GPS Offsets and Implement Offsets Explained

Due to the amount of calls received this spring regarding guess rows, I thought I’d take this opportunity to explain the proper method of setting up GPS and implement offsets. The first step is 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 of pass 1 to that of pass 2. I recommend using the flags as mentioned, but there are a multitude of other methods which will accomplish the same goal.

4. 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” to the right. This adjustment tells the machine to drive so the GPS receiver is now 3” to the right of the A-B line. This will cause pass 1 (south bound) to move 3” west while pass 2 (north bound) will move 3” east.

5. 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.

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