Thread: Anchor Circles
View Single Post
Old 09-01-2016, 10:51 AM   #34
psneeld
Guru
 
psneeld's Avatar
 
City: Avalon, NJ
Country: USA
Vessel Name: Freedom
Vessel Model: Albin 40
Join Date: Oct 2011
Posts: 17,389
Quote:
Originally Posted by WesK View Post
The question is, how much does the circle distort and is it relevant too actually anchoring a boat?


Is it one foot? Five feet? Ten feet? One hundred feet?
Depends on the lattitude.

Then it depends on the rode out.

In much of Puget Sound from what I can tell it is around 30%.

So draw a 100 foot circle and in one dimension, it is only going to be a 70 foot radius.

Now...the million dollar question that needs to be asked,....is the circle distorted in conjunction with the chart? Is it calculated in lat/long or arithmetically inside the device.

I have to think about this some more and draw things out whether the problem is self correcting or not if on plotters, and what apps are doing to you also.

I know in high lattitudes that most nav is off grid charts because the low angles associated with GPS signals, but also because of distortion of charts.....If I recall correctlyfrom my polar expedition days....hmmmm...now this has got me realky thinking.
psneeld is offline   Reply With Quote