I just bought a boat that did not come with a depth finder. I bought a depth finder/fish finder and am in the process of installing the unit. In reference to mounting the transducer I installed it in the back of the boat clear of the lower unit and where the transducer would be in smooth running water. The manual calls for the transducer to be mounted at least one foot away from the lower unit but the trailer racks are inhibiting me from doing that. The Depth/fish finder works good so far. The only thing I see is some disturbance on the finder once I accelerate on the boat, once I get to cruising its fine.

With the trailer racks on either side of the lower unit, is there anywhere else to mount this thing?

Sound like you did good.

The instructions for those things should probably have a line added that says, do all these things unless there are obstructions (like the trailer), then they would be more resonable.

As long as you have it in a location that stays in clean water when you are on a plane (it is not mounted so far away from the centerline that you are lifting it out of the water), and you are not rubbing it with your motor then all should be well.

The interference that you get on startup is more than likly bubbles coming under the hull, and since it goes away on plane, I would not worry about it.