Join Date: Jul 2007
Location: Northport, NY
Thanked 88 Times in 88 Posts
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Re: ambient wind vs true wind
True winds.. Winds are almost always given in true direction by the weather forecasters in all forecasts. This gets to be very important because most of us sail using magnetic heading vs true to sail a course. Since there are only 3 kinds of wind, on the bow, to much or too little, one can always assume while cruising the wind is forward of the beam. So depending on where you sail, a good sailor always take the magnetic variation into account before setting sail and cursing the weather gods. Down here in the Caribbean that can be as much as 18 degrees. Back in the US the average I believe is 8 degrees of north. Read the compass rose on your chart plus annual variation to get the magnetic deviation. Now since the apparent wind angle will move forward of the beam when sailing, adding the two variations will determine how much you need to beat into the wind, take a tacking duel (getting beat to death and partner not happy)or just forget about it all and turn on the motor. The later will get you there fast , anchor down quicker to watch all evenings entertainment of others getting into the anchorage or dock. Plus you will be further along with your favorite adult beverage of choice. Did I mention the Admiral will be happier!
Currently Bequia, Grenadines, St Vincent
Figuring out your point of sail is not all that difficult. You can motor directly into the eye of the wind... apparent wind direction is close enough to true wind direction (let's forget about current set for the time being). Now take a look around... at your surroundings and your boat on the plotter and the heading line ... that should pretty close to the direction of the true wind. If you destination or mark is forward of the beam and more than the lower (more) angle you can sail.... say 40° then you you can fetch the mark without tacking. Heck if you have a sailboat you can figure this out. NOAA weather is good enough to get you gears working and figuring out what you will be facing one you get off the mooring/anchor.
pay attention... someone's life depends on it