I have a 997, I have used it on my 18' Lund and my 14' Crestliner.
On plane I don't get a good reading, But I haven't spent any time adjusting
the transducer to see If I could make it better either. I use mine for the SI
and depth finder at slow speeds.
I will tell you that like many others, I am not pleased to say the least with
the slow GPS issues and the way HB has beat around the bush about it.

Daniel