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Thread: The Polars Expedition

  1. #1
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    Default The Polars Expedition

    That sounds like a very successful polars expedition!


    (Moved by request from Philpott's "What I Saw" thread.)
    Last edited by BobJ; 05-29-2019 at 11:03 AM. Reason: Move threads.

  2. #2
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    Quote Originally Posted by Gamayun View Post
    That sounds like a very successful polars expedition!
    :-)

  3. #3
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    Jackie, with your experience, you would be a great asset when it comes time to prepare some polars for Silver Alert.

    Ants

  4. #4
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    hahaha My "experience" is that I know all these serious sailors. I look forward to seeing you again Thursday night, Ants. We met at R2AK last year. As I recall, I lured Skip away from you with the promise of an ice cream cone.

  5. #5
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    Quote Originally Posted by Gamayun View Post
    That sounds like a very successful polars expedition!
    Nice, indeed. Now can someone please post an Excel template that can take the data points and produce the Spirograph-like chart typically used to display polars? I'm not very good with graphing functions in Excel, and can't remember where I left my Spirograph set.
    Lee
    s/v Morning Star
    Valiant 32

  6. #6
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    Quote Originally Posted by AZ Sailor View Post
    Nice, indeed. Now can someone please post an Excel template that can take the data points and produce the Spirograph-like chart typically used to display polars? I'm not very good with graphing functions in Excel, and can't remember where I left my Spirograph set.
    hahaha Yes, I misplaced my spirograph set, too. I think it's lost with my gantt charts. hahaha. You sailors know the funniest words.

  7. #7
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    I'm sure there are targets for the Moore 24 and maybe the Cal 2-27. Those for a Valiant 32 might be harder to find. I'll surf around when I get home.

    Polar diagrams (named for what they resemble) are the source for a chart of targets, not vice-versa.

  8. #8
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    Quote Originally Posted by BobJ View Post
    Polar diagrams (named for what they resemble) are the source for a chart of targets, not vice-versa.
    As we continue to publicly plumb the depths of my ignorance, let me see if I'm starting to understand: The polar diagram is produced by a velocity prediction program, giving you the theoretical best speed at a given TWS-AWA combination. Then you go out sailing and fill in the actual data in the blank table to see how close you are to getting the most out of the boat. So far so good?

    I have this for the Valiant 40:

    Name:  _Polar Diagram  - Valiant 40.jpg
Views: 110
Size:  194.0 KB

    and have searched without success for a Valiant 32 polar diagram -- only 65 of the boats were built, and obviously not for racing, so I wouldn't be surprised if no polar diagram has been published.

    But, the 32 was supposed to be a scaled-down version of the 40, with the same long-keel, skeg-hung rudder underbody proportionally adjusted for the shorter LOD. So, second question: if I re-scale the boat speed dimension on the Valiant 40 polar based on the ratio of theoretical hull speed of the 40 versus the 32, might that provide a reasonable approximation of targets for Morning Star?
    Lee
    s/v Morning Star
    Valiant 32

  9. #9
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    I did a quick search for the Moore 24 and found nothing. One was available for Express 27 and I think it was developed by Carl Schumaker.

    I am quite positive Dave Hodges has one for the Moore at his quickest portion of memory.

    It should be fun crowd at RYC on Thursday evening.

    Ants

  10. #10
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    Quote Originally Posted by AZ Sailor View Post
    if I re-scale the boat speed dimension on the Valiant 40 polar based on the ratio of theoretical hull speed of the 40 versus the 32, might that provide a reasonable approximation of targets for Morning Star?
    Maybe? The 32 has LWL of 26', and the 40 has 34'. Using what I think is the formula for theoretical hull speed, of 1.34 x square root of LWL, gives the 32 a hull speed of 6.83 kts, which is 87% of the 40's hull speed of 7.81 kts.

    If I am reading the polar diagram correctly, the 40 should do 7.6 kts on a beam reach in 12 kts of wind. 87% of that is 6.65 kts. In flat water with new sails and everything trimmed right that seems like a target one could shoot for.
    Lee
    s/v Morning Star
    Valiant 32

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