I new we could get a good sensable anwser out of you. It was hard, but I new it could happen. The only thing wrong with that last answer would be if the 788 has an internal gps, this could throw the ole boy off by 20 ft or so because his ducer would be 16ft behind his gps and with the 2'-4' leadway of the gps this would equal 18'-20' off. He would be fishing by a bouy marker he threw out that just barley is within sight of the structure he thought he was fishing. So with all this being said, this answer you provided really is just poo too. Now this aint an argument and I aint disputing you and your wealth of knowledge. Course if it has an external gps puck then refer to WB's last answer. His WOULD NOT be poo, if you mount your puck close to your ducer.