I need some help from someone that has a broader knowledge about these tranducers than I do. I bought the 798 SI for my 10' plastic boat and on the advice from Wayne P. I will be exchanging the transom mounted tranducer for the trolling motor tranducer. I called HB's customer service (Top Notch by the way) and they gave me the part number for the trolling tranducer, so after I hung up with them I went on HB's website and noticed there was a difference in the two tranducers. Here's the description for both of them.

XNT 9 SI 180 TTransducers.Transom Mount Transducer

Compact Dual/Side Imaging. 20/60/86 (2) degree, 200/83/455 kHz with built-in temperature. 20' Cable. More secure, especially at high force of waves. Improved running angle and an optional lock down screw to override the kick up.

XTM 9 SI 180 TTransducers.Trolling Motor Mount Transducer

Dual/Side Imaging, 20/74/84 degree, 200/83/455 kHz with built in temperature. 15' cable. Includes a hose clamp for attaching to trolling motor. (not shown)

What is the difference between the "86 (2) degree" on the transom mount and the "84 degree" on the trolling mount"? Will I be losing any signifcant SI coverage with the trolling mount?

Thanks for help with this in advance.

Also, will the trolling tranducer be capable of showing the speed you are going like the transom tranducer?

The transducer has nothing to do with speed measurement.  Unless you're using a speed wheel, speed will be measured using the GPS.

Also, will the trolling tranducer be capable of showing the speed you are going like the transom tranducer?

The transducer has nothing to do with speed measurement. Unless you're using a speed wheel, speed will be measured using the GPS.

Ah, I think if I would of thought about that a little harder I would of figured that out.   :-[

I have both transducers and I can't tell any difference in performance between the two.

I may have tried to see if there was a difference if I had read those specs. I'll be more attentive when the ice melts.