NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Sumner's Line modified to Question of Precision and Accuracy
From: Jim Hickey
Date: 2006 Feb 10, 16:22 -0500
From: Jim Hickey
Date: 2006 Feb 10, 16:22 -0500
Andre wrote:
Here is a question for the group:
How precise/accurate do any of you attempt to get in your calculations? I realize that depending on what particular task you are engaged in at that moment, your accuracy and precision will vary (i.e. Noon Sight, versus Lunar Distance for Time).
My goal is to take measurements that will put my position within 2 miles of reality, is this good for a small sail boat? I realize that it would not be good for a big ship such as the Exxon Valdez.
Hence my questions. Thanks ahead of time for your answers.
Andrew
The simple answer is as accurate as possible.
This is a favourite topic for the forum and there has been lots written on the topic. Your question has to be put into context a little. Conditions play a great role as do the methods being used.
Under great conditions, i.e. easy rolling seas, clear conditions, I have been able to take sights on my 42' sailboat that have fixed my position consistently within about 1.2 nm or better. That is with no averaging, two or three sights taken and reduced.
If conditions get rough, clouds start to move in and the horizon is not sharp, getting within 2 nm's could be a major victory. If it were still necessary to get within your 2 miles then more sights and more data handling is the order of the day. So method plays a greater role.
