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How to properly set up GPS and implement offsets

by Jul 17, 2023Guidance & Steering

Due to the amount of calls I receive in the spring regarding guess rows, I wanted to take this opportunity to explain the proper method of setting up GPS and implement offsets. First, you need to determine the correct GPS offset required. This step is important even if the receiver is mounted directly in the center of the tractor.

1. Create a straight A-B line and engage steering. Drive 100 feet or so and place flags at the draw bar.

2. Turn around and engage steering on the same A-B line. Stop while on the A-B line next to the flags you placed on pass 3. Measure the difference between the paths of travel between pass 1 and pass 2. I recommend using the flags as mentioned, but there are a multitude of other methods that will accomplish the same goal.

3. The example above shows a difference of 6” from pass 1 to pass 2. For this difference, we will enter a GPS offset of 3 inches to the right. This adjustment tells the machine to drive so the GPS receiver is now 3 inches to the right of the A-B line. This will cause pass 1 (south bound) to move 3 inches west while pass 2 (north bound) will move 3 inches east.

4. Connect to your implement and again drive as you would when operating the implement (in the ground). Make a return pass to one side or the other of the original A-B line. Once finished with the return pass, get out and measure the gap (or overlap) between pass 1 and pass 2.

As an example, let’s say I am pulling a planter on 30-inch rows. After my second pass, I measure a guess row of 40 inches on the left hand side. This would mean I am 10 inches too wide on the left. To correct this error, I will enter an implement offset of 5 inches to the right. This will move pass 1 (south bound) 5 inches to the east while pass 2 (north bound) will move 5 inches to the west.

Performing the steps above before planting season (or for any other operation) will save time and headache once planting season arrives. Keep in mind that pulling a planter with a row marker down will draft slightly different than with the row marker up. Either way is fine, but be sure to have it in the position in which you’ll be operating before proceeding with the fourth step.