Friday, February 02, 2007

Anticipating the shift

Watching for wind shifts on mountain lakes is tricky because the relationship to what the wind is doing on land and what it'll do on the water isn't always obvious. Because we're often sailing near the shore, we may only see a change in wind patterns on the water very shortly before they arrive.

Because of the surrounding mountains, hills, and cliffs, some of the wind doesn't reach the water's surface to give us a reliable telltale clue -- but does sometimes reach the top of our high-aspect main -- if not at the same angle it would have reached or sometimes reaches the surface. Wind shears can be tricky.

And, the wind is sometimes channeled in strange, three-dimensional directions by near-shore topography. Last Saturday we were sailing with Zorro on Constellation northnortheastward under spinnaker with a moderate following breeze. As we passed the Elephant, however, suddenly we were hit with a eastnortheast headwind that plastered the chute against the forestay. Then, in a few minutes, we again got a southerly following breeze.

When conditions are stronger, we can get sudden changes in wind direction and partially vertical downdrafts coming from the Elephant. We call these "Elephant Farts". They can be annoying, as when they force us into endless tacks on headers -- or dangerous, if they catch a crew unprepared.


Post a Comment

<< Home