Get you a mounting plate for that Ducer. The SI is squirelly and those that want to tweak it rarely get by without tweaking and adjusting on it.

Amazon.com: Rig Rite Manufacturing 920 Marine 3.5"x 12" Horizontal Transducer Plate: Automotive

Or, I saw a cool mount over the the Main board the other day. Dude made a bracket to attach to the jackplate. Sweet. I'll see if I can find the link for ya.

Wannabe...