Wave Heights in Gulf Stream Nomogram
Significant wave heights over the Gulf Stream for wind speed/direction with an 18 hour duration. Red contours trace the wave height. Note that a 20 knot northeast wind can build sea heights in the Gulf Stream to around 12 feet and a 15 knot northeast wind can build sea heights to about 9 feet!
Boaters sometimes complain that the Coastal Waters Forecast underestimates the wave heights, when in fact they actually ventured out into the Gulf Stream when there was a north to northeast wind! Additionally, wave theory predicts that wave heights will occasionally be higher.