J/30 Class Association Forums J/30 Forum Racing Tools and Techniques VMG -- Problems and reflections

Easy - that was me returning from Cedar Point YC after the 2009 NAs. That is what tidal currents will do for you on Long Island Sound. The speed displayed is the measured speed by the paddle wheel through the water. The speed over ground was much greater due to the ebb tide currents pushing water to the east. Thus the GPS speed over ground increased the speed in the VMG measurement. Notice that the display shows VMGWP - meaning the TackTick was calculating VMG to waypoint using GPS data.

It's not uncommon to get a 2-3 knot tidal current. We planned the departure time to maximize the current push, rather than fight it.