# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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When to turn?
From: Anders Reed Mohn
Date: 2002 Mar 19, 18:25 +0100

```Greetings, navigators.

I stumbled across this list, searching the net for

I'm totally stumped here, so I hope maybe someone
can explain it a bit to me.

Yesterday, I was shown the formulas for calculating
GC-routes/initial course, vertex latitude etc..
So far, so good.

But then, my teacher came up with a formula for
calculating _when_ to turn one degree towards your
destination, while sailing that route.
I.e. in an example he gave, the initial course was
about 62 degrees, total distance would be som 3700 Nm,
and he showed that at every 115 Nm, we would have to
turn one degree towards our target.

Now, I fell off the train of thought here, so I
never got around to writing down the exact formula,
and I haven't been able to find it on the net.

My big problem here is that the formula contained
speed as a factor. The sample above was calculated
for 5 knots speed. I don't see how speed fits into
any of this...

Does this sound familiar to anyone?

The formula was something like  60/(x*V*x)
where x and Y are trigonometric expressions (sines and cosines),
and V was boat speed.

Anyone??

Cheers,
Anders RM :)

```
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