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Driving a J/111 higher to get down to target speed


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In my J/111, last few races, we have been in about 12 knots of breeze, and I find that beating we're above target speed by a good bit, but when I try to come up, the inside tell tails on the J2 all go completely nuts before I get much higher. We have the J2 trimmed mostly flat, a little twist and the inhauler at or a bit inside the handrail. I did calibrate, and it could be an instrument issue, but this RaceQs shows a J/121 higher and slower, and making much better progress. That's a well sailed boat.

What can I try to get the boat higher without stalling the sails?

The start was at 18:21 and the first leg is short. I was a bit early to the line and had to burn off some speed, so we were slow off the line. There were many other boats on the line, not just two (the start line ends are not shown here). We're headed to mark BP.

https://raceqs.com/tv-beta/tv.htm#userId=1160422&divisionId=74669&updatedAt=2021-08-18T23:52:42Z&dt=2021-08-18T18:07:30-04:00..2021-08-18T19:52:42-04:00&boat=Heat Wave&model=Bavaria40&time=1629325268630&focus=Heat Wave&rival=Wings&tab=fleet&view=auto

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  • George Dewey changed the title to Driving a J/111 higher to get down to target speed

I find with my J/88 that with the inhaulers set there any pinching makes the windward telltales lift. Speed can still be great so I ignore the windward ones and concentrate on speed and the leeward telltales. 

All that happens before I start watching (and trying to avoid directing) all the other operations on board till I have pinched too far and the speed starts to drop! 

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Just a few thoughts,

  • target speed. Not sure if yours is updated, but in 12 knots we go for 7.20 @ TWA 38 - not sure what's the VMG is but easy to calculate-
  • things that help pointing #1: infucking. We're probably one degree further inboard than the tuning guide. As long as you can maintain target speed, just go for it. I would say that in flat see we're +10cm inboard of the handrail. See below.
  • things that help pointing #2: more backstay
  • things that help pointing #3: getting the boom up and slightly to windward. Rudder angle at 3-4 degrees leads to better pointing.
  • things that help pointing #4: hiking harder
  • things that help pointing #5: use speed to sail high (ignoring telltales) but as soon as you're below target speed be sure to put the bow down again. You'll find that there's a zone where the boat dies and feels lame, but both speed and pointing is really excellent. Try to find and stay in this zone as often as possible,

That said. I think it's hard to compare to other boats. We find that the J/111 always benefits from being bow down and going for speed first. But in those conditions we have no issues keeping our lane against most boats (except really good upwind boats like X-41 or CS42).

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Thanks guys, I'll try more inhauler, getting the book higher and sailing above where the telltales look "right." We did hike hard and have lots of backstay, and we have the mainsail leech loaded up too. I'll see if I can find that zone @Blur described. 

Oh, we were sailing at about 7.2 knots and about 38 TWA. I think I recall that the target was about 6.6 or so knots. Updated polars?

 

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27 minutes ago, Frogman56 said:

6.6 is too slow for that WL

Yeah as I think back I don't remember exactly what the instruments were reporting for target, it was 6.x something. We were at about 7.2. This polar plot says 6.9 for 12 kts:

https://www.j111class.org/images/documents/J111_ORC_Plot.pdf

And still, the J/121, a faster boat, was sailing higher and slower and they won that night. Plus, that's a very well sailed boat, those guys are on their game. But maybe we were less above target than I thought, but we were above it. 

 

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Ok.

But the key is to not be more than marginally inside the jib, but make sure you have about 3 degrees of weather helm.

And try not to move the helm....just little adjustments to the traveller.

The jib can be sheeted harder than you think; if in doubt add main twist...

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To be able to compare your upwind leg to the polars, your instruments really need to be calibrated well.in

Is your speedo calibrated correctly around the target speed and is it still well calibrated when you are heeled at 25-30 degrees? At my boat the speedo would indicate a speed about 3-4% too high when heeled and not properly calibrated (compared to a flat boat at that same speed)

The target TWA as published in the ORC guide includes leeway.  So if your instruments do not take that into account, it means that to achieve the target TWA of 38,  your instruments should show TWA around 34 degrees.

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Zeezee,

This last bit not correct. The measured wind input (aka apparent wind) includes leeway. B & G eastimates leeway (linear correlation to heel angle)to derive the TW outputs.

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Correct.  If your instruments DO take leeway into account (e.g. BG H5000). But e.g. NKE does not take leeway into account for the TWA value they display.  So in hat case you need to be aware of this.

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15 hours ago, Blur said:

Just a few thoughts,

  • target speed. Not sure if yours is updated, but in 12 knots we go for 7.20 @ TWA 38 - not sure what's the VMG is but easy to calculate-
  • things that help pointing #1: infucking. We're probably one degree further inboard than the tuning guide. As long as you can maintain target speed, just go for it. I would say that in flat see we're +10cm inboard of the handrail. See below.
  • things that help pointing #2: more backstay
  • things that help pointing #3: getting the boom up and slightly to windward. Rudder angle at 3-4 degrees leads to better pointing.
  • things that help pointing #4: hiking harder
  • things that help pointing #5: use speed to sail high (ignoring telltales) but as soon as you're below target speed be sure to put the bow down again. You'll find that there's a zone where the boat dies and feels lame, but both speed and pointing is really excellent. Try to find and stay in this zone as often as possible,

That said. I think it's hard to compare to other boats. We find that the J/111 always benefits from being bow down and going for speed first. But in those conditions we have no issues keeping our lane against most boats (except really good upwind boats like X-41 or CS42).

 

Blur, with our J/88 we are still experimenting with infucker angles and speed with the inbuilt bias that it will help pointing but hinder speed. This despite some evidence to the contrary as we have a recent track where the side accidentally in-hauled farther was quite a bit fast in boat speed and dramatically faster VMG wise ! 

My question has to do with the fact that infucking does result in a rounder shape to the jib with more camber and we really want it to be flatter as you suggest. Is this an issue you deal with or perhaps is it particular to our boat? We have the spreaders marked for standard leech location but should we be sheeting inside them when inhauling? 

Thanks,

Dan 

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Dan,

Maybe think of it like this:

1. The lift/drag ratio of the whole apparatus (sails, foils, AR, overlap, etc) disposes to an optimum apparent wind angle, steady state, smooth water etc, of 22 - 23 degrees in say 12 TWS.

2. At that AWA, and given the multitudinous other inputs, the 'average best' jib sheeting lead angle is say.. 8 degrees.

3. But the absolute determinant of effectiveness is jib twist, which we must reference from upper leech wools.

So : Low in groove (say 24 awa) upper leeside leech wools just stalling. Mid groove, fully streaming.

Suggestion - Use 3 sets of wools separated by about 1 metre vertically in the top 1/3 and all of them just a handspan in from the leech, vertically aligned.

Use that dynamic flow evidence to figure out the go to spreader reference mark(s)

You might be surprised that the Mid leech is close to the same spot across quite a range - 8 - 16 TWS.

So the infucker is just setting up the correct progressive (i.e. increasing twist) to enable the correct half height leech position and in this example, lee side flow just attached in the top 1/4 of the jib leech.

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6 hours ago, Frogman56 said:

OK!

But that is surely available somehow with NKE?

Not that I'm aware off. It would be easy to implement, but it looks like nke is not doing active developments anymore. I wonder when those companies start realizing they are in the software business and need to push out frequent updates to keep up with customer requirements.

In practice it's not a problem as I have expedition publishing the target TWA - leeway on the displays. So that is then the number you can compare the actual TWA to when trying to point for optimal VMG.

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If you do not have a heel angle output, you may need a matrix. Upwind numbers for Farr 40 e.g. (TWS & Leeway)

8/3.0

12/3.4

16/3.7

20/4.1

And 50% of that value at 85% TWA etc...

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On 8/20/2021 at 2:18 PM, danstanford said:

My question has to do with the fact that infucking does result in a rounder shape to the jib with more camber and we really want it to be flatter as you suggest. Is this an issue you deal with or perhaps is it particular to our boat? We have the spreaders marked for standard leech location but should we be sheeting inside them when inhauling? 

 

I think it help to see this as two different things (as a jib trimmer). First sheeting angle, and second sail shape. Naturally, if you're just adjusting the infucker you will get a rounding shape, but as a trimmer you should be able to get the exact same sail shape at 6 degrees sheeting angle as you had with 8 degrees. Many moving parts :D

On the spreader marks, it's a good thing to get the boat lit up according to the tuning guides first and then goi tighter. It took some seasons to get there, but now we are well inboard both on deck and on the spreaders. Again, I think it helps to separate sheeting angle & twist. Sometimes youy're tighter with more twist. Sometimes wider with less twist.

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On the original post, I would't worry about what the J/121 is doing. Very different boat.

If you're really 100% on target (it took us a few seasons to get there) with resonable pointing, you would do very well on most fleets. Best way is to actually measure your tacking angles on the tracks after a training session or, race, to figure out how much you are off. Then figure out how to improve your pointing ability and still be at target speed.

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On 8/20/2021 at 5:33 AM, Frogman56 said:

... if in doubt add main twist...

definitely, try twist or drop the traveller a little.  Not quite comparable, but on our 109 - locking down the mainsail leech in 12 knots upwind will take us below optimum boat speed. I tend to ease the leech and put a little backstay on before anything else - but occasionally will try keeping the main fully locked down and then dropping the traveller a little. If I can get back up to speed by playing with the leech and the backstay then I won't try anything else, so I don't know all the possible permutations here.

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There are two principles:

1. Mid leech high enough to derive 3 degrees of helm, at target heel angle. (In 12 TWS, heel ~ 80% of max)

2. Additional head twist reduces the tip vortex drag and slightly lowers the ce

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