Strange Behaviour



My MFD 12 shows some really strange trails.In this shot, I was motoring towards the pier on the right when the display suddenly moved me to the center of the pier on the left and back in an instant with the resulting track. I did not go there.
In the second shot, the boat was tied up at a pier. The tracks blue show random movements toward the bottom left as well as a few to the right of the screen
Anyone have any idea what's going on?
Based on the screen shots, I would have to say you are receiving some interference either from something on the boat or surrounding area. The GPS signal DOP (Dilution of precision) is most likely increasing. For example, we have had some recent reports in the Charleston area (city harbor) that a local WIFI booster that someone has installed was/is causing boaters problems with their GPS signal. I would recommend you ensure that you don’t have anything on your boat that could be the cause and keep an eye on the location(s) you see this issue. There also has been “notice to mariners” in the past about TV amps on boats, causing GPS issues. You can always bring up your GPS status screen and check the signal levels and DOP of your GPS receiver. You might want to monitor it and see if you see your DOP suddenly increase. Normally you want your DOP to be around 1 to 1.5 . The lower DOP number, the better. You might speak with some of your fellow boaters at your dock to see if they have noticed any GPS issues in the area. It is important your GPS is placed away from transmitting or noise sources. For example you do not want your GPS within your radar transmission beam.
Thanks for the quick reply. This is a first for this equipment. Never had the issue before last week. Same boat, same equipment, same marina for the last year. Unfortunately, there is little opportunity to compare notes with other boaters. I keep my boat in a high and dry and don't run into many folks when I use the boat. If it happens again, I'll check on the receiver details and inquire about recent changes in WIFI etc in the immediate area. My neighbor is a local tugboat captain. I'll ask him as well.
As you know Baltimore is a busy port and there have been a bunch of Men in Black boats running around the harbor lately. There were some consistent but intermittent anomalies a couple years ago a few miles from where this occurred.
I have a MFD8 with the same problem, I notice when I loose GPS signal it will go all over the place.
Thanks, KT. This has not happened again. My boat is in the high and dry for the winter so no chance to play until spring. All the numbers were good last time I checked so the gps was working.
What's going on
:respect I MFD8 and you also have the same problem, I hope you can give me as soon as possible means.
If you have your tracking set to “TIME” instead of distance; the tracking will not normally show the GPS drift. Small amounts of GPS drift are normal. If you have large GPS jumps in location, the problem is normally related to on boat transmissions from other sources, or local area transmission. If your problem occurs regardless of location, you should contact a dealer to help you locate the source of the on boat interference or evaluate the GPS unit. If you think the problem is related to your GPS unit then you could have the unit checked. If your GPS is Furuno, you can send the unit in for full testing/evaluation to our factory service center. RF Interference is the most common cause of this issue.