[TG] [TG11] Odd readings from an ST800 on an ST70

[Tom - Raymarine - Moderator]

Ah yes, that's the bit I meant to include in my last reply, sorry.

In the last 2 cases I've been involved in, we recommended changing from an 'instrument-type' transducer to a tilted-element fishfinder type connected directly to a compatible multifunction display, and using the tilt of the element in the transducer housing to orient the beam forward and away from the keel. For example, one of the boats had an eS98 MFD and the installer changed the instrument P319 transducer to a CPT-S 12-degree tilted, which has the same cutout, and that solved the problem.

What specific part number transducer is it that you have, though? If it's A22112 then that is a tilted-element type you're absolutely right, rotating it so that beam points elsewhere should solve the problem. In that instance you'd want the keel arrow on the transducer cap to be pointing forwards instead of to the keel.
If you have a non-tilted DT800 (e.g. A22165) then rotating it won't help - according to Airmar's acoustic info for that element it's symmetrical/circular - so it would be a case of fitting an A22112 into the same housing, or replacing with a CPT-S, B60 or SS60 if you have a compatible MFD aboard that can connect to one of those transducer types. They're all available in tilted versions.

Regards,
Tom