[TG] [TG11] Marking Fish in Deeper water

[Tom - Raymarine - Moderator]

Hello Solidnetworks,

I wouldn't say that the RV system could mark fish in 300m - I'd say that that was about the upper limit for marking the bottom, but it's unlikely to show anything much smaller than a large, dense bait school deeper than 150m or so. Generally I recommend RV for use in up to around 100m of water. People do certainly use it deeper with good results, but that's dependent on water conditions, the noise environment of the boat (electrical background noise, hull vibration etc.) and the user's expectations so I prefer to err on the side of caution.

I would definitely stay on Auto for all of the Sensitivity settings - only the most experienced charter skippers, on the water 200+ days a year can generally out-perform Auto - but I would use Auto+50% Gain when in deep water, and offset this with an Auto-minus (say Auto-20%) Contrast/Intensity/Colour Gain so that the image isn't too over-saturated and simply red/blue (if it is, you lose valuable information about the strength of the return which can help separate a school of bait from a single predator.)
One exception to the all-Auto rule is if you're looking for surface fish, e.g Mahi mahi around the FAD. In that case it would be a good idea to use 0% Surface Filter/Noise Filter (TVG), because non-zero Surface Filter can reduce the intensity of near-surface echoes.

If you'd like to take some photos or better, screenshots (via the Power menu) next time you're out, I may be able to say more. If taking photos, please make they're high-resolution, in-focus and include the whole screen rather than just a part.

Regards,
Tom