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Weather Software => Other Weather Software => Topic started by: SB on June 13, 2017, 06:44:17 PM
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I wonder if anyone can help.
I am trying to find an easy way to work out the relative wind direction and speed when one knows the ship course and speed and the forecast/actual wind sped and direction, preferably to do this in an excel format. Can anyone help?
Many thanks
SB
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Maybe this will help
http://www.bwsailing.com/cc/calculating-the-true-wind-and-why-it-matters/
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Thanks. This is where I have got to but the formula(s) below do not work when the true wind speed is greater than the ship speed. Can anyone show me what I am doing wrong and how to correct this? Many thanks.
E F G H I J
Ship Speed (kts) Track Wind Direction Wind Speed (kts) Relative Wind Speed Relative Wind Sp
20 130 260 18 174 26
22 168 260 24 #NUM! #NUM!
19 288 260 15 266 4
10 341 260 10 260 0
I=F6+DEGREES(ASIN(H6/E6*SIN(RADIANS(F6-G6+180))))
J=(E6*COS(RADIANS(F6-I6)))+(H6*COS(RADIANS(F6-G6+180)))