I didn't have a fishfinder all last season from my canoe. To find potential deep areas I keep it simple
1 - Look around the shoreline for any very steep banks. If they are that steep then generally the continue down into the water like that.
2 - Points. A tapering point is textbook. Fish all around the point from deep to shallow.
After that I tackle it using the Top/Middle/Bottom technique.
Top - Spinnerbait generally. Jerkbait works well too. Trying to get the aggressive ones to come up and strike.
Middle - Drop shot. Trying to hit the lethargic suspended ones.
Bottom - It's a slow process but I use a 1/2oz Football jig dragged along the bottom. When I feel something I pause, hop, twitch it until I get bit.
Notice how my presentation slows as I go deeper. If that isn't successful move on to the next spot.
Good luck!