[TG] [TG11] GPS coordinates save incorrectly

[Drifter18]

Sorry if this has been covered elsewhere but I have not been able to find a solution.

When manually entering a GPS coordinate into my Axiom, after hitting save the numbers have changed. The result being quite a difference from the coordinates that I want to what is saved into the system.
The unit has done this since I have brought it and I have not had any luck with the supplier or other experts in solving this issue.

I have updated recently but still have the same issue.

Any help would be greatly appreciated.

[Tom - Raymarine - Moderator]

Hello Drifter18,

It sounds to me as if you have your Axiom set to a GPS datum other than WGS84. In that instance, the system does an automatic conversion between WGS84 and the configured datum. Unless there is a very good reason and you know exactly what the implications are, we strongly recommend you staying with the default of WGS84, since that's the reference datum for all modern charts. The datum setup is in Home > Settings > Units.

If you've got a WGS84 chart (you almost certainly do) and have been given some waypoints referenced to another datum, I would suggest leaving the Axiom in WGS84 and converting the waypoints/marks to WGS84 before entering them. There are a few online calculators to do that sort of thing, if you know what datum to start from.

If the datum is already WGS84 then obviously something else is going on, in which case please give me specific lat/lon examples before and after entry and ideally a video of the operation of entering the mark so that I can see exactly what's happening.

Regards,
Tom

[Drifter18]

Thanks very much Tom, that was the issue and it’s all solved now. 10 months of frustration is now over!

One other query I have is how deep should the sounder/transducer read to? It’s the side scan one that comes with the unit. At the moment I get to about 160m.

[Tom - Raymarine - Moderator]

Each of the channels will give slightly different performance, and there's a difference between the range that you can pick up some form of echo from the bottom (the maximum specified depth on our website) and the depth of water that the sounder will give good fishing echoes in. I usually recommend taking the maximum specified depths and then halving them for actual fishing ranges.

The specified maximum ranges from our website are:
CHIRP Sonar = 274m (900 feet) | DownVisionâ„¢ = 183m (600 feet)
SideVisionâ„¢ = 91m (300 feet) | RealVisionâ„¢ 3D = 91m (300 feet)
so as I say, I usually reckon on people fishing in about half those depths and getting good results.

The maximum depths depend heavily on speed, water quality, bottom surface and sea-state. As far as a sounder is concerned, it's signal-to-noise ratio that matters, so the engine, hull and electrical (charging and ignition systems) noise will all degrade performance even if the bottom echo is strong.

Short answer: with a bit of speed up, losing bottom at 160m on the RV transducer doesn't sound unreasonable, but post some clear photos back if you're concerned so that we can see what you're seeing. There are lots of high-performance options if you're looking for deeper-water performance.

Tom