Doc: So the second type is the one-off persistent shift. This is when a new breeze is coming on the scene (often showing up as the old breeze dying). This one is most often signaled by some weather signals—be they cloud or temperature change, an out-of-range shift, or the breeze substantially strengthening or softening. If your eyes are open, you notice something weird is going on.

ROB: But you still do the same thing, don’t you? You work out which side and go for it.

Doc: Well, yes that is right, except it only works once. The shift goes through, or the new breeze comes in, and then there are new conditions and new rules. The same side might not work next time.

ROB: Aha! That’s what we had then, one of them so-called “one-off” babies!

Doc: Well, no. It doesn’t sound like it actually. Was there a permanent change in the wind conditions?

ROB: Well, no actually. If I didn’t know better, I would have said the breeze actually flicked back and forth all day, just like an oscillating breeze.

Doc: Yes. That would be it.

ROB: But it wasn’t oscillating. It was persistent. It didn’t come back until after the end of the beat. By definition, that is persistent, isn’t it?

Doc: Persistent and oscillating actually.

ROB: Now you’re getting me confused.

Doc: No, really. The third kind of persistent shift is the too-long phase oscillation. You often get those off the low, flat land, particularly on a cold and grey day like today, when there’s not much heating going on. What it means is the breeze is flicking back and forth over quite a long period, which effectively means persistent shifts each beat, but it can favor one side or the other. Strictly speaking, it’s an oscillating breeze, but because it has such long phases, one side or the other usually pays, and so it looks like your regular garden-variety “hit-one-side” persistent shift.

ROB: So you still hit the sides?

Doc: Yes, but you have to work out very early on what long-term phase the breeze is in—left or right—and head for the corner where you expect the next major shift. “Too-long phase oscillations” are hard to pick out because there are usually small short-phase oscillations hiding the bigger pattern. A good clue is if you start getting confused about what the mean wind direction is, then you should start looking for a bigger, longer-phase pattern.

ROB: So you really need to keep track of your compass numbers.

Doc: That’s the key. Not just the minute-to-minute stuff, but the patterns over half an hour or more. When you come around the bottom mark, you’re not focused on heading out to the same side as last time. You’re looking to see if you are in the long-term lifting or knocking phase, and get on the lifted tack smartly.

ROB: Cool! Now I can go and show up that crew of mine. They think they’re so smart.

Doc: Actually, I had the same talk with them two weeks ago.

ROB: Oh … Damn ... That was why they got so stroppy when I said, “We’re going right. It worked last time.”

Doc: Sounds like the next round’s on you, skipper.