Please Help: Magnetic Course Display in OpenCPN

[Jim Cate]

Dave, that sounds pretty darn good to me. Thanks for taking our irreverent desires seriously.

Cheers,

Jim (and I know that Ann will be tickled too)

[Viking Sailor]

Originally Posted by bdbcat

Wow...

I knew this one would not be as simple as adding T+V=M.
Thanks for all the feedback. As Pavel notes, my issue is philosophical rather than practical. COG(M) still bothers me, especially for AIS targets.

Anyway, here is my current proposal.

1. There will be a user specified variation entry field (USER_Var). It will be a constant for current instance of OCPN.
2. If user adds the WMM PlugIn, then the variation will be automatically calculated based on own-ship position. This value will override the USER_Var.
3. COG displayed on the bottom status line will be COG(M) (Much as this pains me...)
4. Bearings and Courses in the Route Properties dialog, route leg rollovers, and Active Route console will be (M), corrected for variation.
5. AIS target reports will show target COG(M). sigh....
6. OCPN knows nothing about deviation. If you have a steel boat, I guess you had better learn a little math

After I test this stuff locally, I shall never ever use it. But I hope some will find it improves their OpenCPN experience.

btw, I'm sure all realize that if you have your GPS receiver set to send Magnetic info, you will want to revert to True output, and depend on OCPN to do the math.

Ready for the next round?
Dave

Dave,

Great!

Sure I can't talk you into putting in one tiny deviation table? Only 8 entries. It could even be set up in the .ini file. What's a little table and a few "if" statements among friends? Please think about it. Please!

Thanks,

Paul

[bdbcat]

Folks...

One modification to my proposal:

If a user has a GPS receiver that reports Variation as part of RMC sentence, that value will override the USER_Var. And the WMM PlugIn will be ignored in this case.

Thanks
Dave

[JPA Cate]

This is beginning to sound as if it will really happen...at last! Thank you all so very much.

Ann

[bdbcat]

Hi, its me again....

Source code builders may check out and build the lastest github source to exercise the True/Magnetic option implementation (FS#1025) prior to the next official Beta release. The pre-Beta is ready now as 3.3.910.

Good Luck
Dave

[sy_gilana]

Dave, you're a gentleman. Personally I live in the T world, Radar, ECDIS, Paper charts, AIS, every thing is in True. Personally I would prefer to hide the M values completely as I know that everything on board is true except for the compass. My conversion to M is simply to look at the compass and then at the COG and make a note of the total difference.

I suggest that the whole Magnetic debate in this thread is a moot point without a deviation table somewhere.

Your desire to improve the "user experience" is loudly applauded by me despite having no interest in the M-word as far as OpenCPN is concerned.

Could it not be a Plug in? and therefore completely optional?

over....

[mileskb]

Originally Posted by bdbcat

Hey there, folks...
None of the above applies to bearings, however. That is what one reads from a hand bearing compass. Or what you might see on a printout of a proposed route, with steering instructions. No problem there whatsoever.

So, what say you all?

Dave

My specific request was for exactly as you say above. Using a hand bearing compass, especially in the Binoculars and printing route information.

What say you?? he asks...

I say I will sing the praises of Dave... His children's, children's, children's, children will be reminded of the day Dave added Magnetic bearings to OpenCPN...

Nearly everyone I know uses a Compass for steering and everything based on true. Even the Piloting course I took last year had us actually plot the points on the chart using True (so the they look nice) but LABEL THEM MAGNETIC so they could be used.

THANK YOU !!!

[rgleason]

I really do hope that after the dust settles on this effort, that someone like Viking Sailor will write the Opencpn Documentation supplement to "Magnetic Course Display" with care and clarity, and with the assistance of ALL who have been asking for this change, otherwise there will be "user confusion".

You can start thinking about where the new section goes, and start taking careful notes from this dialog, and participate in testing, where the rubber meets the road... -Who is going to volunteer to update the documentation?

[Stargazer1942]

Originally Posted by bdbcat

Wow...

I knew this one would not be as simple as adding T+V=M.
Thanks for all the feedback. As Pavel notes, my issue is philosophical rather than practical. COG(M) still bothers me, especially for AIS targets.

Anyway, here is my current proposal.

1. There will be a user specified variation entry field (USER_Var). It will be a constant for current instance of OCPN.
2. If user adds the WMM PlugIn, then the variation will be automatically calculated based on own-ship position. This value will override the USER_Var.
3. COG displayed on the bottom status line will be COG(M) (Much as this pains me...)
4. Bearings and Courses in the Route Properties dialog, route leg rollovers, and Active Route console will be (M), corrected for variation.
5. AIS target reports will show target COG(M). sigh....
6. OCPN knows nothing about deviation. If you have a steel boat, I guess you had better learn a little math

After I test this stuff locally, I shall never ever use it. But I hope some will find it improves their OpenCPN experience.

btw, I'm sure all realize that if you have your GPS receiver set to send Magnetic info, you will want to revert to True output, and depend on OCPN to do the math.

Ready for the next round?
Dave

Dave:

Wow, when I started this thread, I had no idea of the complexities of the issue. And frankly I don't have the programing skills to follow some of the discussion. So, please forgive my ignorance. What I was hoping for, was check box that when checked would display the bearing information in magnetic, based on the information in the plugin depending on the vessel's location and when unchecked would display the bearing information in true, without changing the underlying calculations. Is that, essentially, what you have proposed?

Norm

[CarCode]

Norm,
it is already in 3.3.910 sources and works fine. Picture from my localized german version still without localized text for this check-box.

[Icnoships]

Dave ..more good stuff....many thanks !!

had a play with 910 on OS X.7.5 today, compiled with no errors and all seems normal.... i am sure u are aware that O is not checking that a Var variable (Var value) exists before displaying COURSE M, I noticed this as i had no mag input (GPS or plugin) an when hovering over a course T & M are the same ......

when i then compiled with wmm_pi all is working as expected sort of..
on the first run, after enabling wmm plugin WX is throwing up an assert, plz see pic..... clicking cancel appears to give full functionality.

also ... 4 Pavel when compiling the wmm plugin on the Ithing the dylib is not getting dragged into the app bundle, had to copy an paste from build/plugins/ , think its in the build/wmm_pi/CMakeLists as all other plugins (that compile on mac) are being pulled in.

Mo

[CarCode]

Mo,

comment out the lines with GetInfo in jsonval.cpp:

// wxLogTrace( traceMask, _T("(%s) actual object: %s"), __PRETTY_FUNCTION__, GetInfo().c_str());

to silence the assert.

I do not use command line tools on Mac OS X but Xcode to build a running bundle of OCPN. The new Xcode 5.0 with SDK 10.9 (Mavericks) works fine.

Gerhard

[cagney]

Originally Posted by Icnoships

Dave ..more good stuff....many thanks !!

had a play with 910 on OS X.7.5 today, compiled with no errors and all seems normal.... i am sure u are aware that O is not checking that a Var variable (Var value) exists before displaying COURSE M, I noticed this as i had no mag input (GPS or plugin) an when hovering over a course T & M are the same ......

....

The default variation is set to 0 if no other rules kicks in, that explains why T & M are equal.

Thomas

[Icnoships]

Thanks Gerhard will give that a try when i get a moment :thumb

Thomas .... so what u are saying is M is really T when no variation input is available even though it is displayed as M, think maybe it should default to T or a warning pop up minimum.

Mo

[bcn]

Originally Posted by Icnoships

Thomas .... so what u are saying is M is really T when no variation input is available even though it is displayed as M, think maybe it should default to T or a warning pop up minimum.

Mo

How should the program know? If the users choses to have the bearings in M they are M, even if the variation is 0 and M=T.
And being 0 may have two reasons: or it is really 0 at this place or the user has not changed the default value AND the WMM-Plug-in is not in place