Raymarine Marine GPS System User Manual page 155

RayTech Navigator User's Guide
The Vmc Plot screen (Figure 5-21) displays the Velocity Made good
on Course toward a specific mark or target. Although similar in
concept to Vmg, Vmc is equal-to Vmg only when the bearing to the
mark and wind direction are identical. Vmc is used when you expect
the wind to change between your present position and the target
(primarily in long course racing). In such an instance, it may be a
smarter tactical move to sail toward your target at the fastest possible
speed, even if that heading isn't directly toward the target.
To use the Vmc plot, select the Course and True Wind Direction and
True Wind Speed to be plotted by clicking on the
Tws
Course and Twd are initially derived from instrument input, but the
screen allows you to change these figures to calculate what happens
if the wind or course changes.
5-64
up/down arrows or by entering numbers directly. By default,
Figure 5-21. Vmc Plot Screen
, , and
Course Twd