Wave Glider robot

Quoting from an article:
"A rising wave lifts the Float, causing the tethered Sub to rise. The articulated wings on the Sub are pressed down and the upward motion of the Sub becomes an up-and-forward motion, in turn pulling the Float forward and off the wave. This causes the Sub to drop, the wings pivot up, and the Sub moves down-and-forward. This process is repeated again and again as long as there is wave motion on the surface. The propulsion using this method is not rapid, but it is reliable."

"In November 2012, a Liquid Robotics' Wave Glider autonomous underwater glider set a Guinness World Record for the "longest distance traveled on the Earth's surface by a robot" by travelling over 14,000 kilometres (9,000 mi) on an autonomous journey of just over one year duration."

http://www.bluebird-electric.net/artificial_intelligence_autonomous_robotics/liquid_robotics_wave_gliders.htm

Can someone help me understand the "directional control" aspect of this kind of boat? I mean how does it manage to go from San Fransisco to Hawaii on it's own?

 

It uses a rudder on the glider section. Note that the tracks selected are not difficult. San Francisco to Hawaii is all down wind.

https://swfsc.noaa.gov/publications/CR/2014/2014Villareal.pdf