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Old 25-07-2016, 11:20   #1
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DR plugin-Not the right distances??

Hello all

first of all I would like to say that I am a new user and very impressed from the great job that people here have done.

I was trying the DR plugin which is very useful tool!
Meantime I realized that the distances between the DR points (in gpx file that creates) are difference than it should be expected.
To be more clear I give below the following example:

Interval: 6 hours
Speed: 5 Knts

Normally it should be expected the distances between DR points to be exactly 30nm.

The DR gpx files shows a fluctuation of distances (it depends of what distance of DR points measure) from 30.04nm up to 30.12nm for a total route distance of 2500nm.

Is something I am missing???

I would really appreciate if someone could give me a answer.

Best Regards

Nikos
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Old 25-07-2016, 12:52   #2
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Re: DR plugin-Not the right distances??

I had not considered the use of DR over such long distances!

There are probly some issues with calculating each DR position that are causing these errors. I need to have a look.

Mike
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Old 01-08-2016, 06:00   #3
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Re: DR plugin-Not the right distances??

Formulae for calculating distances and bearings have been updated. Still a very slight error in the distance if the course on any leg is exactly east or west. A work in progress.

I have attached the updated dll (please remove .pdf from the file name).

For OpenCPN 4.2.0 and upwards.

Nikos ... could you give this a test.

Mike
Attached Files
File Type: pdf DR_pi.dll.pdf (171.0 KB, 18 views)
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Old 02-08-2016, 04:32   #4
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Posts: 381
Re: DR plugin-Not the right distances??

GitHub has been updated and a Windows compiled dll placed in the releases section.

A small error remains when the course changes to exactly 090 or 270.

Pavel ... could you update the installers at opencpn.org idc?

Mike
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