Just purchased a Lowrance 7x and had 83/200 ducer installed according to factory specs. Boat is on trlr. in my drive waiting for launch. When I turn unit on-the depth reads 8.5 ft. The ducer is 2 ft. from the drive and exactly parallel. There is a keel adj. on the unit,but 6ft? Any help for correct reading? Thanks,getting ready for Geneva.