I'm having the same problem with my new humminbird I wrote to customer report and they told me that I may have to move my transducer up to 16 inches away from the prop to get out of the prop wash and also to make sure the the transducer is a 1/8 to 1/4 inch below the bottom of the hull and also may need to angle the transducer but no more than 7 dergrees up and make sure there was no electrical interference so instead of going through a fuse block just wire it straight to the battery I havnt done any of this but I'm thinking of doing it this weekend may be it will help you