How do you use a plotter???

nospam4me

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Mar 20, 1998, 3:00:00 AM3/20/98

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Here's one I know someone can help me with... how do you use
those cheap plastic plotters to get a true course heading from a
sectional? You know the kind I'm talking about - looks like a ruler
with a half-circle compass stuck in the middle.

The thing that really throws me off is that it seems that the
degrees are marked backwards. 170 degrees on the left side of the arc
and 10 degrees on the right (and the corresponding 350 degrees on the
left and 190 degrees on the right).

I know it should be simple, but I'm obviously missing
something here.

Thanks in advance!

Dimitri I. Rakitine

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Mar 20, 1998, 3:00:00 AM3/20/98

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This is a troll, right?

nospam4me (lgiv...@datasnyc.com) wrote:
: Here's one I know someone can help me with... how do you use

Ron Natalie

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Mar 20, 1998, 3:00:00 AM3/20/98

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> The thing that really throws me off is that it seems that the
> degrees are marked backwards. 170 degrees on the left side of the arc
> and 10 degrees on the right (and the corresponding 350 degrees on the
> left and 190 degrees on the right).

Place the long end of the plotter on the course. Slide the ruler
part along the course until the center of the protracter is on
the longitude line of the chart and read where the longitude
line hits the scale. Most also have a second 90 degree off
scale for using lattitude lines (handy with primarily n/s
courses).

Dave Bedard who writes a humor column for Private Pilot had
a great article on plotters. My favorite part was the section
that went something like: Use the 1:500,000 scale for sectional
charts, use the 1:250,000 scale for TAC's. For charts marked
"Not For Navigation" use the scale marked "Not for Plotting."

Louis A. Ramsay

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Mar 20, 1998, 3:00:00 AM3/20/98

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In <35128B25...@sensor.com> Ron Natalie <r...@sensor.com> writes:
>
>
>Place the long end of the plotter on the course. Slide the ruler
>part along the course until the center of the protracter is on
>the longitude line of the chart and read where the longitude
>line hits the scale. Most also have a second 90 degree off
>scale for using lattitude lines (handy with primarily n/s
>courses).

I was always told NEVER to use a parallel for measuring an angle
as the parallels are NOT straight lines on Sectionals - they are
curved.

Lou.

Ron Natalie

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Mar 20, 1998, 3:00:00 AM3/20/98

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Louis A. Ramsay wrote:

> I was always told NEVER to use a parallel for measuring an angle
> as the parallels are NOT straight lines on Sectionals - they are
> curved.
>

Yes, but at each place they are drawn the do represent E/W.
The curvature isn't such that it's going to make more than
a degree or two error over the radius of the plotter scale.

Even on the Wall chart in my office which is 1"=32NM, the
curvature of the latitude over a few inches is by and large
non-existant.

CMSGBEATY

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Mar 22, 1998, 3:00:00 AM3/22/98

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Something you might have trouble with using those plotters is directly
reading the heading. What I mean is you can read any one of four courses
(angles) where the latitude or longitude line intersects the course line.
There is an inner scale with two courses 180 degrees apart and an outer
scale with the other two courses 180 degrees apart. What you absolutely
have to do is examine your course direction on the sectional so you can get
an approximate idea of what the true course is already, say within 45
degrees. Then it's as simple as choosing the true course on the plotter
which most closely matches your 'guesstimation'. The benefit from guessing
TC and then checking TC with your plotter is that you get a better feel and
intuition for navigating.

One of my students still has trouble determining the correct TC from the
fixed plotter. What I'm telling him now is to guess first, measure 2nd,
guess again and measure again (double check).

Good flying to ya,

Craig Beaty

Louis A. Ramsay wrote in message <6eum03$c...@dfw-ixnews11.ix.netcom.com>...

>In <35128B25...@sensor.com> Ron Natalie <r...@sensor.com> writes:
>>
>>
>>Place the long end of the plotter on the course. Slide the ruler
>>part along the course until the center of the protracter is on
>>the longitude line of the chart and read where the longitude
>>line hits the scale. Most also have a second 90 degree off
>>scale for using lattitude lines (handy with primarily n/s
>>courses).
>
>

> I was always told NEVER to use a parallel for measuring an angle
>as the parallels are NOT straight lines on Sectionals - they are
>curved.
>
>

> Lou.
>
>