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Comment by LeifCarrotson | Hacker News Reader

Your phone has Google Maps or Apple Maps, which will alert you when there are road closures or hazards ahead, yes. It even has a list of places where there are roads, and places where there are not roads, and will not (typically) direct you to go off-roading. The behavior of VMS is like punching in a street address and having Maps tell you to go straight there as the crow flies.

It's hard to redundantly guarantee correctness, if you wanted to rely on VMS to avoid hitting the seafloor that would indeed be difficult. But come on, how hard is it to offer a highlight for the shallowest points near your course, or a warning that says "you added an extra zero here"?

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Early in the Apple Maps days I took a road trip from Minneapolis to the west coast and back. Somewhere in southern Wyoming we were headed to the front range in Summit County (west of Denver) and maps took us on what I can only describe as a dirt road up a mountain complete with wildlife of goats or whatever terrestrial creatures stirred.

But the best part? Seeing all the other users of maps along the route! Barely enough room for two cars to pass. But we had each other. Everyone would hold up their iPhone and mouth “WTF?” with wide eyes.

It would be fascinating to see what it took for people to stop and turn back.

Some of those roads are too narrow to turn around.

Reminds me of Glen Quaich which I regulary cycle. Single track road, with switch backs and 12% gradients. Often I'll cycle by besumed tourist off the main road wondering where they are. Its a public road but not cleared or gritted in the winter. A couple visiting a nearby village last week were rescued by a farmer after Google sent them along this scenic route in a snow storm.

> Your phone has Google Maps or Apple Maps, which will alert you when there are road closures or hazards ahead, yes. It even has a list of places where there are roads, and places where there are not roads, and will not (typically) direct you to go off-roading.

Google's servers have this information, compiled in real time from countless sources including direct satellite cartography and all beamed to a phone acting as little more than a user interface. Take your phone a few hundred feet below the water where it is cut off from the outside world and even the best maps in the world aren't accurate and you're going to run into a lot of things.

You could have a local copy onboard. There should be enough rack space on the boat to keep a copy that gets updated when the boat gets connected to shore data. Also for sea data, the data set would be much smaller because it hardly changes, and you don't have as many variables(i.e. live traffic, construction, etc), especially under the sea.

I don't agree that the data set would be much smaller. Maps for driving may look complicated, but they're just weighted graphs. You might have a few different data points for MLK drive like length, average traffic, speed limit, class of road, etc, and these values might even be given for each short stretch of the road, but you don't have to have any knowledge of the actual topography, and all of these values can be safely taken as rough estimates. No one is going to die if you falsely classify a stretch of road as high traffic when it's really moderate.

For a submarine, you need to know the topography of the sea floor down to meter scales. Accurate maps are few and far between, and difficult to create. Changing currents, underwater landslides, silt from rivers, sunken wreckage and even just garbage can create and move obstacles large enough for a submarine to care about in relatively short timeframes. Of course submarines can and do navigate with maps prepared ahead of time, but it's tough, and every now and then you get a run in with a sea mount.

I agree the undersea landscape can change dynamically but there is no way to do undersea data transmissions of the size required to do live updates. I guess what I meant is a sub should be able to have a more modern solution onboard because it wouldn’t take up much space on board which is a massive consideration for things like this.

Even if the data set is huge, you should be able to fit the system and a redundant system in a full rack. When I was on a surface ship, our entire nav system fit on a single server with an additional server as a backup. Our system could be updated live because we had internet on board. Subs don’t have this luxury so they would need the full dataset on board.

(Opinions are my own)

You can actually operate Google maps with no internet connection: https://support.google.com/maps/answer/6291838?hl=en&co=GENI...

This will not have the same feature set but the UI will let you know that this is operating with reduced data. Route planning is still very good offline. I had to use this feature because for some time part of my route home had no cell signal.

I use this hiking sometimes. Not as good as GPS obviously, but better than AllTrails.

> Not as good as GPS obviously

It is GPS.

You might be misunderstanding. They parent may be saying that they download the maps and just search for a road and use it like a paper map.

Also, "GPS" in the United States colloquially refers what people in the UK would call "sat-nav" not to the satellites + protocol (what it actually means on paper).

> You might be misunderstanding. They parent may be saying that they download the maps and just search for a road and use it like a paper map.

Maybe? When hiking it makes some sense to forego GPS to save battery power. I didn't consider that possibility when I commented earlier, but in my defense the context of the comment is using maps without an internet connection.

> Also, "GPS" in the United States colloquially refers what people in the UK would call "sat-nav"

Sure, but sat-nav doesn't require internet service...

doesn't that still allow GPS communication?

It certainly does. Pure inertial guidance with smartphone sensors is garbage. I must say I'm a bit startled by how many people evidently think that GPS is an internet service...

Cell phones use A-GPS which relies on cellular data service. It allows for faster position fixes using base station signals. Of course a cell phone with a view of the sky can still get a position fix entirely from satellites, it just takes a little longer.

I've used GPS navigation extensively on my phone with no internet service; I drove clear across Canada with my simcard pulled, it works fine.

If I had to guess, these conflations of cell service with GPS are a product of misleading UX created by Google. OSMAnd makes the nature of GPS clear, displaying a count of satellites it's managed to hear. Enough satellites to get a location good enough for car navigation almost always takes less than a minute.

There are some other aspects of locations that use downloaded data, like building heights, wifi base station locations, etc.

Yes, it does but knowing where you are isn't the problem for these systems it seems. Also, you can get very far with inertial tracking: https://en.wikipedia.org/wiki/Inertial_navigation_system

Couple that with point clouds of the sea floor, manual input from humans, etc, you can do quite well.

Knowing where you are is very much the problem. If you are 100 meters east of where you think you are, the sea mount you think you are 100 meters west of is a big problem. Inertial navigation systems tell you your position relative to your last "known" location, but if that last point was inaccurate, or if too much error has accumulated since the last point, you can be significantly off from where you think you are.

Couple this with the lack of good maps of certain sections of the sea floor, and human error, and a collision every couple of years becomes probable.

This isn't what the website is referring to. You should go read it. They literally give an example of a sailor entering a proposed navigation track into VMS which is unsafe (it hits the seabed or comes close based on static data available to VMS) and yet VMS still doesn't warn about the unsafe track.

No one, least of all a qualified submarine officer, is proposing that VMS should somehow get a real-time feed of oceanographic surveys while deployed on active operations.

Yeah, and if I steer into a brick wall my phone doesn't tell me anything either.

I read the article, and I agree VMS could likely be better, but the map apps on your phone are not examples of navigation systems that have fixed VMS' problems.

The author isn't suggesting to replace VMS with Google Maps.

The author is suggesting to implement what VMS is meant to do with an application with the same level of usability, reliability and performance as what was put into Google Maps, and Apple Maps, or frankly any reasonably-popular mobile app that doesn't involve gaming.

Do not confuse VMS with a turn-by-turn navigation system, that isn't what it does, or what an actually-usable replacement would have to do. VMS is meant to help plan a voyage and ensure you're safely executing to that plan in transit, and it doesn't do a good job of that for all the reasons the author provided.

I do offline navigation with OSMAnd all the time; you have to think ahead a little (download the relevant maps when you have a connection available) but it works great. I even found out about a construction project under my home before the official notification.

Yeah but would you let it guide you while blindfolded?

I've relied on it to keep me on the road in low visibility, which admittedly may not have been entirely wise.

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