between the radome and the plotter. Does the scanner send data through NMEA-0183, and the plotter parses these sentences? Or does the scanner send some other kind of raw data for the plotter to interpret.

One question is whether I can just about any scanner and plotter and expect them to communicate (at least if they are both from the same manufacturer), or is there some non-simple communication going on?

Thanks!

Dennis
Neither nmea 0183 nor nmea 2000 can be used to send data from the radar antenna to the display.
For older radars the processing of the signals from the antenna are processed in the display unit.

Newer models have moved the processing into the radar unit, these are designed to be used with MFD's (Multi Function Display). They need a high bandwidt conection between the antenna and the MFD.

The new Furuno sets that are beeing used with the Navnet3D series are using ethernet with a proprietary protocol on top.
The MaxSea PC software (owned by Furuno) can also display the radar picture.

Other new designs use similar solutions.
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Old 09-14-2011
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Quote:
Originally Posted by xymotic View Post
This is NOT TRUE and you are making some major assumptions with this post.

It is not an assumption

Any and all boats are required to use every aid available to them to avoid a collision. So, if you have radar and you do not use it you well could be found at fault.

This is true and is the sticking point.

HOWEVER, if someone has radar and doesn't use it, they're kind of an idiot anyway IMO

I am a RADAR advocate. I really like it when all of my electronics interface and I can have automatic collision avoidance, slipped anchor etc.

and... sometimes collisions happen even with radar and it is not an automatic liability to have it, in fact if you identify the other boat on radar and try to evade and they still hit you it only strengthens your case legally.

Not necessarily. Due to the verbiage of the Rules of the road on "The burdened vessel" The vessel positions and who is required to make an international turn to avoid a collision becomes ambiguous. Have an intact RADAR in such a case can further liability per maritime law.

in any case; not buying radar because it increases the odds you will be held accountable for your actions, VS having another tool at your disposal to actually prevent an accident in the first place seems like a silly debate if you ask me.

Never leave home without one is my stance. A couple of EPIRBS with a self departing raft are way up on the list too. I am not advocating NOT buying a RADAR because of potential liability (that would be silly), I am just saying keep a hammer around.



As to the OP, just make sure you have a radar with MARPA. I'm not 100% sure but I think it just sends the coordinates via NMEA just like AIS does. But I'd suggest firing off an email to the NavX developer. He's very responsive and extremely knowledgeable (and friendly too!)
Today's electronics are PFM.
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Old 09-14-2011
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Quote:
Originally Posted by apogee1mars View Post
Today's electronics are PFM.
The assumption is that you are assuming it would not be used

Liability is only increased if you also increase your own negligence.

Not only is it just plain bad advice, but the hammer 'trick' would open you up to far more liability, some of which would be criminal such as falsifying reports, lying under oath, interfering with an investigation and if it's the coast guard lying to a federal official.

And not for nothing, but if anyone EVER put together your post(s) advocating such and tied it to you in court,it would not take too clever of an attorney to have you found at fault for just about any collision, radar related or not

Last edited by xymotic; 09-14-2011 at 12:20 PM.
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The "Hammer" is figurative speech only. It is what it is when it is time to go to a Maritime court proceeding.
The rules of the road right away laws are hard for me to decipher. The two point abaft of beam stuff, or converging azimuths. Heck, I know this is old but look at the Andrea Doria, Stocholm sinking and what was derived from RADAR. There was a USCG mishap that took place off of Newport Beach CA years ago that ended up with the CG cutter going down after a collision with a private motor yacht. Broad daylight, RADARS radaring. Otto steering the private boat while the skipper was on the foredeck with a little wine, cheese, and Gretchen. Cutter converging from the starboard. Take a guess who got hung?


PS Aaron I bought a PA24-260 out of Reno a couple of years back

Last edited by apogee1mars; 09-14-2011 at 06:44 PM.
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Old 09-14-2011
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Originally Posted by xymotic View Post
....if anyone EVER put together your post(s) advocating such and tied it to you in court,it would not take too clever of an attorney to have you found at fault for just about any collision, radar related or not
I think I will worry about getting hit with a meteor first...
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Old 09-14-2011
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Quote:
Originally Posted by knuterikt View Post
Neither nmea 0183 nor nmea 2000 can be used to send data from the radar antenna to the display.
For older radars the processing of the signals from the antenna are processed in the display unit.

Newer models have moved the processing into the radar unit, these are designed to be used with MFD's (Multi Function Display). They need a high bandwidt conection between the antenna and the MFD.

The new Furuno sets that are beeing used with the Navnet3D series are using ethernet with a proprietary protocol on top.
The MaxSea PC software (owned by Furuno) can also display the radar picture.

Other new designs use similar solutions.
This is true and also a little misleading. The OP is talking about a stand-alone radar with a display. These units ARE capable of tracking a target, and then sending that data to any other brand of MFD or laptop.

It will not show the actual 'sweep' of the radar but when you select a target it will continue tracking it.
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