HDS radar and chart overlay do not line up

[Dave_E]

Hi All,

I have a Lowrance 3G radar, a Lowrance HDS 9 and a Lowrance Point 1 GPS. I had all these on a sailboat 3 years ago, and moved it all to the trawler. After I hooked everything up, all works fine individually, however when I overlay the radar onto the chart... the radar hits don't align with items, like a piling. I've got nothing from the instruction manuals. Any suggestions or comments? Thanks.

Dave

 

[twistedtree]

There are a number of possibilities.


When you reinstalled the radar, did you physically align it with the fore-aft line of the boat? Then after doing that, you need to adjust it through the setup menus. This let's you really dial it in. It's usually done as part of a sea trial by getting heading the boat straight at something that is also easily identified on the radar. You then add/subtract to the heading until the radar image is dead ahead at the same time you are actually heading at the target. This can be trick if there are any seas. The installation manual usually outlines the steps.


If you already did all that, then I'd start looking at what heading sources are being used by the plotter and the radar. Both should be using a heading sensor, not the GPS COG. And using the same sensor if there are two.


Let us know, and we can take it from there.

 

[MacPhid]

I recall there is a calibration procedure for the point 1 compass/gps. You can run it from the chart plotter if I remember correctly. The point 1 needs to be calibrated to allow overlaying the radar.
James