# NavList:

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

Message:αβγ
Message:abc
 Add Images & Files Posting Code: Name: Email:
Re: Figuring Course given Lat/Long of destination
From: Roger M. Derby
Date: 2000 Feb 27, 7:24 PM

```Note that for great circle sailing, you only compute your "departure heading".
The heading you sail changes continuously (or as often as you refigure it.)

Roger
----- Original Message -----
From- Luis Soltero
Sent: Sunday, February 27, 2000 8:42 PM
Subject: Re: Figuring Course given Lat/Long of destination

There are several ways to solve this problem.  3 come to mind
a) Using plane sailing formulations which are very inaccurate due
to reasons you mention below.
b) rhumbline computations using meridionals which compute
distances based on Mercator projections.
c) great circle sailing which will compute the shortest distance
between both points very accurately.

Alton B. Moody in navigation afloat also discusses something called mid latitude sailings
which if memory serves me right uses the mean of the two given longs
in the calculation.

Anyway, all these sailings are discussed in great detail with formulas and examples in
Bowditch.

Cheers,

--luis

----- Original Message -----
From- Ed Kitchin
Sent: Sunday, February 27, 2000 5:49 PM
Subject: Figuring Course given Lat/Long of destination

An interesting problem appears in the latest issue of "Ocean Navigator"
Which asks that you figure the course to a destination given origination and
destination. It would seem easy to determine the difference in lat. (The
destination was over several degrees of lat.), but deg. of long. differ in
length as you change lat. One could simply take the mean of the two given
long. and use that, but that bothers me as not being all that accurate. There
is the error of the Macerator thing. You could use universal plotting sheets
and construct using a vertical representing diff./lat., then draw a
horizontal from the top of the lat. fig., representing the long. at the
destination, and draw a hypotenuse as the course line. (???) Are there any
mathematicians out there to
give me a good formula to learn for this task? Thank you.

Ed Kitchin
```
Browse Files

Drop Files

### Join NavList

 Name: (please, no nicknames or handles) Email:
 Do you want to receive all group messages by email? Yes No
You can also join by posting. Your first on-topic post automatically makes you a member.

### Posting Code

Enter the email address associated with your NavList messages. Your posting code will be emailed to you immediately.
 Email:

### Email Settings

 Posting Code:

### Custom Index

 Subject: Author: Start date: (yyyymm dd) End date: (yyyymm dd)