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Old 11-06-2024, 19:30   #1
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Round the Cans Waypoint Following

I don't have a plotter above decks but I have Open CPN on a laptop down below.

We sail short round the cans courses - can I select the course in OpenCPN and have it automatically change the current waypoint (then pushed out over NMEA0183) as we round the relevant mark?

Main aim is to avoid having to go below.

I have done some searches but other than an old feature request I can't see explicit documentation for this.

Thanks....
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Old 11-06-2024, 21:54   #2
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Re: Round the Cans Waypoint Following

https://opencpn.org/wiki/dokuwiki/do...te_autopilot&s[]=advance%20route%20waypoint%20on%20arrival%20only
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Old 12-06-2024, 03:20   #3
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Re: Round the Cans Waypoint Following

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Originally Posted by mdibella View Post
https://opencpn.org/wiki/dokuwiki/do...te_autopilot&s[]=advance%20route%20waypoint%20on%20arrival%20only
Thank you - that is excellent.
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Old 15-06-2024, 06:37   #4
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Re: Round the Cans Waypoint Following

@BlackSwan6336 if you are racing round the cans, you might have the issue of which cans in which order not being known long in advance. Some clubs announce the course shortly before the ten minute gun.

I wrote a JavaScript for this situation - BuildRaceCourses.
See Appendix F in the JavaScript plugin User Guide.
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Old 17-06-2024, 04:06   #5
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Re: Round the Cans Waypoint Following

For racing you might want to have a route that will connect to itself, in a circle effectively, where the next waypoint is attached to the first waypoint. OpenCPN does do this and there is an example shown in the manual under Use Routes. OpenCPN also jumps to the next waypoint dependent on the near waypoint setting when the route is in active mode with the Console showing.
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Old 24-06-2024, 15:25   #6
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Re: Round the Cans Waypoint Following

What about the scenario when you are at the helm, and you just want to leverage the on-deck displays (in my case, B&G Triton) to see the bearing to the next waypoint, the XTE and the ETA? OpenCPN is running on a below-deck laptop.

Perhaps you don't want to use the A/P, or you are not allowed to use it (racing rules in effect), or the A/P is out-of-service. Whether or not you engage the A/P, it seems it should be possible to visualize the BTW, XTE and ETA on the on-deck displays.

The OpenCPN documentation does not seem to cover this use case. The "Route to Autopilot" page indicates it sends the RMB and APB sentences to "the autopilot". Technically, it would be more accurate to state OpenCPN is sending these sentences to the NMEA bus, and any device (including the autopilot) should be able to consume these sentences. What is the NMEA sentence (or PGN) that B&G/Raymarine/Garmin repeaters use to show the BTW? Can OpenCPN generate these sentences? I'm guessing the on-deck displays need to receive PGN 129284 Navigation data and PGN 129283 - Cross Track Error.
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Old 24-06-2024, 15:33   #7
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Re: Round the Cans Waypoint Following

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Originally Posted by srosset View Post
What about the scenario when you are at the helm, and you just want to leverage the on-deck displays (in my case, B&G Triton) to see the bearing to the next waypoint, the XTE and the ETA? OpenCPN is running on a below-deck laptop.

Perhaps you don't want to use the A/P, or you are not allowed to use it (racing rules in effect), or the A/P is out-of-service. Whether or not you engage the A/P, it seems it should be possible to visualize the BTW, XTE and ETA on the on-deck displays.

The OpenCPN documentation does not seem to cover this use case. The "Route to Autopilot" page indicates it sends the RMB and APB sentences to "the autopilot". Technically, it would be more accurate to state OpenCPN is sending these sentences to the NMEA bus, and any device (including the autopilot) should be able to consume these sentences. What is the NMEA sentence (or PGN) that B&G/Raymarine/Garmin repeaters use to show the BTW? Can OpenCPN generate these sentences?
Good question, but trivial to find out the answer. I'm running SignalK as the mediator so I'll test it before I try and do it on the boat. Watch this space...
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Old 24-06-2024, 15:36   #8
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Re: Round the Cans Waypoint Following

Quote:
Originally Posted by srosset View Post
What about the scenario when you are at the helm, and you just want to leverage the on-deck displays (in my case, B&G Triton) to see the bearing to the next waypoint, the XTE and the ETA? OpenCPN is running on a below-deck laptop.

Perhaps you don't want to use the A/P, or you are not allowed to use it (racing rules in effect), or the A/P is out-of-service. Whether or not you engage the A/P, it seems it should be possible to visualize the BTW, XTE and ETA on the on-deck displays.

The OpenCPN documentation does not seem to cover this use case. The "Route to Autopilot" page indicates it sends the RMB and APB sentences to "the autopilot". Technically, it would be more accurate to state OpenCPN is sending these sentences to the NMEA bus, and any device (including the autopilot) should be able to consume these sentences. What is the NMEA sentence (or PGN) that B&G/Raymarine/Garmin repeaters use to show the BTW? Can OpenCPN generate these sentences?
The correct NMEA0183 sentences are RMB and APB that opencpn sends when you activate a route. Those sentences do not activate the AP, but only provide BTW, DTW, and XTE for any device (but usually an autopilot) to use. I do not believe that ETA is included, it would be up to the device to calculate that itself based on available information (which would also need to include COG and SOG).

I use this exactly as you say, displayed on my autopilot display, even if I am not using the autopilot. There is no reason that any other instrument couldn't use it as long as that instrument knows what those sentences are. So, check that your Triton can display those fields.

OpenCPN does *not* provide the same information on the NMEA2000 bus (but some autopilot plugins do). However, if you connect OpenCPN to the NMEA2000 bus via a NMEA0183-NMEA2000 converter/gateway, those sentences are converted to the correct PGNs, which is how my boat is setup.
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Old 24-06-2024, 15:49   #9
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Re: Round the Cans Waypoint Following

Quote:
What is the NMEA sentence (or PGN) that B&G/Raymarine/Garmin repeaters use to show the BTW? Can OpenCPN generate these sentences?
For NMEA 0183 the APB sentence. There is also BOD and BWC, however I don't think OpenCPN generates these. In anycase these are just subsets of the data contained in the APB sentence.

For NMEA 2000, PGN, 129284 for navigation data (pretty much equivalent to APB) and 129283 for XTE.

OpenCPN does generate APB sentences when a route or waypoint is active. Other than NMEA 2000 network management functions (PGN 60928, address claim, PGN 126996, Product Information) it does not generate any NMEA 2000 PGN's.

The TwoCan plugin does convert NMEA 0183 sentences to NMEA 2000 or you may want to avail yourself of the NMEA 2000 features in the new version of the Javascript plugin.
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Old 24-06-2024, 16:59   #10
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Re: Round the Cans Waypoint Following

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you may want to avail yourself of the NMEA 2000 features in the new version of the Javascript plugin.
Thanks, I will take a look at that. I compiled and installed HEAD of master OpenCPN yesterday. I saw it does support NMEA 2000 output, though I was expecting PGN output filters similar to what is done for NMEA 0183 sentence filters. I'm a bit unclear how the lack of filters wouldn't create a loop or cause unecessary load on the bus.
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Old 25-06-2024, 01:10   #11
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Re: Round the Cans Waypoint Following

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I'm a bit unclear how the lack of filters wouldn't create a loop or cause unnecessary load on the bus.
OpenCPN handles NMEA 2000 quite differently to how it handled NMEA 0183.

In addition core OpenCPN only parses a very small subset of NMEA 2000 PGN's, essentially those related to NMEA 2000 network management, position and AIS. Others related to depth, speed, wind, autopilot, navigation, engine, fluid levels, electrical etc. are handled by respective plugins.

As navigation related NMEA 0183 data (APB, RMB, XTE) is generated at a rate of 1Hz, conversion of these by a plugin to their NMEA 2000 equivalents at the same rate would be unnoticeable on the NMEA 2000 network.
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Old 28-06-2024, 09:24   #12
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Re: Round the Cans Waypoint Following

We use Navionics on an IPAD equipped with GPS as our backup. This works very well and is immune to most disasters. Our Simrad at the nav below has an auxiliary remote monitor on deck. If yours is capable look for the units sold for over the road trucks and other vehicles. For a long time we had a handheld plotter that was very good on deck, yet another back up.
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Old 29-06-2024, 06:52   #13
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Re: Round the Cans Waypoint Following

Please, this forum is about OpenCPN.

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We use Navionics...
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Old 03-07-2024, 05:52   #14
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Re: Round the Cans Waypoint Following

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...as our backup.
You stopped at Navionics, didn't you?
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