Originally Posted by
jimp
the HB should be hooked up to the cranking batt, this eliminates one source of electrical interference but not all sources. Make sure the HB power wire is not close to the TM power wire as this can cause interference when using the TM. Cross the 2 power wires at 90 degrees if needed, opposite sides of the boat if all possible. You may have the ducer mounted in an area on the transom that gets turbulance from the big motor, I'm thinking that there is a upper speed limit of 8-10mph on DI units before the picture goes fuzzy and inaccurate, but not sure on HB units.