Thursday, April 27, 2006

Sail Towards the Next Shift

It's been a couple of weeks since my last post about Dave Dellenbaugh's lecture on Top Ten Tactical Tips. The last two tips were about sailing the beat, and so is this one. At least the title is. The discussion then went off into some issues related to downwind sailing and current. Not sure if this is what Dave intended or just where the audience's questions led him.

"Sail towards the next shift on a beat." As Dave said, this works in both oscillating and persistent breezes. If it's oscillating you are sailing a lift out to where the next header should be coming from. And if it's persistent you are sailing the header expecting to be headed more and more and then be able to lay the mark in a big lift. Either way you are sailing the shortest course to the windward mark.

So what does it add to have another tip that says, "Sail towards the next shift on a beat"? Beats me. Can any of you clever commenters out there explain why Dave used up one of his ten tips to repeat advice he had already given? Or am I missing something?

Anyway, under this title Dave then meandered off into various other pieces of tactical advice. First was to say that in light air you should go for pressure and in heavier air go for shifts. Having done most of my sailing in light air on lakes I have certainly learned this the hard way. If you can sail in two knots of breeze over there it sure beats sailing in half a knot of breeze over here, irrespective of headers or lifts or even if "over there" is ninety degrees away from the course to the windward mark or fifty yards above the layline.

Dave then pointed out that often a change in wind direction is associated with an increase in velocity. So in sailing towards a shift upwind you are sailing towards a wind with better pressure and better direction. But the reverse is true offwind.

This is where my Laser sailor's eyes start to glaze over. At one level I can sort of grasp intellectually the standard tactical advice about how you want to be sailing on the headed shift downwind. But it's not something I can relate to physically. Given that a Laser can sail extreme angles by the lee - and is often faster sailing a run by the lee - this whole art of sailing the shifts downwind is something I have never bothered to try and understand and probably never will.

Then Dave got into a discussion of sailing a beat where there is land towards one side, and why it usually pays to sail towards the land. The wind off the land may well be oscillating so there will be shifts you can use. Also the way the wind curves off the land is effectively a persistent shift so you can use that too. Hmmm - I guess that is why my strategy of banging the right corner in a NW breeze (when the land is on the left) in the last few weeks of frostbiting has never seemed to work out? Duh.

BOCTAOE. But of course, the closer you get to the land, the lighter the wind might be. So it might be the wrong choice. Ain't sailboat racing grand?

We finished off talking about sailing in current in the simple example where the current is running straight up or down the wind direction. Dave said that upwind if you head towards the side with the most favorable current, then the effect of the current on your apparent wind will mean that you are sailing in better pressure. This works irrespective of whether the current is running up or down the wind. On the other hand, on a run if you head towards the side with the more favorable current you will be sailing in lower apparent wind.

I must admit this one was a new idea for me. If you geeks don't believe it, draw your own vectors - I'm not starting a current/tide/apparent wind geeking out thread. At least not until we've beaten to death the "how do sails work" geekfest. Perhaps in a few months we can tackle the good old "Is there a lee-bow effect" question and other brainteasers.

So there you have it. A bit of a ragbag of different tactical tips under one heading this time. Next tip is also about the beat.

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