[TG] [TG11] RV100

[Tom - Raymarine - Moderator]

Hello Ryan,

Good screenshots, thanks, just what I needed to see.
You have no aeration problem, this is not an issue with transducer mounting angle or location on the transom. There are about as few gaps in the sounder image at speed as you'll ever see on any system at those speeds. And you also have a nice low background noise level at speed on all channels except for the Low Chirp. There is a little cross-channel interference (the 'rain') in the Sonar channel, but that's not unexpected when running multiple channels at once like this. The only thing that would give any cause for concern in any of these is the background noise level in the Low Chirp when running at any sort of speed.

This noise level isn't the worst I've seen by any means, but it is bad enough to cause poor image quality even in shallow water at speed (it's bad even in the 14kph view), and as you got deeper and the bottom echo got weaker then it would be increasingly hard to see even the bottom echo, let alone bait or fish.

The noise can be coming from either the engine electrical system or hull/transducer vibration (actual acoustic noise), so the next step is to find out which of these are the case. Electrical interference can be coming from the charging system through power supply cabling, or could be radiated as airbourne noise and picked up on the transducer cabling. You can eliminate the first one by running the sounder temporarily on a completely independent battery, if possible. If the noise level is unchanged then the cause is either radiated electrical noise or vibration. You may be able to test for vibration by either temporarily placing a pad between the TM265 transducer and the transom (something like a sheet of rubber car floor-mat) to see if this reduces the level of clutter in the Low Chirp view at speed (be very careful to make sure that the transducer's still securely mounted and can't work from side to side and stress the mounting screws or come loose), or press something like a boat-hook with a pad on the end against the transducer in order to damp the vibration a bit when running at a bit of speed. Not easy I know, but if you press something against the transducer or isolate it and the background clutter in Low Chirp is much less then you've proven an acoustic noise problem at Low Chirp frequencies. If this were the case, the solution would be to step the transducer off the transom on an anti-vibration mount of some sort. I would suggest speaking with a shipwright to see what he might suggest there, to do the job and also be secure at high speeds.

Please let me know how you go with this. I would like to follow this one to conclusion.

Regards,
Tom