I have a hummingbird piranha 155 on the bow of my boat, paid 65 bucks for it at Walmart it works for what it is...gives water temps, shows fish and bottom structure somewhat and of coarse depth...the 197 DI would be way better than what i got...on the console i have a Lowrance Mark 4HDI gps unit i paid 125 bucks for from BPS.Seems to work ok has down scan and such, gps works good i still havent figured it all out yet...lol