transducer

Hi all, I have a Terhi Nordic 6020C which I will be using mostly to fish in loch Sunart, a quite deep sea loch on the west coast of Scotland. I have obtained for it a Lowrance Elite 7 ti without transducer. My question is which would be the most appropriate to go for. Trying to understand the...

I'm thinking of buying a Lowrance plotter/fishfinder combo unit and I can't work out what the practical difference is between the two transducers. Lowrance say the 83 is for freshwater and the 50 is for salt, but I also hear that the 83 is better for shallow to medium depth water. I've just...