I am trying where to mount the side scan transducer for a new Humminbird 898i C. Those of you who have mounted one of these things, did you transom mount the transducer or trolling motor mount it, and why? I'm sorta leaning toward the trolling motor.

It really depends on personal preferance.  I like it on the jack plate for a few reasons, one its above the bottom of the keel and is protected, and second it allows me to view the area I'm fishing before I decide on that location.  Also with the use of bouys I can motor around and mark the ledges.  Then on the TM I use normal HDS sonar to see where I'm at it relation.  Also, you can get the two linked and still use the si.  Overall the side and down scan is always being used in the back, while if on the tm you only get it when its down.  Just my two cents.  Other things to note, don't have both sonars going at the same time they may interfere with each other.

I have both and prefer the trolling motor position, BUT------

A suggestion: if you haven't used that technology before, mount the transducer on the transom so you will have a steady image to learn from.

After you get familiar with how it works, then you will realize its benefits on the trolling motor.

On the trolling motor, the images will be distorted if you are not aware of how the images are displayed and why.

I know some guys that have had Side Imaging for more than 2 years and they still don't get it because they haven't made the effort to learn it.

I mounted mine on the step where the drain plug, intake for the live well, etc., are located.

I mounted it to the right.  The problem, which I managed to solve was that if you hit a submerged object, when the unit tripped, the trailing edge of the transducer would hit the bottom of the hull.

The solution was to remove the two star washers, that lock the transducer in place on the mount with two neoprene rubber washers.

The trick was to get the assembly tight enough so that it would stay in its position at any speed, but if it hit something that made it trip, the transducer could "unfold" and slip out of the way.

The transducer and the bracket which trips roughly form a right angle.  Now, when the bracket trips the angle of the transducer and bracket can open up, allowing the entire transducer to slip up behind the step.

The advantage of this is that the transducer will record the bottom at speeds over 40 mph.  At 50 or higher, the image gets iffy, due I suspect to air being carried under the bottom of the hull, and interfering with the transmission of the signal and reception of the echo.

I couldn't mount it on the stern because the motor has no jack plate and would interfere with the left side imaging.

It took a bit of trial and error, getting the height just right, because of the deadrise of the hull, to get a good image at speed.

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This photo was taken before the transducer was mounted.  It is mounted on the same surface as the drains and intakes, in the area that is behind the transom saver.

I am always running into rocks and logs with my trolling motor so that transducer gets knocked around pretty good.  I mounted my si on the jackplate.  its protected there.

Here is the HDSI transducer on a Motor Guide Tour trolling motor with the Transducer Shield and Saver bracket.