How to Use the VMG to Wind tables
How to use this chart
Fast Boats and Missing PointsIf you have a very fast boat this chart may not work for you. For example, if you can sail faster than the true wind you probably have more instruments than just a masthead fly so use that. The limitation on this plot is that this is not what they call a single valued function. In English that means that for any apparent wind angle there are two boat speeds that can produce the same VMG to Wind. I am only plotting the first one. As the boat speed gets higher and higher, the VMG actually falls. My suggestion of plotting such points at the maximum is based on the probability that these are off your target apparent wind angle and that the function if fairly flat there anyway meaning the boat speed changes a lot before you actually do decrease the VMG to Wind.
You may also find that you are sailing at a speed that is not on the chart for the wind angle you are sailing. For example, you might be going 7.5 knots at 40 degrees apparent but the numbers for the 40 column stop at 7.2. Don't plot that point below the 7.2 number, just plot it at the last number, 7.2 in this case. It would actually be more correct to plot it higher on the column because as discussed above, this is not a single valued function and in this case sailing fast means you are sailing so far off the heading to the mark that your VMG has actually gone down. But as I said above, it is unlikely that these points are near your target boat speed to it just should not matter.
If you find this handy tool not so handy, just use conventional graph paper and plot the VMG from the Calculator for various apparent or true wind angles and find the optimum that way. You can also use the calculator to find the VMG for the missing points and continue to use this paper for most of your points.
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