So i installed a humminbird helix 5 on friday night. Put the transducer inside the hull in a silicone bed. Tested sat in the water it would read 5 feet then blink off. Read again blink off. Then it would read 500 feet then 200 then 6? Any suggestions as to why this is happening? Also my speedometer on the ski itself is way off. Reads a lot slower than i am going. The gps seems to be on with the speed at least, i had a friend pacing me on his suv. At over 40 its reading in the 20's. Thanks in advance for any insight on these issues cause i am frustrated as hell!!