Passing by Storms, and Vice Versa

Whether sailing 'virtually' or in real life, storms that pass by can help or can hurt.

In real life, avoiding a potentially dangerous storm usually takes precedence over trying to take advantage of the storm. 

In virtual sailing, the dangers are virtual as well.  With 'real' dangers gone, it is easier to analyze how to use a storm to improve sailing speed.

As I write this, the Vendée Globe sailors [real and virtual] are moving across the Indian Ocean towards the waters to the south of Australia and New Zealand.  The storm pattern looks like this:

 It doesn't take a great deal of analysis to determine that:

• Storms rotate clockwise in the southern hemisphere.
  
• Sailors heading west will do best by bouncing across the top [that is across the northern part] of the storm's wind rotation.

Of course, a sailor's life is never quite that simple.

• Great Circle routing looks at the shortest distances between two points on the globe, and not on a flat map. The meridians [lines of longitude] are much closer together near the poles than they are near the equator.  For example: 10 degrees of longitude is:
   -- 459nm at 40*S latitude
   -- 383nm at 50*S
   -- 298nm at 60*S
  These are differences that a racer must take into account.
  
• The Vendée Globe race committee has established 'ice-gates' to keep the racers from sailing too far south -- and either hitting ice-bergs or freezing to death.

What is the best overall strategy?
That is the topic for the next blog entry.