I just got a 997 si , when I go over about 10 mph I loose depth. Im shooting a 30 foot roostertail from my transducer when im up to speed say 30+ mph in my 1850 Crestliner Sportfish. I may need some help in the location. I went by the instructions , but hopefully someone can help. Its rough running across the water not knowing how deep your running in. My HB 161 never looses the bottom. Any help would be great.