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Leverage vs lifts/knocks

Aug 2, 2010
438
J-Boat J/88 Cobourg
Sorry if this is too basic, but I am wrestling with how to fit these together. As I understand it, leverage is only relevant if the wind shifts and is more profound the further from the rhumb line you are. So if I am on the right side of the course and the wind shifts left, I lose height and made good distance to the mark. If I am going right the left shift gives me a lift and even if I am going further right on the course I am losing nothing further than the original amount unless the wind goes further left. If I thought the wind was going further left I should tack and sail into the header to gain leverage/height.

The risks and opportunities of leverage are mitigated by staying in the middle of the course, but if I think a pervasive shift is coming I should try to sail that side of the course unless the pressure looks better on the other side.

Do I have this right?
 
Nov 8, 2010
11,385
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
No. From a racing perspective, leverage is only relative to other boats.

Leverage is horizontal distance between them. The greater the distance, the great gain/loss potential if a shift occurs. The boat nearest the shift gains as function of the shift amount and the distance as shown below.
Lookforchange_Pic1.jpg


Its also why we 'cover' a boat (by tacking to stay in the same breeze) if we do not want to risk a loss due to leverage.
 
Last edited:
Nov 8, 2010
11,385
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
The risks and opportunities of leverage are mitigated by staying in the middle of the course, but if I think a pervasive shift is coming I should try to sail that side of the course unless the pressure looks better on the other side.

Do I have this right?
In the absence of evidence to do anything else, staying in the middle is the best plan. As you note, it leaves your options open, and minimizes risk.

You said 'pervasive', a tern not really used.

A 'permanent' (goes right 10 and stays there) shift just means you reset your median wind angles.

A 'persistent' (keeps going right) shift you sail into, and then tack out when you can make the mark
 

JRacer

.
Aug 9, 2011
1,235
Beneteau 310 Cheney KS (Wichita)
"In light air, avoid the middle" - IIRC Stuart Walker

In a persistent shift, the boat that gets furthest to that side first wins!
 
Aug 2, 2010
438
J-Boat J/88 Cobourg
Thanks for the reasoned responses Guys, I am interpreting the feedback as agreeing with my thinking if not my writing!
In a PERSISTENT shift I shouldn't freak out over the knock since I am gaining leverage. The caveat would be if I was closely leading or following one boat on my side of the course at the expense of considering the whole fleet. Typically with 4 fleets of W_L boats starting before us the middle of the course is pretty clogged up with downwind boats so we tend to the edges anyway. The real trick is correctly predicting the persistent shifts and/or the side with the best pressure.
Do you Guys in later starting fleets use heel angles on boats up the course as your dominant clue for pressure or something else? Obviously we are poking around both sides before the start but it seems pretty dynamic and changeable sometimes.
Thanks again, Dan
 

JRacer

.
Aug 9, 2011
1,235
Beneteau 310 Cheney KS (Wichita)
You are only gaining, or losing, leverage when you separate from another boat (or the fleet). For example, the whole fleet goes to the left side and are all close aboard one another. In that case, no one really has much leverage over another - not much separation. OTOH, say the fleet goes left and one boat goes to the right. The boat that went right (the one taking a flyer) has leverage on the fleet or the fleet has leverage on the "flyer". The amount of leverage is a function of the distance separating the fleet from the "flyer". In that case if the wind shifts to the left, the guy that went right horizons the fleet and the distance on the horizon job is a function of how far apart they are, the leverage.
 
Aug 2, 2010
438
J-Boat J/88 Cobourg
In the absence of evidence to do anything else, staying in the middle is the best plan. As you note, it leaves your options open, and minimizes risk.

You said 'pervasive', a tern not really used.

A 'permanent' (goes right 10 and stays there) shift just means you reset your median wind angles.

A 'persistent' (keeps going right) shift you sail into, and then tack out when you can make the mark
Sorry for dragging this out but I am having a hard time assessing the possibilities here since I am racing in a fleet that does not typically stay to one side or the other but rather fans out both sides seldom going up the middle due to the W-L boats coming back down the course. If I thought the wind was going to go right and continue going right over the course of the race, I would have previously gone left to use the lift....but now I see how I will lose leverage to the boats that go right first.
Which has the most profound effect on the race, taking the lift or seeking the leverage? My instinct says to stay right but tack before the layline to use any continued right shift and not overstand.

Does it make sense that at least I should gain all the leverage I can by starting on the boat end of the line?
Thanks for the input and discussion, it seems like I am gaining knowledge without making so many mistakes.
Dan
 
Nov 8, 2010
11,385
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Sorry for dragging this out but I am having a hard time assessing the possibilities here since I am racing in a fleet that does not typically stay to one side or the other but rather fans out both sides seldom going up the middle due to the W-L boats coming back down the course. If I thought the wind was going to go right and continue going right over the course of the race, I would have previously gone left to use the lift....but now I see how I will lose leverage to the boats that go right first.
Which has the most profound effect on the race, taking the lift or seeking the leverage? My instinct says to stay right but tack before the layline to use any continued right shift and not overstand.

Does it make sense that at least I should gain all the leverage I can by starting on the boat end of the line?
Thanks for the input and discussion, it seems like I am gaining knowledge without making so many mistakes.
Dan
If there is a persistent shift underway, your only goal is to sail into it as soon as you can, and time the tack out so it lifts you to the mark. That takes practice.

If you go the other way, you just get lifted up, but never to the mark. And by the time you tack out, the wind has shifted so much it looks like you are sailing back to the start.

dell1edit.jpg
 
Aug 2, 2010
438
J-Boat J/88 Cobourg
Wow, great help Clay, this points out that the lift I am seeking at the start is going to end up being a header sooner or later as I tack across.
Thanks! Dan
 
Nov 8, 2010
11,385
Beneteau First 36.7 & 260 Minneapolis MN & Bayfield WI
Wow, great help Clay, this points out that the lift I am seeking at the start is going to end up being a header sooner or later as I tack across.
Thanks! Dan
Yep.

The best way to think of this is like this:

SOME portion of this leg has to be sailed on the adverse (knocked and getting worse) tack. The earlier you can do that, the less painful the angle is going to be. Early on, you're down 5. Do it later, and you're down 25.
 

JRacer

.
Aug 9, 2011
1,235
Beneteau 310 Cheney KS (Wichita)
Or, put another way, assume you are sailing to the right on port tack in a persistent right shift i.e. the wind is going to the right and keeps going to the right. You will be sailing in a knock, bow keeps going down as you progress. What is happening is the starboard tack layline is "coming to you". So, if the wind keeps going as expected (doesn't come back left) then eating that knock across the right side of the course, and doing it sooner rather than later, will eventually put you on the starboard tack layline and its time (actually past time if the shift continues) to tack for the mark. That's what Clay was saying regarding it takes experience to know when it's the right time to tack out of the header (persistent shift). Do it too early and you won't make the mark, do it too late and you will overstand.
 
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Oct 26, 2008
4,995
Catalina 320 Barnegat, NJ
I tend to think that I would rather overstand than be shy of the layline. I understand that B is in the best position on this diagram, but I feel better when I know I can make the mark. If a shift goes in the other direction, then the advantage goes back to C. If the shift stays the same, then the boatspeed of C should improve with the lower angle, no? (Maybe it doesn't improve enough). At least C has a better position than D in any case, except when the shift keeps going right.
 
Oct 26, 2008
4,995
Catalina 320 Barnegat, NJ
@Ward H if I still have you as crew, we better pay attention to the shifts, right? Our 6 race series is over, but I'm hoping there will be something else to enter this fall! Did you join the Pursuit race on Saturday?
 

JRacer

.
Aug 9, 2011
1,235
Beneteau 310 Cheney KS (Wichita)
I tend to think that I would rather overstand than be shy of the layline. I understand that B is in the best position on this diagram, but I feel better when I know I can make the mark. If a shift goes in the other direction, then the advantage goes back to C. If the shift stays the same, then the boatspeed of C should improve with the lower angle, no? (Maybe it doesn't improve enough). At least C has a better position than D in any case, except when the shift keeps going right.
All true! But, also keep in mind that if the wind does go back left then both B & C go bow down and that perhaps puts C in the bad air off the back of B's sails so maybe she gets a bigger knock as a result. Also, when they go bow down the boat in the lead and to leeward gains - the geometry - she shows C her stern - that maybe puts B far enough ahead to be able to tack and cross C if necessary to get back right to a layline. Just something else to consider in the mix. If the wind keeps going right in the diagram then B has played it perfectly.
 
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Oct 26, 2008
4,995
Catalina 320 Barnegat, NJ
Yep.

The best way to think of this is like this:

SOME portion of this leg has to be sailed on the adverse (knocked and getting worse) tack. The earlier you can do that, the less painful the angle is going to be. Early on, you're down 5. Do it later, and you're down 25.
Now a comment you made on another thread about somebody sailing into a lift during a race makes sense! This is something I'm going to focus on next opportunity. I think I've always had a tendency to try to sail on a lift as early as possible rather than get to the favored side. This also helps to explain why the compass headings are so important. You can't know the favored side without knowing the headings.
 
May 17, 2004
3,434
Beneteau Oceanis 37 LE Havre de Grace
Now a comment you made on another thread about somebody sailing into a lift during a race makes sense! This is something I'm going to focus on next opportunity. I think I've always had a tendency to try to sail on a lift as early as possible rather than get to the favored side. This also helps to explain why the compass headings are so important. You can't know the favored side without knowing the headings.
Absolutely, especially on Barnegat where the prevailing early afternoon wind is a gradual shift from East to South.
 

JRacer

.
Aug 9, 2011
1,235
Beneteau 310 Cheney KS (Wichita)
Absolutely, especially on Barnegat where the prevailing early afternoon wind is a gradual shift from East to South.
If your pre-race analysis of the upcoming wind conditions or your local knowledge of a tendency, such as David mentioned, indicate that a shift (persistent) will occur in one direction or the other, you are free to play the oscillating breeze during the race but be sure that you "protect" the side of the course that will have the expected shift. In the East to South example stated, you can play the shifts, tacking on the headers going up the course but you would want to protect the right side. That is, be the boat or one of the boats closest to the right side while playing the oscillating breeze. That gives you the best position relative to the fleet when that persistent shift occurs and lets you beat feet in that direction and be the first to get to that side. Timing of the expected shift of course impacts how soon you want/need to be on that side of the course.
 

Ward H

.
Nov 7, 2011
3,096
Catalina 30 Mk II Barnegat, NJ
@Scott T-Bird The last club race is a challenge race with another club at the end of September.
We’ll go over this before then.
Missed last Saturday ‘s race, was on our boat with a Cathy.
 
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Aug 2, 2010
438
J-Boat J/88 Cobourg
Just saw a real application of the lift/knock vs leverage. Leading boat rounds the leeward mark and anticipates a left shift so they tack around the mark to go left and build leverage until the second place boat rounds the mark. Tacking back to port then insures the lead boat shares the lift with no risk of losing leverage and having gained some leverage.
Sounds like a lot of thinking at a time with lots going on but that is why it is good to puzzle it out now for me.
 
Aug 2, 2010
438
J-Boat J/88 Cobourg
Interesting how this played out today/yesterday in the AC. In leg 5 Luna Rossa tacked left to cover forcing the Kiwi's to split into a knocked beat but the wind continued to shift right and the Kiwi's gained a huge amount of race course due to the leverage. It was a risk vs reward situation but the Kiwi's who benefitted didn't really take a conscious risk they just had to respond to the actions of the other team who were limiting their own risk by covering.