Plugin for Current Speed and Direction (Set and Drift, or VDR)

[TBillings]

Hi all, I have a multiplexer that computes the VDR sentence, which is Set and Drift. Is there a plugin that can plot it as a vector over my boat?

I took it out for some testing in the San Francisco Bay, and went to a predicted current point and it checks out. But I was simply reading it off the NMEA stream coming into OpenCPN.

Is there any way to plot the vector over my boat? Course Made Good and Speed Over Ground are plotted as a red long dash vector; Heading (True) and Speed Through Water are plotted as a red short dash vector; so is there a plugin out that that could plot the Current Set and Drift as a dotted line vector, or hollow line? Or any sort of vector?

[tom_BigSpeedy]

Matthew,

there are several plugins out, which you can use as an example.
E.g. TackandLay_pi, which is probably closest to what you want to do.

So you're reading the tide station/current point predictions and want to plot current direction and speed on the boat ?
How would you do, when sailing away from one of these points ?
Do you want to calculate average values between the points ?
Accuracy will be a matter of the station/point grid size ...

Or do you want to plot it on that current point ?

Thomas

[TBillings]

Yeah, the idea is to plot it over my boat, constantly updating with each NMEA sentence. Here's a sample I pulled from the log:

$INVDR,202,T,188,M,2.31,N*17

so the current is flowing towards 202 degrees true (188 magnetic) at a speed of 2.31 knots. This sentence updates every .5 seconds, so it's even a little quicker than my course made good/speed over ground.

And just like your course made good/speed over ground plots a dashed red vector on your boat from the RMC sentence, I'm interested in doing the same thing but for the current direction/speed.

I'll take a look at the Tack and Lay plugin, even though my background as a programmer is quite limited. How hard could it be?

[RobertLeask]

I didn't know it was possible to plot heading and water speed in OpenCPN. I can't find a setting for turning it on, is there a plugin to enable that? I'm presently in dry storage and installed a speed log with NMEA output, would love to see a heading vector and water speed, I could estimate set and drift well enough. I thoght you had to pay bug bucks for high end professional software to do that.

Would love to have that, and another great thing would be a MOB drift estimator, based on real time drift rate. The only software I know of that does it is Transas Navisailor, way out of my budget.

[tom_BigSpeedy]

Robert,
I started working on a plugin last September. It will show you (sea) current speed / direction, as well as add some performance data like momentary VMG
versus target VMG (based on your boar polar), boat and waypoint laylines, etc.
It will also calculate true wind speed/direction, if you don't get it from your instruments yet.
Basically it's a copy of dashboard_pi, with some enhanced features.
I worked a lot on it during winter time, but I really need some live testing on my boat (which is out of the water right now) to verify some of the algorithms.
So please be patient, I'm still working on it...

Thomas

[BMayer]

Originally Posted by tom_BigSpeedy

Robert,
I started working on a plugin last September.
.../...
Thomas

Hello Thomas
And your plugin progress ?

[rgleason]

Thomas has this plugin working and has been out on his boat refining it. I have been testing it for him using vdr nmea files.
I do not know what Thomas' s next steps are for his plugin, but I expect he his working on some of the details for the plugin. Perhaps he will advise further.
I am excited and impressed by this plugin.
Suggestion: Calibrate all your instruments first. Do this now.

[BMayer]

Originally Posted by rgleason

Suggestion: Calibrate all your instruments first. Do this now.

Thanks !

[tom_BigSpeedy]

Hi guys,
the windows version is almost ready to go for a wider test here in the community. I solved the "Target CMG" problems I had, this is working now as well (verified manually with a plot of my own polar ! ).
I'll have to finish some minor issues and update the documentation, but then it's ready to go.
I guess early next week ...
Thomas

[rgleason]

Here are some images from tom_bigspeedy's plugin, to wet your whistle!
Along with Sweep Plot to the left.

[BMayer]

Originally Posted by TBillings

Hi all, I have a multiplexer that computes the VDR sentence, .../...

Hello TBillings
What are this multiplexer (brand and model, please) ?
Thanks by advance
Bernard Mayer

[TBillings]

I'm using a Raspberry Pi with a few python scripts doing all the work. It's a relatively simple setup you can get for about $100, so long as you already have a paddlewheel on your boat. Here's the how-to guide written for total newbies to make one yourself. King Tide Sailing: A Raspberry Pi Wireless NMEA-0183 Multiplexer (USB GPS, Digital Compass, and Sailboat Instrument Input)

[BMayer]

Originally Posted by TBillings

I'm using a Raspberry Pi with a few python scripts doing all the work. It's a relatively simple setup you can get for about $100, so long as you already have a paddlewheel on your boat. Here's the how-to guide written for total newbies to make one yourself. King Tide Sailing: A Raspberry Pi Wireless NMEA-0183 Multiplexer (USB GPS, Digital Compass, and Sailboat Instrument Input)

Thanks a lot !
i know what i made next winter

[tom_BigSpeedy]

Hi there,

here is a first shot of my tactics_pi plugin ...
Windows only, for the moment.
Well and not the plugin itself, as I can't upload 635 kB as ".doc", but at least the documentation I wrote tactics_pi.pdf.
I'll talk to Rick (rgleason), if we can use his file thingee to share.

The documentation will guide you through the functionality, what it can do and where the limits are ...

To really use the functionality, you'll need a polar file. I tested those polars coming with the weather routing plugin, they should work.
In general I took the polar-loading-code from polar_pi and adopted it to what I needed for the plugin. I wanted to keep the plugins compatible. But basically any polar created / readable with polar_pi should work (I did not really test "Expedition" format polars, as I had none). As a fallback I'll attach my own polar and a VDR sample file to Rick's share.

Please remember this is a copy of dashboard_pi. Currently there is a limitation in dashboard_pi where you cannot add any further instruments without some bigger rework ... As I copied the code, I still have the same limitation, which means that I had to remove some of the standard dashboard instruments from tactics_pi, to free up the space for my new instruments.

But you can run dashboard and tactics_pi in parallel, no problem. I do it all the time.

It's still missing its plugin icon, so it falls back to the default "green puzzle thing" ...
But that was priority B for me...

I'll be leaving tomorrow night and will be out all next week for a 500 miles race, which starts on Sunday, giving the plugin a hard core test.
So I won't be able to answer questions. I'm not sure if I will be able to clean up the code and upload it to my github account till tomorrow evening (I guess not), but I will do after my return.


Rick, thanks a lot for testing the pre-alpha code for me


I'll reply again here as soon as it's clear where to download the plugin for testing.

Thomas

[rgleason]

Thomas Rauch has released Tactics_pi as an alpha version for windows.
It can be downloaded at OpenCPN File Thingie

I have to say that the plugin and documentation is excellent, and while there may be some small glitches, the plugin is very stable and effective. I encourage you all to try it with the sample VDR files (sample1 -upwind & reach, sample2 - downwind , and then with some experience and after calibration of your instruments, use it on your boat.

Note: If you can record your nmea data and upload good example files (sailing upwind in steady winds and conditions, sailing downwind in steady winds etc. that would be very helpful. We are trying to build a library of good sailing data for the purpose of testing. Please describe the files for us. Thomas has provided two good sample VDR files.