Anybody have a JRC 1500 radar?

Bav34

Bav34

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Simple question. The difficult one is on another post.

When I have an EBL and (through the joystick control) try to change from relative to compass the number stays relative!

Does yours change?

Thanks.
 
Its because you are not inputting ships bearing through NMEA input. Apologies if you are ... so ... check input bearing sentence agrees with what JRC will accept.
 
wot ??????????????????

all I do is turn it on /forums/images/graemlins/blush.gif /forums/images/graemlins/blush.gif
 
what para is saying, is unless the radar knows what direction you are heading in, it can only ever give a relative bearing, not a compass bearing.....

It knows what direction you are heading in from an input called NMEA, usually from either a GPS or a gyro compass.... (gyro compass better)..

Your radar may well have this connection either not in place at all, or in place, but not working properly....

until this is fixed, then you'll not get anything other than relative bearings...
 
Ta. Saw '' check input bearing sentence'' and went into a coma /forums/images/graemlins/ooo.gif

There must be a GPS inerface cos the radar screen shows waypoints. Interesting !
 
As an aside, I have an NMEA input from a compass into my radar, as I did on the last boat, but just got used to using relative bearings, ie in head up...... its a good habit, as it allows you to make better decisions as to avoiding action IMHO, and you soon get used to it..... v simple really... under Rule 19 restricted visibility, turn to starboard in all cases of a contact appearing on the radar screen that presents a collision risk, unless the contact is in the bottom right quadrant and then turn to port, and you'll always be complying.....
 
if memory serves correct, there's a priority input rule which if the heading sentence (HDG) is not present, it defaults to COG so what you are seeing is the bearing of the waypoint relative to the COG. GPS will never output heading info, you'll need an electronic compass, eg the one attached to the autopilot, for that.
 
Another thought - if you are using GPS and you were at anchor (looking at your other thread) you may not have had a CoG being calculated by the GPS or output by it. Unfortunately you need to look at the sentences output by the GPS and accepted by the Radar - never tried my JRC1500 when at anchor but know that I don't get a COG until moving from GPS on the cockpit repeater.

Also beware if you do use Course Up OR Relative Bearings with input from the GPS in strong cross tide conditions, the radar will assume that CoG is thru the Water and the bearing given will out by the difference between COG and where the bows are pointing. Use relative bearings and no input in these conditions (i have a switch in the NMEA input) or better still use a fluxgate compass for heading input.
 
If you are going to use the radar for collision avoidance (like most users) it should be Head Up. Look for a 1 day RYA course, you will be much better equipped to use the set. Radar is the least user friendly box on the boat.
 
That\'s right...

[ QUOTE ]
Unless I'm very much mistaken the JRC1500 doesn't support North Up , only Head(ing) Up.

[/ QUOTE ]You're right, the 1500 only gives a Head-Up display. It needs a compass input to give magnetic headings on the EBL.
 
Re: That\'s right...

That's the answer then. Back to the scary 360 + or - bearing , + or - our heading ...... whilst calculating 5 CPA's at the same time .. .... we're doomed !!!!!

Thanks to all.
 
Re: That\'s right...

I'm not radared, so don't have much of a clue what you're talking about, but I can't help wonderinmg if there's not some mechanical solution, a la Blue Peter. involving a one arm protractor and an extra arm.

10560_LRG.jpg
 
Re: That\'s right...

If there is a GPS connected then the radar display will default to course up, not head up, (the unit will not inform you of this) and you are not able to alter this; EBL will be relative to COG.

If you have a yeoman plotter, using the yeoman radar plotting function you are able to locate the position, COG and speed of any number of targets and record this info on a paper chart , if you then draw a line on the chart that indicates your COG you get a very good idea of your current situation.
 
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