Sailboat racing takes some imagination. Windshifts are one of the key things you need to understand to race well. You may have heard this comment after a race, “I just couldn’t get in phase with the shifts.” Usually, there are two kinds of shifts. A persistent shift is one that is often forecast and will happen over the course of several hours. The other is an oscillating shift or a shift back and forth. Most often this oscillating shift happens over a shorter period of time. Being “in phase” with the shift refers to this second type of shift. When you are in phase with the shifts, you are always sailing on the tack that is being lifted with the shift. This is a topic best illustrated by a gif…
In the first frame, the red boat starts out on its course. The dashed line indicates its future position. Then the shift begins. It is a left shift or some people say the wind is backing (going opposite the direction of the clock) which makes it a lift. The at the point where the red boat changes color to green, it has recognized the shift and is able to sail closer to the mark. It is lifted.
But this is an oscillation, so shortly after recognizing and riding the lift, the skipper realizes the lift is shifting back to a header or some would say the wind begins to clock (shifting in the same direction as the clock goes). The skipper tacks at the point the boat turns blue.
Finally, as the wind continues to clock or lift, the boat changes to black and you can see that again, the boat is sailing the lifted tack, closer to the mark.
This concept can be difficult to recognize on the race course. Making it more complicated you could have a persistent shift over the course of the day from say 270 degrees to 170, but have a consistent oscillation back and forth of about 10 or so degrees as it shifts south. One of the best tools to monitor the wind and your progress is your compass. This allows you visualize and do the math. If you aren’t good with those numbers in your head you can practice by setting up scenarios or you can use a tool like the TackingMaster, which takes some of the math out of your head and puts it on your wrist.