Most fish finders on the ski/fish boats are located on the bow next to the bow light, the transducer can be mounted either under the moter or on the transom.
I installed the GPS/Fishfinder in the beverage holder next to the steering wheel on my Q6 Ski/Fish. Figured it would be out of the way when we're not hunting for fish. Plus the GPS is nice to have next to the steering wheel. My transducer is under the motor - a bit to the right.