Re: Digest for cc-3436@googlegroups.com - 1 update in 1 topic

[Cesar Vallejos]

Someone told me you can get polars from ChatGPT. Apparently you feed the boat model and the I J P & E dimensions and presto!

I haven't done that (yet).

CJV

Cesar Vallejos
cjval...@gmail.com
917 617 9269 (m)

On Sat, Jun 21, 2025 at 12:01 PM <cc-...@googlegroups.com> wrote:

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• Looking for polars - 1 Update

Looking for polars

Peter Griffin <petejg...@gmail.com>: Jun 21 11:21AM -0400 Hi Looking for polars for the shorter two spreader mast (36XL). Thanks Pete G Kuleana Sent from my iPhone

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[Chuck Scheaffer]

Polars I found in folders.

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[Peter Griffin]

Thank you everyone for the information. This boat is new to me my last boat was a J120. 

I had Kuleana out in a 20 knot breeze. I am having trouble dialing her in. I think I may not be getting enough fore and back stay tension. This boat has a split back stay and no hydraulics. Any recommendations. Rake, prebend etc. Loose gauge settings etc. 

I will say this boat performs well. Excited to get her dialed in.  

   Thanks

      Peter

Sent from my iPhone

On Jun 22, 2025, at 12:54 PM, Chuck Scheaffer <scheaff...@gmail.com> wrote:



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<C&C 36 XL Target Speeds.pdf>

<C-C_34_Plus_Polars_Angles.jpg>

<C&C 34+ VELOCITY PERFORMANCE PREDICTIONS.odt>

<C&C 34+ Polar Plot Chart.ods>

[Francois Rivard]

Just FYI, 

For what it's worth. 

I used the C&C polar graph given by Rob Ball and created the one pager shown with extrapolated best reaching /running / angles-boat speed with VMG PDF that shows on bottom left of the download options on this email. 

I use it every Wednesday night, and with the boat fairly well optimized with good sails / correct sheeting angles / and good mainsail - genoa trimmers, good bottom, etc.  --> The boat absolutely sails to its numbers both for pointing and VMG ( One of my B&G displays shows both VMG to wind and VMC -> VMG to mark).  if you pay attention at the helm both sails fly fine as low as 45-47 degrees true in light winds (That's in mid-high 30 degrees apparent... ) We're hard to beat upwind.  Now we need to get as proficient downwind... 

-Francois

On Sun, Jun 22, 2025 at 11:05 AM Cesar Vallejos <cjval...@gmail.com> wrote:

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[Peter Griffin]

What kind of back stay do you have ? Split? Non hydraulic?

Sent from my iPhone

On Jun 23, 2025, at 12:00 PM, Francois Rivard <jeanfranc...@gmail.com> wrote:



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[Francois Rivard]

Basic split backstay with the car, no hydraulics, and quite effective. 

-François 

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[David Knecht]

Hi Francois- 

1.Can you share your 1 pager?  

2.How do you raise the backstay car when you want to reduce tension

3.  I have struggled with how to set up backstay tension.  With the two turnbuckles on the stern, so there is significant flexibility in how tight the backstay is in a given car position.  How do you decide that tuning?

Thanks- Dave

David Knecht

S/V Aries

1990 C&C 34+

New London, CT

[Francois Rivard]

Hi David, 

1- The one pager is on the very first email on this chain

2- I uncleat my blocks system / and raise the car as in: Push it up... Not sure what you're asking here

3- I had a pro set the base with a loos gauge.  But he's a competitor and I think he set it too loose. :-) The boat did improve after I tightened it a bit. Look for the forestay to swing about a foot in the middle when you push / swing it pretty hard by hand. You'll know it's in the ballpark when you set the adjustment to tight and it becomes -->  pretty tight.  If you tighten it and it's still pretty loose then you know it's too loose. That's ballpark.  Then go sailing in 10-15 knots and look at the forestay sag when going up wind. Excessive sag will be pretty obvious.  Again, looking at about a foot in the middle max delfection. 

That's for low-mid winds.  I'd say 3 to 12 or so knots.  Anything beyond that I'd say is a couple turnbuckles turns per 4 knots tranche. 

-Francois

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[Blair Clark]

Hello Francois 

Do you have deep keep or shoal winged keel like me?

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[David Knecht]

Hi Francois- comments below

On Jun 24, 2025, at 4:19 PM, Francois Rivard <jeanfranc...@gmail.com> wrote:

Hi David, 

1- The one pager is on the very first email on this chain

Got it.   Thanks!

2- I uncleat my blocks system / and raise the car as in: Push it up... Not sure what you're asking here

I remember now the photos you sent (and I forgot about) which clarifies why I asked and you are confused.  For some reason, your upper backstay wires are longer than mine.  When my backstay is "off", the car is well above my reach (I'm 6'3").  So I have to pulse the two wires back and forth to get it to up to neutral.  Then I have a block and tackle to pull it down.  When I tighten to max, it comes down to about the rail behind the wheel.  I am going to look at the photo you sent me compared to my setup and see if something is rigged wrong or if they were just designed differently.  

I remember a related issue that may be a clue.  The guys who used to launch my boat needed to take the backstay off each spring/fall to get  their lift in place.  They always had a really hard time, especially getting it reattached in the spring.  I had to set up a block and tackle to pull the turnbuckle down and we ended up adding some D shackles to give it a bit more wiggle room.  Since then, I have raked the mast more (to the correct rake) and that is not as big a problem.  Still, it seems awfully hard to attach those turnbuckles.

3- I had a pro set the base with a loos gauge.  But he's a competitor and I think he set it too loose. :-) The boat did improve after I tightened it a bit. Look for the forestay to swing about a foot in the middle when you push / swing it pretty hard by hand. You'll know it's in the ballpark when you set the adjustment to tight and it becomes -->  pretty tight.  If you tighten it and it's still pretty loose then you know it's too loose. That's ballpark.  Then go sailing in 10-15 knots and look at the forestay sag when going up wind. Excessive sag will be pretty obvious.  Again, looking at about a foot in the middle max delfection. 

OK- that's about what I do.

Thanks- Dave

That's for low-mid winds.  I'd say 3 to 12 or so knots.  Anything beyond that I'd say is a couple turnbuckles turns per 4 knots tranche. 

-Francois

On Tue, Jun 24, 2025 at 12:20 PM David Knecht <davida...@gmail.com> wrote:

Hi Francois- 

1.Can you share your 1 pager?  

2.How do you raise the backstay car when you want to reduce tension

3.  I have struggled with how to set up backstay tension.  With the two turnbuckles on the stern, so there is significant flexibility in how tight the backstay is in a given car position.  How do you decide that tuning?

Thanks- Dave

David Knecht

S/V Aries

1990 C&C 34+

New London, CT

<pastedGraphic.tiff>

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[Francois Rivard]

Wing keel. I can outpoint sport boats and I match the "Pro" guy on his C&C 99 with the deep keel. 

It's in the setup and your helming. Not gonna lie,  pointing that high means very frequent helm corrections and constant  staring at the water / wind gauge-Windex / telltales on the genoa. Half the battle is catching the small lifts the other guys overlooked. The guys that say I'm pinching are not seeing my VMG gauge, it doesn't lie... 

As they say: its like balancing a broomstick in the palm of your hand. 

On the other hand, it gets in a nice groove at about 50 degrees true / 40 something apparent if you want to relax a bit.  

-François 

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[Blair Clark]

Thanks Francois, Let me know when you would like to come to NS.

I could use the tuning and helming help :)

Stay cool,

Blair

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