B&G Deckman - Manual (Page 45)

Chapter 3: Navigation
3.18
that the time interval between steps multiplied by the number of steps
gives a time that is at least what you expect the leg to take. Obviously,
for longer races the time between steps should be greater; trying to see
too many different options at once merely makes things more confusing,
not less so!
Once you have setup your plan choose menu>planning>do isochrones.
You will then see Deckman draw all possible routes, with the optimum
shown in red (heavy black line in Figure 3.6). You can then choose to
view any or all of wind, current and isochrones by clicking on the
following icons on the tool bar.
Show wind—lines point into the wind
Show current
Show isochrones
Show animation— see Animation below
edit GRIBs
setup—returns you to the Setup menu to change variables
Once you have a plan in place menu>planning>optimum details
allows you to view conditions at each time interval during the leg (note
that the time column here shows you both the day of the month and the
time).
Any number of plans can, and should, be tried to see how the optimum
route would change in various different conditions. Then a decision can
be made as to the most likely and a route chosen to match.