By using sonar to spot fish depth, then using pre-determined lure setups, you can put your bait right in front of the fish.
Photo by Dan Armitage
One problem with trolling is not knowing how deep your baits are actually running. Say you have marked fish on your sonar that are holding at 15 feet. You could troll back and forth over them, adding weights and trying different lures and presentations until you get a strike. Or, you could snap on a lure that you know runs 12-15 feet deep when trolled at 3 mph on 100 feet of 10-pound-test monofilament. You can do it.
Determining Precision Depth
Take a few hours out of your fishing time, move to a gently sloping, obstruction-free beach area and experiment. Keep a note and pad handy and select a half dozen of your favorite lures.
1. Put out 100 feet (or a consistent amount) of line, measured and/or marked one of three ways: use a line counter reel, count the passes of the line across a baitcasting reel’s spool or mark your line with a felt-tip pen.
2. Set your trolling speed, which is normally as slow as your motor will operate in forward gear without stalling.
3. Start trolling over water you know to be too deep for your lure to hit bottom. Go back and forth parallel to the shore, move closer and more shallow with each pass until the lure bumps. In your notebook, note the boat speed, water depth and the lure used.
4. Pick out another lure and go through the same process. Try deep-, medium- and shallow-runners, so that you have a lure or two that will run at every depth from 5 to 20 feet deep (or more, depending on how deep fish will hold in your local waters).
Once you know what lures run at what depth at a set speed with a set amount of line out, you are ready to troll with precision. When you spot a fish at 10 feet, you can look in your notes to find the lure that ran at 10 feet when you did your testing, put it out on the designated length of line, run the boat at the designated speed – and bingo! You will be putting your offering right in the fish’s face.