Sailing Trick to Calculate Set and Drift! - SlideMoor Blog

Sailing Trick to Calculate Set and Drift!

How many times have you set a heading to a distant turning mark only to find that the closer you get, the further off the rhumb line you are? This trick requires a chart, or full sheet of paper. Draw the rhumb line course to the mark, noting the compass heading. Using the GPS, note the course made good in reference to the compass heading. Take a reading every 10 minutes and you’ll start seeing the actual course made good. You might be pointed at the mark, but your actual course lay line will be different. After taking readings for about 30 minutes, plot your lay line course being careful to note that it’s usually not a straight line. Some call it a parabolic curve, but we don’t need to get that fancy. Once you’ve plotted the lay line to the mark, you can quickly calculate at what point on the lay line to tack. If you’re careful with the plotting, you’ll hit your mark with a single tack!

Jesse Pariseau

Jesse Pariseau

Director of Marketing & Sales at SlideMoor
I have been in the marine business since 1974. I have a BSEE from Northeastern University, specializing in Marine Sciences Instrumentation. I've been an active offshore sailor for most of my adult life having sailed a couple of Whitbread legs and way too many Bermuda races to mention!
Jesse Pariseau

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