if the fish depths your targeting are that 50mt and less range. i would consider
TM165HW 600w high/30o wide beam CHIRP transducer
or
B75H thru hull 600w high narrow beam if you are wanting better bottom defition.
for a few dollars more
consider the B175HW if you want more horsepower to hit those 100m limits. whilst being super sensitive in the shallows