How to tell when a header isn't just an oscillation?

[DrJudyB]

trying to improve my tactics and this one is a question I struggle with. If I tack immediately and the shift is short then I have lost ground but if I wait too long then I have lost that way too. Do you try and track the shifts before the start to determine if it is shifty or steady and try to use that as a guide to jumping quickly to tack on the headers?
To be fair, we are often in pretty close quarters and I seem to end up closer to the pin avoiding the log jam so tacking is often out of the question but I would love your thoughts.
Dan

I'm not an accomplished racer nor tactician, but here is a system I was taught years ago. I hope I remember it correctly. If not, I'm sure somebody will correct me.
One thing I am 99% confident that I remember correctly is that you need to know what the median TWA is. That's the metric you use to decide if it's time to tack.

Before the race, record wind direction oscillations over a couple of cycles.Sail slowly upwind. Every 60 seconds turn head to wind and record the heading when the boom is on centerline. After a couple of cycles or recording, determine what the median wind direction is. Also, figure out how long each oscillation lasts, and then look to see if there is any long term trend in wind direction.

During the race:
1. When you have been sailing on a lift, and then the wind starts to shift back, wait until the TWA crosses the median. Until it crosses the median, you are being lifted compared to the median.
2. When the TW crosses the median, tack. While the wind is in the first half of the cycle and now lifting you, foot and to fast. Sail a few degrees lower, so you're fast. This will maximize your VMG upwind relative to the median TWA.
3. As the cycle starts to swing back and you start being headed, pinch a little even if you slow down a little. This will also maximize VMG upwind towards the median TWA.
4. Tack when the wind crosses the median TWA.

And also, remember you need to distinguish between a wind direction header and a velocity header. When the wind speed drops, the apparent wind moves aft and heads you. But don't fall off when you get a velocity header. Your boat has stored kinetic energy that you can use to "coast upwind" until the boat slows to target speed. After you slow to your target speed for the weaker wind, then fall off to the correct angle. In fact, you can steer and coast straight up into the wind for a second or two until the boat slows to its new, slower target speed.

Judy

(PS, if there is a long term windshift, you will need to change the "median" angle over time to reflect the long term trend, but that's too fancy for my brain to handle. Somebody has to pay attention to the compass while you're tacking and record the angle that the boom is on centerline, or else you need some sohpisticated instruments)

 

[Ross S]

I was actually IN this race at Bayfield Race Week, on another boat another fleet. This is what happens when a driver does not knot the rules down pat and tries to rely on others for 'help'.

I'm not a racer and not all that familiar with race rules. I'd love an explanation of what I'm watching here!

 

[JRacer]

I'm not a racer and not all that familiar with race rules. I'd love an explanation of what I'm watching here!

You are seeing a guy overtaking from astern and attempting to exercise rights which he does not possess. As the overtaking boat from astern, he has no right to bring that boat up..

 

[danstanford]

So who won the race?

Same boat who always wins! They are two experienced racers who have been racing here for years and their tactics are almost always great. We used to struggle with them but now with our new racier North jib we are right there with them, especially in stronger winds.
They are in our sights tho....

 

[danstanford]

On reflection, I would like to answer my own question. Given that I think we were a little faster upwind, and that we were going to have to spend some time on starboard to get to the mark, I should have tacked into clear air and then tried to roll over the top of him closer to the windward mark. Though my actual strategy got me into clear air, the footing caused me to lose height to the mark and I spent a lot of time in his shadow. I think a short starboard tack could still have kept me on the right side but would have reversed the roles.
Anybody disagree?

 

[Ross S]

You are seeing a guy overtaking from astern and attempting to exercise rights which he does not possess. As the overtaking boat from astern, he has no right to bring that boat up..

Thanks!

 

[Jackdaw]

I'm not a racer and not all that familiar with race rules. I'd love an explanation of what I'm watching here!

Here some details, with rules
0:24 BIG stops luffing and begins a starboard approach on the RC boat's layline
0:38 SMALL tacks to starboard to windward and in front of BIG and is now ROW being clear ahead (RRS 12)
0:45 SMALL turn bow down to get on the same line as BIG. While doing so she creates overlap (RRS 11) and now BIG has immediate ROW (RSS 15). BIG calls 'take her up', meaning she wants enforce her leeward rights.
0:50 SMALL turns up and appears to break overlap. This is where it gets interesting.

Did she actually break overlap? If no she never got rights back
If she did, did she leave enough time/room for BIG to react? (RSS 15)

Most would answer yes to both questions. So now BIG has to think quick.

0:55 BIG driver panics. He starts calling to his leeward boat, who is overlapped and has right on him (RSS 11). Leeward boat does not move, nor needed to.

0:57 BIG needs to slow down (luff) or tack and take a 2nd row start, but needs to one of these things NOW. Instead, he makes matters worse by first turning down (building speed), before coming back up and catching SMALLS backstay.

Both boats protest. Local PC tosses SMALL. Appeal to US SAILING national appeals tosses BIG for failure to keep clear.

 

[Jackdaw]

I'm not an accomplished racer nor tactician, but here is a system I was taught years ago. I hope I remember it correctly. If not, I'm sure somebody will correct me.
One thing I am 99% confident that I remember correctly is that you need to know what the median TWA is. That's the metric you use to decide if it's time to tack.

Before the race, record wind direction oscillations over a couple of cycles.Sail slowly upwind. Every 60 seconds turn head to wind and record the heading when the boom is on centerline. After a couple of cycles or recording, determine what the median wind direction is. Also, figure out how long each oscillation lasts, and then look to see if there is any long term trend in wind direction.

During the race:
1. When you have been sailing on a lift, and then the wind starts to shift back, wait until the TWA crosses the median. Until it crosses the median, you are being lifted compared to the median.
2. When the TW crosses the median, tack. While the wind is in the first half of the cycle and now lifting you, foot and to fast. Sail a few degrees lower, so you're fast. This will maximize your VMG upwind relative to the median TWA.
3. As the cycle starts to swing back and you start being headed, pinch a little even if you slow down a little. This will also maximize VMG upwind towards the median TWA.
4. Tack when the wind crosses the median TWA.

And also, remember you need to distinguish between a wind direction header and a velocity header. When the wind speed drops, the apparent wind moves aft and heads you. But don't fall off when you get a velocity header. Your boat has stored kinetic energy that you can use to "coast upwind" until the boat slows to target speed. After you slow to your target speed for the weaker wind, then fall off to the correct angle. In fact, you can steer and coast straight up into the wind for a second or two until the boat slows to its new, slower target speed.

Judy

(PS, if there is a long term windshift, you will need to change the "median" angle over time to reflect the long term trend, but that's too fancy for my brain to handle. Somebody has to pay attention to the compass while you're tacking and record the angle that the boom is on centerline, or else you need some sohpisticated instruments)

This is absolutely correct, with one change.

TWA (True Wind Angle) is the angle that the boat intercepts the wind, RELATIVE to the boat's heading. So for most boats upwind this will always be about 45 degrees. TWD (True Wind Direction) is the absolute angle the wind is coming from and is what you ideally track.

The trick is that 99% of boats cannot. It requires well calibrated wind instruments, interfaced to your boatspeed and compass.

So most get by with recording their CLOSE HAULED heading angle on both boards. Going upwind on starboard and watching the compass move from 305 to 325 would probably give a mean of 315. tacking onto port would probably show a range of 35 to 55, with a mean of 45.

Now you have your angles, using just a compass.

 

[Ross S]

Here some details, with rules
0:24 BIG stops luffing and begins a starboard approach on the RC boat's layline
0:38 SMALL tacks to starboard to windward and in front of BIG and is now ROW being clear ahead (RRS 12)
0:45 SMALL turn bow down to get on the same line as BIG. While doing so she creates overlap (RRS 11) and now BIG has immediate ROW (RSS 15). BIG calls 'take her up', meaning she wants enforce her leeward rights.
0:50 SMALL turns up and appears to break overlap. This is where it gets interesting.

Did she actually break overlap? If no she never got rights back
If she did, did she leave enough time/room for BIG to react? (RSS 15)

Most would answer yes to both questions. So now BIG has to think quick.

0:55 BIG driver panics. He starts calling to his leeward boat, who is overlapped and has right on him (RSS 11). Leeward boat does not move, nor needed to.

0:57 BIG needs to slow down (luff) or tack and take a 2nd row start, but needs to one of these things NOW. Instead, he makes matters worse by first turning down (building speed), before coming back up and catching SMALLS backstay.

Both boats protest. Local PC tosses SMALL. Appeal to US SAILING national appeals tosses BIG for failure to keep clear.

Very detailed response! Thank you so much for taking the time to explain, I appreciate the opportunity to learn.