[TG] [TG11] Axiom/RV-100 - Unclear image

[Tom - Raymarine - Moderator]

Hello Ian,

Thanks for the transducer photos and information. I'll look forward to seeing any photos of the sounder image that you can provide, that will tell us a lot about what's going on.

As far as performance at speed goes, what matters is the signal-to-noise ratio (SNR.) A high background noise level can cause problems just as much as air across the face of the transducer, and if noise is the problem then moving the transducer up or down will generally make little improvement (though it can make things worse by adding an aeration problem.)

To understand whether the problem is low signal (air) or high noise, we recommend putting the sounder into all-manual Gain/Intensity/Surface Filter/Range (on DV, SV or chirp fishinder views, not 3D), then gradually increasing speed and seeing what changes in the image. 50% Gain, 15% Intensity and 0% Surface Filter should give good results on your sounder type. If the problem is air, you'll generally see that the clutter low down in the water column, close to the bottom, stays a fairly similar colour as you speed up but that you get increasingly wide gaps in the bottom echo. If, on the other hand, the problem is noise then the bottom echo will stay continuous as you speed up but the clutter in the water column above the bottom will get stronger and darker with increasing speed, until it's nearly the same colour as the bottom profile. It is possible to get both problems at once.

Regards,
Tom