Charting headings/bearings/direction with 360 flip

**marky9074** · 12-26-2012, 06:18 AM

Hi there,

Have for a while now been trying to chart current data extracted from a model which in it's simplest form is just bearing and speed (rate in knots). The trouble is handling the data where it crosses over 360 degrees (North) etc. I have been looking at various wind rose plots, but not really found anything to suit, and realistically I am not looking to use a radar plot, though I guess it is an option (but only for twelve hours at a time).

I have attached some sample data, with the bearing and speed in red. I did some quick calcs to return the bearings as compass points thinking that this might be easier to do something with, but I am still a little stumped. Within the excel sheet I have inserted a screen grab of a display of current direction & rate (and tide). Ideally I would like to be able to create something like that. Basically I am after some ideas and if anyone can help or point me in the right direction it would be much appreciated.

Cheers,

Mark

**Andy Pope** · 12-27-2012, 05:22 AM

This may help get you started.

I modified your directional table slightly to handle North directions crossing between 348 and 11.
I also used a different formula to get the direction letter, this highlighted a few differences in direction.

I have only done N,E,W and South but the approach can be extended for all the other directions.
The chart is a xy-scatter with conditonal series to display marker when the wind changes.

This old example of mine show how to use custom markers if you want to use more arrow like markers. For you chart you only need to apply the different arrows to each series once, so no need for macro code.
http://www.andypope.info/ngs/ng10.htm

You can even extend this example by making the data display correct values for a given day as currently it only does the first day.

**marky9074** · 12-27-2012, 07:36 AM

Thanks Andy,

But looking at your example on the web site, it looks like I can just plug my stuff straight into this? Certainly looks OK, once I fudged the heading in the code...

Cheers,

Mark