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Re: [Michalak] Re: Leeway

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  • tom s
    Anders, I think you got it all right except for one detail. I believe you need to use the sin of the angle. the exception to this would be tacking through 90
    Message 1 of 88 , Mar 18 1:42 PM
      Anders,

      I think you got it all right except for one detail. I believe you need to use the sin of the angle. the exception to this would be tacking through 90 degrees, in which case the sin and cosine are identical (because your angle made good would be 45 degrees)

      Tom

      Sent from my iPad

      On Mar 18, 2013, at 1:02 PM, Anders Bjorklund <andersbjorklund5@...> wrote:

      > If we let "A" = the angle between your track over the ground and the true
      > wind, "VMG" = your velocity made good to windward, and "V" your velocity
      > over the ground, then:
      >
      > V = VMG / (cosine A)
      >
      > Your speed over the ground would be the VMG to windward, divided by the
      > cosine of the angle of your track to the true wind.
      >
      > The values of the variables are all changing with time, so the equation
      > strictly holds only for each moment in time. But to the extent that average
      > values are meaningful, if you know how long it took you to gain a certain
      > distance to windward (even if it was all on one tack), and you know the
      > relatively constant angle of your track to the wind, it will give you your
      > average speed over the ground during that time interval.
      >
      > Still able (barely) to remember some math,
      > Anders
      >
      > On Mon, Mar 18, 2013 at 12:15 PM, CHARLES <chuckpierce@...> wrote:
      >
      > > So how would you turn that around to be used to calculate track speed (as
      > > opposed to windward speed) over the ground from the angle off the off the
      > > wind and the windward speed?
      > >
      > > I can do A2xB2=C2 on a right angle with 2 equal sides and come up with
      > > about 8.4 miles sailed up the 6 mile channel which puts track speed at
      > > about 3.4 knots given the time it took to sail that distance. That would
      > > only really apply if every tack were equal in distance which they were not,
      > > but it might be close, anyway.
      > >
      >
      > [Non-text portions of this message have been removed]
      >
      >


      [Non-text portions of this message have been removed]
    • John Trussell
      A small cooler with ice and drinks, an empty porta potti, and a canister with flares. _____ From: Michalak@yahoogroups.com [mailto:Michalak@yahoogroups.com] On
      Message 88 of 88 , Mar 21 4:38 AM
        A small cooler with ice and drinks, an empty porta potti, and a canister
        with flares.



        _____

        From: Michalak@yahoogroups.com [mailto:Michalak@yahoogroups.com] On Behalf
        Of graeme
        Sent: Thursday, March 21, 2013 3:32 AM
        To: Michalak@yahoogroups.com
        Subject: [Michalak] Toon19 ? (Re: Back In The Day...)







        John, just to clarrify, is there anything else much in the boat with you in
        that photo?

        Graeme

        --- In Michalak@yahoogroups.com <mailto:Michalak%40yahoogroups.com> , "John
        Trussell" <jtrussell2@...> wrote:

        > The pictures of Toon 19 were taken with a 10 lb anchor and ten ft of chain
        in a compartment under the fore deck. Trimming ballast is always an option.
        > John





        [Non-text portions of this message have been removed]
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