hi, recently i purchased the humminbird 778C fish finder,thinking that this unit would be able to not only see the fish but be able to see them changing there minds..the head unit seems alright, but man have i had some hassles with the supplied transducer..it was fitted by a marine shop and wouldnt read the depth while planning ,say 25 knots..ive re-positioned it after reading forums and youtube advice. tested it on the water had it back and fourth from the trailer to the water while i did adjustments and yet it still doesnt read on the plane..really regretting buying this unit.is there a fix...or am i able to buy a transducer that compliments the 778c unit..?.