# Re: Maps! (let's have a seperate thread, instead of using roll call)

I am totally pants at maths,
but to be 185 yards out after a mile's walking with a 2 deg error!
That is a huge distance... I had no idea.
I had imagined it would be a few feet and that these accurate devaitions
were just for airline pilots and ship's captains.

I think your error was 6 degrees.

There is no need for calculator that does trig to work out the
approximate error.

Consider the 1 mile as the radius of circle, the circumfrance of which
will be 6.28miles.

If your 1 degree out the error is (1/360)*6.28=0.0174mile or 30.7yds.

Thats close enough for small deviations.

So, I need to teach 2 deg now?

Its currently (from the data on the 2004 map) 2 deg 10 sec in the
centre of the central beacons sheet.

Using 2 degrees is close enough for all practical purposes.

As to using compasses in what you call 'lowland areas', I would say it is
just as important as anywhere.

Yes, what I really meant is that a serious navigation error in an
upland\mountain area could have life threatening consequences.

I walk quite a bit in lowland areas myself, I particullaly like coastal
paths. But navigational errors on a coastal path are unlikely to have
any serious consequences.

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