I don't plan on casting it. My thought was to tie the sensor to a short length of heavy line and tow it a foot or two behind a kayak. Operating range shouldn't be an issue and if I'm in a blitz, I could pull the sensor in (or add a treble and use a steel leader

).
As a castable fish finder, I think that it's more suitable for freshwater or still water and I don't often find myself in those conditions. The watch display seems like a gimick and wouldn't be as useful to me as the larger screen (same as the Piranha 1 & 2 models).
It seems that this would be easier than mounting a transducer that would shoot through the hull and it would be one less hole to drill.
I'm curious to know if anyone has any feedback on how well the smartcast or the Piranha portables work.
Thanks