ahskip1,
If those vertical lines are only happening when the boat is moving at a fast speed than it is probably due to air getting under the transducer. An inside-the-hull transducer and transducer splitter cable like neilbober posted will most likely help this. Just make sure that you test the mounting location of the XP-9-20 before you start mixing the epoxy, so that you know it will work in that location.