[Rhodes22-list] Compasses

[Bob Weber]

Slim, now do the same on the boat and you got it SWUNG.  Bob

>From: Steve Alm <salm at mn.rr.com>
>Reply-To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
>To: Rhodes <rhodes22-list at rhodes22.org>
>Subject: Re: [Rhodes22-list] Compasses
>Date: Fri, 08 Apr 2005 15:44:10 -0500
>
>Step one checks out.  I took a full sheet of newspaper and creased it in
>half both ways and diagonally and drew lines with a straight edge.  Since 
>my
>compass is still mounted on the splash board, it's an easy and sure way to
>line the board up on the lines on the paper.  I laid the newspaper out on 
>my
>wooden dining room table and went to work on the adjustments. After about 
>35
>minutes of fiddling, I got it to be consistent on all lines (8 positions) 
>to
>within a half of a degree.  Then I repeated the test in other rooms of the
>house and basement and out on the front walk.  Results were consistent, so
>my compass is working.  However, I always thought my house and the street 
>in
>front ran exactly north and south but the compass is saying it's a few
>degrees off.  And maybe the street isn't exactly north and south but I 
>don't
>have a second compass to cross reference.  I have a couple small hand-helds
>on the boat but not here at home.
>
>Slim
>
>On 4/8/05 11:32 AM, "Bill Effros" <bill at effros.com> wrote:
>
> > Slim,
> >
> > From comments sent previously, you can infer the problems manifest in
> > all compasses: they will all kick out numbers, but there is no fixed
> > relationship between any two numbers until you discover what that
> > relationship is.
> >
> > Let's start with your compass.  First rotate it 360°, slowly.  Is it
> > capable of stopping at any number?  If the magnet has been badly
> > damaged, it will jump over some numbers, no matter which way you point
> > it.  If that's the case, you will not be able to use this compass
> > because you will never be able to find another compass that makes the
> > same mistakes in exactly the same way.  Consistency is the critical
> > function of any compass.
> >
> > Assuming that your compass is capable of pointing in 72 different
> > directions (5° intervals) you must next determine if it is consistent.
> > Point the compass so it reads 0°.  Make a line in the sand.  Turn the
> > compass 180°, and write down what number the compass points to.  Turn it
> > back to 0° using your line in the sand.  Does it say 0°?
> >
> > Please note, if the compass is working properly, the compass card should
> > not move at all -- only the housing and the board you may have mounted
> > it on should move.  It may not be pointing in a predetermined direction,
> > but it should be pointing in the same direction all the time.  That's
> > the way properly functioning compasses work.
> >
> > Using a protractor, draw a line in the sand at a 90° angle intersecting
> > your first line.  Put your compass on this new line, first one way, then
> > the other.  It should read 90° and 270°.  If it doesn't, you've got a
> > problem.  Make more lines at 45° angles.  The compass card should not
> > move.  Your computed angles should equal what you see on your compass.
> >
> > If they do not, someone may have "corrected" your compass.  The
> > adjusting magnets, built into the housing of your compass, must be
> > pulling your compass card in different directions as you rotate the
> > housing around your compass magnet. Try to twiddle with them, so that
> > they don't change the orientation of your compass card when you rotate
> > them around.  If you can't make this happen, it's time for a new 
>compass.
> >
> > If your compass is consistent, it's time to mount it on your boat, and
> > figure out what direction it's actually pointing.
> >
> > Timid Virgins Make Dull Companions.  Lesson II.
> >
> > Bill Effros
> >
> >
> >
> > __________________________________________________
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>
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