humminbird 787

I have this unit on a aluminum traverlers sea nymph boat that has pop rivets. I can pick up the bottom while going slow but most of the time it is all over the place.I under stand the rivets are causeing the problem.does anyone have any suggestions? Also for crappie and hybrid fishing ( TROLLING) should I change the preprogrammed settings? thanks for any help you can share

If you will take a picture of the back of the boat and email them to me I will be glad to look at them to see where the best place for mounting the transducer.

My email addres is [email protected] .

Joby
Humminbird