I have a 998c on a 2020SE Action Craft with stepped hull. The SI transducer just could not be mounted where it would read at speed and still give a good side image. I ended up buying a 2nd thru hull transducer for speed and stuck the SI on the left corner of the hull above the bottom line - it is out of the water when on plane - and use in for Left Side view only. But then you don't need SI on plane. The combination seems to work. Still don't like the dim, hard to see screen. Guess I'm just used to a Garmin.