I've been runing the GT51 from an echomap95sv and have been having no issues picking up bait and fish (even at speed) in 50-80m chasing red emp/nannagyi. (image is a little shallower than asking and have since improved the picture by moving the transducer) The GPSMAP should get you even better results again. Interested to see how you go as i was planning to have the exact same setup in my Yaltacraft when i get it in a couple months.