OpenCPN

[sinbad7]

I am IMPRESSED and grateful for the designers and contributors of this,for a layman rather complicated charting conondrum. Makes the sea a safer place for all of us.
A BIG thanks....

Tore

[wonkodsane]

Gents,

Thanks for the software, it is a wonderful utility for folks not wanting to pour more money into their hole in the water than absolutely necessary.

I had a question for the community.

Is anyone working on homebuilt or hacked wind, speed, and sounding gauges? Something connectible via USB or RS-232? I look at most of the gauges available and see that a large proportion of the circuitry in them is devoted to displaying the data, not retrieving it. How hard would it be to build USB interface for sounding, wind, and speed gauges and then either integrating it with OpenCPN or building a companion application along the same lines?

I have just enough knowledge to be dangerous here, anyone else working on something like this? I don't want to pay RayMarine a few thousand dollars for readings from equipment that only costs a few hundred at most.

Thanks again!
-Scott

[idpnd]

Originally Posted by wonkodsane

Is anyone working on homebuilt or hacked wind, speed, and sounding gauges? Something connectible via USB or RS-232? I look at most of the gauges available and see that a large proportion of the circuitry in them is devoted to displaying the data, not retrieving it. How hard would it be to build USB interface for sounding, wind, and speed gauges and then either integrating it with OpenCPN or building a companion application along the same lines?

I have just enough knowledge to be dangerous here, anyone else working on something like this? I don't want to pay RayMarine a few thousand dollars for readings from equipment that only costs a few hundred at most.

I am thinking along these exact same lines. This can be implemented now.

Theres navmonpc (windows only) by Paul Elliot (he's a member on this forum) with support here and discussion of a cross-platform/open source client here; this programme displays NMEA data from sensors. This could be used in conjunction with a standalone sensor such as NASA's [UK discount marine supplier; no affiliation with yours truly] NMEA masthead sensor to get instrument display on the onboard pc without the expensive display units etc. This software could be run on a daylight-compatible/waterproof secondary display in the cockpit.

Other example applications might be the use of an NMEA log and echosounder with a digital NMEA output ("actisense" discovered by a quick google; any product recommendations welcome). The company is also selling NMEA multiplexers and NMEA->USB converters. The usb interface appears to be linux-compatible even!

The free programme (but not free software) Seaclear II is also capable of displaying NMEA data.

[idpnd]

PS regarding NMEA gauges/OpenCPN:

There is an open source implementation of NMEA gauges in another attempt to produce an open source navigation system; perhaps this could be adapted/integrated or cooperation might be feasible? The developer has also implemented GRIB-file support.

Take a look here or at sourceforge

The NMEA gauges widget actually has proper documentation [pdf] even!

Best regards,

Max

[bdbcat]

All...

I am implementing the Tracks recording function, and a question has come up.

It has been suggested that the Track Snapshot interval should be set to a very small number, on the order of 10 seconds.

Implementation-wise, it makes no difference. It is just a number, and memory is cheap, processors are fast.
Of course, if the Tracks are not saved to GPX and deleted from active use, then opencpn program startup and shutdown times will suffer, but that is within the control of the user.

However, I have some trouble understanding this concept. I cannot see what use such a track would be, either displayed on the screen, or saved for later use.
a. Waypoints would be very close together, thoroughly cluttering the display.
b. The distance between waypoints would approach the GPS position resolution.(10 sec at 5 kts = 25 meters...)
c. For me personally, we cruise roughly 1000 hrs per year, yielding 3.6 million waypoints.

Clearly, I am not using opencpn in the way that others are...
What am I missing?

Dave, the hornet's nest kicker......

[gjorgensen]

I can really only answer for myself on the question of tracks. Personally, I use tracks for two purposes:

1) To analyze the course we sailed during and after a sail, in my case usually to analyze where we went right and wrong in a distance race. During a race a track gives me trends. After a race I review the course, learn what I can, and delete the track. I often save it off to look at the next year, but I don't keep it around inside my nav program. So in this case many points are useful, because they give me a more accurate view of what happened.

2) To produce specific waypoints for replicating a specific route or finding danger areas. I would never create a route using every track point in a track (thousands of points). But a fairly accurate track is useful for going back and drawing a route with a few waypoints that follows the important contours of a track, e.g. where the edge of kelp bed really was. I need fine time scale to be sure I don't miss important features.

Because of the way I use tracks, I really differentiate between tracks/trackpoints and routes/waypoints. I wouldn't want to store a track as thousands of waypoints, because it's really not useful for the most part. But a detailed track would allow me to create a more accurate route of only a few waypoints.

[scotte]

Originally Posted by bdbcat

It has been suggested that the Track Snapshot interval should be set to a very small number, on the order of 10 seconds.

What about allowing configuration of distance and/or time? Personally, I would set time to no more often than 1 hour, but I guess it all depends on what you are trying to do with it...

[Harryjak]

When Sea Clear pulls up a track it just shows a line, no waypoints. The waypoints show when you decide to make a route out of it, requiring a lot of deletions. My interest in tracks is so I can duplicate getting into tight harbors in SE Alaska when I have gone in with somebody with local knowledge.

[idpnd]

Originally Posted by bdbcat

Of course, if the Tracks are not saved to GPX and deleted from active use, then opencpn program startup and shutdown times will suffer, but that is within the control of the user.

It would be easiest if a fresh track was initiated for every startup/execution of the software, and automatically saved in a timestamp format upon shutdown.

Originally Posted by bdbcat

However, I have some trouble understanding this concept. I cannot see what use such a track would be, either displayed on the screen, or saved for later use.

Generally, the GPX tracks could be shared on google earth, and there would be a track record of the overall cruise or even circumnavigation. I would actually use a separate programme such as geohist to log all gps data (i.e. including speed) to a database for later reference.

Originally Posted by Harryjak

When Sea Clear pulls up a track it just shows a line, no waypoints. The waypoints show when you decide to make a route out of it, requiring a lot of deletions.

Is this a technical limitation in the current opencpn implementaton? If you are using the standard opencpn routing, I suppose you would have to make a waypoint at every course change (or rather, a lot of waypoints to capture the actual route travelled).

Originally Posted by Harryjak

My interest in tracks is so I can duplicate getting into tight harbors in SE Alaska when I have gone in with somebody with local knowledge.

Specific GPS waypoints for entering reefs or tight natural harbours are quite commonly shared amongst cruisers. Distributing local knowledge in GPX (or KMZ) format online would of course be fantastic.

Thanks for your attention!

[phiggins]

Dave has created a build for Visual Studio on Windows and I was able to compile and execute a debug version and give him the data to fix the address exception. Great work Dave, I don't know where you find time to do all the stuff you do.

As for the track, I think the user should be able to set the minimum time, minimum distance and the compass change (in degrees) that will cause a track point to be generated. That way you set a fairly large time but still be able get a reasonable track that could be used to create a route.

Also, I think you should be able to import a track in GPX format but make a decision at load time, like Google Earth does, whether you want to load the waypoints or not. If you no way pounts are loaded I think the track should only be shown as a line, no waypoints and no arrows.

And I think you should have a way of turning off the route and track so you use the max detail. The way it is now when you have route displayed and you are at a small scale if you move the cusrsor over the route it won't let you do a max detail because it is detecting the route.

[sinbad7]

Dave..
Here is an interesting article on the subject of saving tracks...
Accuracy of Tracks From a Garmin Etrex GPS Receiver: Saved Tracks Vs. Tracks in Memory

It's a matter of compromise I guess. It's easy enough to adjust and fine polish a saved route. Often a little variation is desired between the points.

[sinbad7]

Dave..
Here's another facility which may be of interest to the project...
GPSBabel: convert, upload, download data from GPS and Map programs

Tore

[Viking Sailor]

Hi Dave,

I hope that all is going well for you and you are able to find time to do some sailing. Your hard work is very much appreciated.

I agree with Paul (phiggins) on his approch to implementing tracks. My comments are intended to expand a little on his suggestions.

When track mode is enter the current positon is used to set the track reference positon and a new track file is started. A line is drawn from track reference positon to the currect positon whenever the current position moves by at least the selected distance (~100 ft), or the selected time interval (~10 min's or 1 hour) has elapsed. If the COG has changed by at least the selected number of degrees (~2), the current position becomes the new track reference position and the track file updated.

Upon exiting the track mode, the track file can be save or deleted, and the displayed track cleared.

The track reference positions are saved in the track file. It should be possible to load, edit, and re-save the track file. When editing a track the track reference positons should work like waypoints. The user should be able to move, add, or delete track reference positions.

Thank you again for all your hard work. Also, I hope you will forgive any inane comments or suggestions from yours truly.

Best regards,

Paul

[raisin56]

If editing is allowed on a tracks then when it saves it should save as a route. It is no longer where you were it is now where you want to go. My $ .02 Dan

[bvimatelot]

Great Programme! I've just used it on a delivery from BVI to the Chesapeake and although my chart folio is not as extensive as I like, Open CPN loaded enough for a safe journey (supplemented by paper for the detailed stuff).

I find that owners love to see an actual track of what their boat has done. Using them to de-brief owners after a delivery is a lot of fun and, as someone previously mentioned, they are useful to define what went wrong or could have been done better!

Keep up the good work! Tony