__To Solve Composite Sailings:__

**Don't:** Do not just draw your straight line on a gnomonic chart and sail the limiting latitude once you
reach it. This route will be much longer, and thus more costly than sailing as follows.

**Graphically:**

-First, find the appropriate Gnomonic chart for your ocean region

-Gnomonic charts are used because GC curves are represented as straight lines

-Second, find your limiting latitude

-If you know where an ice flow or land will be, plot it on the chart so that you know to avoid it.

-From your point of departure, draw a line that will be tangent (touching at only one point) to your limiting latitude
toward your point of arrival.

-This line will be the most efficient way to reach your limiting latitude, while still approaching your destination

-From your point of arrival, draw line that will be tangent to the limiting latitude

-Between the two points where your lines meet the limiting latitude, you will sail along the limiting latitude (this
will be a Parallel Sailing)

**Mathematically:**

-Use the equations at right to solve for your point of tangency; this will be the point at which
your GC track become a Parallel one.

-These equations can also be found on Bowditch page 350

-First, convert all of your positions into degrees and tenths rather than degrees and minutes

-As you know your limiting latitude already, solve for DLovx using one of the equations provided

-Either add or subtract DLovx to or from your initial or final longitude to find the longitude of
each of your points of tangency

-From here, use GC and Parallel equations to find course and distance information between the points.