Here is a flush mount bracket Lowrance came out with for Lowrance depth finders that I mounted my transducer to my Lowrance TI 7 on,the back of my g3 1648 jon boat as I fish heavy timber sometimes. It gives good enough bottom reading at my top speed of 26 mph,to keep from hitting anything if I run shallow.

https://www.cabelas.com/product/LOWR...6.uts?slotId=0