GPS Consideration

GPS Consideration

GPS is a wonderful tool when your boat does not have reliable instrumentation, or in the case of small boats, no instrumentation. You should observe a very important protocol though if you try measuring your speed when traveling on a body of water. If you are using the GPS speed reading to evaluate the performance of your propeller, remember that GPS measure land speed, not your on-the-water speed.

To correct for speed differences caused by localized water currents, you should always make at least 2 speed runs in opposite directions. After doing this and recording your results, taking the average of the runs will help correct for speed differences caused by wind and or water currents and provide more reliable info about your propeller’s true performance.