AIS - VHF - Open CPN

[uhtflogan]

Hi folks

I think the question is this:

If AIS functions over VHF, and you are in an area where there is poor or no VHF, could you get booted out of OpenCPN downloaded offline?

Reason for this question:

We were up in the Broughtons, BC, Canada this summer. We did not have VHF coverage from about Quadra until Blind Channel. We had to use Iridium to get a family member to text us daily the marine weather forecast to get any weather data on Johnstone, and we met any number of other people on that route this summer with the same issue.

We also had (posted on this then) an incident in which we had no VHF (probably for the first time, out of Rebecca Spit), but also no wifi / cell, and we got booted out of CMAP downloaded off line, having to rely on paper charts for next 4 days.

We had assumed the problem was CMAP, so I am taking a course now on using OpenCPN after several recommendations.

And now what I am wondering is: is it possible that we got booted out of CMAP because of the VHF issues rather than a software issue? We had two devices for redundancy, and we were booted out on both, so I am pretty confident it was not a hardware issue on the device end.

And if you can get booted out of CMAP due to limitations with AIS-VHF functionality, and if the issue is not inherently CMAP, does OpenCPN have this same vulnerability?

We picked up VHF, wifi, and cell all at the same time and were able to reconnect to our offline charts then.

Thanks for your thoughts.

[HeywoodJ]

OpenCPN runs entirely offline, you will not get ‘booted’ if you lose VHF reception, cell reception, internet or for any reason other than the device on which you are running it dies or crashes.

You will need GPS reception to get your position into OpenCPN, and that can sometimes be a brief issue in some of deep fiords in that area.

AIS will work as long as there is a signal to receive, so other vessels that are in view (radio-wise) and transmitting an AIS signal will be displayed if their signal is received.

You will need an Internet connection (or other means of transferring files you get from the wide world) to load new charts, but any charts you have previously loaded will remain available until your hardware or disk dies.

OTOH, all of this should be true of CMAP, lots of people use either/both hundreds of miles from shore where there is no cell service, no VHF shore station reception, and no internet (although that is changing).

[uhtflogan]

Thank you. That was what I needed to know to sleep well (or as well as conditions permit) on anchor.

[CaptTom]

I'm a little unclear about VHF "coverage." You'll receive, and be able to receive from, any stations within line-of-sight, and often farther. The only places where VHF is "poor" are where there's radio interference from some other transmitter. Sure, there can be places where something like a mountain blocks you from some stations, but you'll be able to communicate just fine with stations on your side of the mountain.

What I suspect here, and it's only a guess, is some reliance on shoreside AIS receiving stations which then make the data available over the internet. If that's what you're relying on, then, no, you shouldn't be sleeping well. But if it's what your friends and family are using to track your progress, then just let them know that you like to go places where nobody has bothered to install an AIS receiver

[Kettlewell]

We did not have VHF coverage from about Quadra until Blind Channel.

Even if you can't receive VHF weather radio you should be able to receive (and send) VHF radio from any vessels in your area that aren't blocked by something like a mountain, and are within range.

[sv_pelagia]

Yes, OP's original post is confusing, but SEEMS they are relying on cell data coverage. This, of course, would be a major problem for MOST of the British Columbia coast. (Only in the south - - approx Campbell River south, excluding Desolation Sound - - can one be somewhat certain of cell data.)

And yes, British Columbia coast is VERY mountainous, with many places with poor or zero VHF weather reception. (But usually medium frequency SSB contact with coast guard possible and regular forecasts on SSB for certain limited areas.)

[uhtflogan]

Hi all

Sorry if the question is confused. I may be confused, I fully accept.

What I know for sure:

We could not receive VHF weather on any of the weather stations and also when we monitored 16 did not hear any traffic. We weren't concerned about connecting with family, but if we hadn't had sat coverage up there we would not have been able to get any of the weather forecasts for Johnstone, and that was a surprise. We were using AIS as primary navigation on chart overlay.

We were not knowingly relying on cell coverage. We had cellular data on our iPhone and iPad off because otherwise it pulled too much battery power trying to find a signal, and we knew there would be no coverage up there.

We had downloaded CMAP charts offline, everything was working fine of AIS with our celluar data switched off, until it wasn't.

Looking on line, I am seeing for the first time as well that CMAP apparently suffered a major data breach in June and did implement according to their press release additional security settings. Maybe those were ongoing this summer and could have been relevant, I don't know.

What I'm hoping to understand is how OpenCPN is going to function in an area of deep fjords and very remote with apparent poor/no VHF if it's running off AIS that itself communicates via VHF.

I do wonder if Starlink might be a better option now.

I may very well not understand something so appreciate any explanations. Thanks.

[CaptTom]

Originally Posted by uhtflogan

...What I'm hoping to understand is how OpenCPN is going to function in an area of deep fjords and very remote with apparent poor/no VHF if it's running off AIS that itself communicates via VHF...

That's actually two questions.

1) OpenCPN is going to "work" just fine. It has no dependency on VHF signals. If there are AIS data available, it'll display any other vessels in range. But frankly I don't worry much about vessels on the other side of a mountain from me.

2) It does, however, depend on receiving signals from GPS satellites if you want to display your position. In some fjords you may find lower precision. That's just physics. If the signal is blocked by mountains and cliffs, you can't receive it. And if it's reflected off cliffs (or, in the city, tall buildings) that can mess up the calculations and throw off accuracy a bit, too.

None of this is unique to OpenCPN. A chart plotter can only show whatever data are available.

There seems to be a third question, which also has nothing to do with OpenCPN, about receiving weather reports. I personally I try to use VHF weather channels only as a last resort. It's just too much information, coming at me too quickly, to really get the big picture. And then you have to wait for it to cycle through all the other regional forecasts (and the other language, in Canada) before "your" forecast comes back around.

[uhtflogan]

Thank you.

I don't think there is any issue with GPS/satellite up there, only VHF. We had good sat phone coverage throughout.

I am seeing others on line https://justuseapp.com/en/app/967289...ating/problems also being booted out of CMAP and being asked to login to reboot after it crashes, so it sounds this is just a glitch with this app, and presumably OpenCPN also doesn't have the same glitch. It sounds the consensus is that it has to be either hardware or software.

On weather, how would you get weather reports remote if you have no cell, internet, no sat internet (only talk and text), or VHF? I am studying for my HF radio license, but until I pass that exam here is there another option I am missing in the interim or for redundancy? And even then, I'm not sure HF radio in a fjord is necessarily going to work better.

TIA

[sv_pelagia]

Clearly, OP has a problem with their VHF radio system.

VHF channel 16 AND VHF marine forecasts are excellent throughout Johnstone Strait.

Figure is CHS prediction of VHF coverage in BC. Not always correct, BUT absolutely there is definitely excellent coverage along Johnstone Strait - - it is too important of a commercial waterway!



And, yes, we have definitely resorted to medium and HF radio for forecasts in isolated areas w/o VHF forecast reception (yes, in deep fiords) in BC. (For examples: Princess Louisa Inlet; Kyuquot Inlet; West Coast Haida Gwaii). In these cases, we usually get official text forecasts via HAM-based email

FYI: https://sailing-pelagia.blogspot.com...itish.html?m=1


We also use our Zoleo satellite communicator for text forecasts: a friend on shore using zoleo app can send 950-character emails to us... enough for text forecast for areas we are in. (The weather info provided by Zoleo has not yet "impressed" us fot the BC coast... but it has some use.)



We use OpenCPN all the time here in BC. (Apps such as Navionics and CMA do not offer properly updated charts of BC!) As stated VHF/CELL/SAT reception is NOT an issue for OpenCPN.

Re CMAP app: please don't confuse CMAP app issues with questions about VHF reception, etc.

[uhtflogan]

Thanks. Maybe we need to check out antenna, that is a good point. But to be clear: we did not have any issue with VHF in Johnstone, either on our hardwired VHF or our mobile. As soon as we were proximate to the Strait we did get VHF fine. The issues were in the back channels and fjords.

Sounds like we are the only people having these issues, however, so that's good to understand.

My question regarding CMAP was to understand whether the issue was VHF or CMAP, and it sounds the consensus is that it is CMAP.

[Kelkara]

There certainly are some anchorages where you may not be able to receive any VHF weather forecasts. But if you consistently can't hear anything over most of the Broughtons, then maybe you should check your VHF antenna connections. The closest broadcast is only from Alert Bay (WX1?) and I've certainly been able to receive it around many of the islands, albeit a bit weak and scratchy at times.

But if you're deep in the islands or fjords, you still have to extrapolate the weather from forecasts for Johnson Strait or Queen Charlotte Strait, which may not be very relevant ... especially for winds.

If I can't get the VHF forecasts ... for the big picture of storm systems coming in from the Pacific, I may get the wefax maps off HF, or if I want something more local I'll get a spot forecast from the inreach ... or just look at the barometer and clouds.

[uhtflogan]

We had VHF issues in Thurston Bay and on the east side of Thurston until about 3/4 of the way up, Phillips Arm, east side of Hardwicke, east of West Cracroft / Chatham, back side of Gilford. I think mountains would have blocked all of those from Alert Bay.

Sounds like I need to fast track the HF as a solution. Appreciate that info.

It was unusually blowy in Johnstone for about a week in Aug, and we were trying to get the Canada marine forecast to make a decision about whether to stay put or when to make a run for it on the early morning ebb. We didn't want to be in a situation where we approached Johnstone with no weather info and had to turn around and fight the ebb back to an anchorage because it was too rough. So it was the Johnstone data we wanted but which we could not get reliably when in back channels waiting. By the time we poked our nose out into Johnstone and could pick up good signal, it didn't matter because we could see what the weather was. The weather in the back channels was quite calm when it was howling in Johnstone.

Having someone text the forecast government data on a sat phone worked fine but is pretty expensive as a solution.

[sv_pelagia]

Originally Posted by uhtflogan

Thanks. Maybe we need to check out antenna, that is a good point. But to be clear: we did not have any issue with VHF in Johnstone, either on our hardwired VHF or our mobile. As soon as we were proximate to the Strait we did get VHF fine. The issues were in the back channels and fjords.

Sounds like we are the only people having these issues, however, so that's good to understand.

- we've have good VHF weather reception in Thurston Bay area
- that area covered by Discovery Mtn transmitter
Attachment 282246

- channel 16 may not be busy in Johnstone Strait (it is even quieter north of Cape Caution)
- VTS (Vessel Traffic Services) on Johnstone Strait is on VHF 71a - - you can monitor this to see if radio working and/or contact commercial vessel
- you can always radio Canada Coast Guard on channel 83a for radio check (NOT 16!) and if no VHF weather reception, for area forecast
- in a pinch, you can call Lighthouse keepers for weather (I think IIRC on channel 82)
- in the Summer, we are on a regular morning HF HAM net for Washington up to Alaska... weather requests are often requested and given



I suggest you download (free) the CCG Radio Aids to Navigation pdf: https://www.ccg-gcc.gc.ca/publicatio...m-2023-eng.pdf

[uhtflogan]

Thanks for the info. We didn't have any issues proximate to Johnstone only in the back channels. Good to know on the Ham Net. Need to get cracking on that examination.