7 ms·

But doesn't virtually anyone have a smartphone now? A phone + powerbank should suffice. And most likely there would be additional people on board in case someo

But doesn't virtually anyone have a smartphone now? A phone + powerbank should suffice. And most likely there would be additional people on board in case someone's phone stops working (e.g. dropped into the sea). And if I were to navigate in a foggy/stormy day by myself, I'd at least carry an additional phone. And if there was so much fog that would affect GPS signals, how can lighthouse lights be seen anyway? I'm not a sailor or anything, just trying to understand why this can't be done and why lighthouses are still needed.

throwaway0a5e 4y ago
There are a lot of sea states and weather conditions in which it's inappropriate and somewhat futile to whip out a smart phone on anything that doesn't have a fully enclosed bridge. Marker buoys are your friend in those situations.
TameAntelope 4y ago
And what signal to download the updated weather data?
- can16358p 4y ago
  Your comment is completely irrelevant to my comment as I'm not commenting anything related to getting weather data.
  - TameAntelope 4y ago
    Then your comment is incomplete! You would need accurate weather data to use your cell phone successfully to navigate in the night time during weather where a lighthouse is of most importance.
_moof 4y ago
Fog doesn't affect GPS. GPS is just not 100% reliable (ask me how I know) or necessarily even the best navaid for every situation. Even aircraft go visual for the last few hundred feet. (Or if they're doing autoland, it's with a purpose-built ground-based system, not GPS.) Speaking more generally it's just very risky to put all your eggs into one basket when it comes to navigation. It's so difficult to impress upon the new generation of navigators that they are guaranteed to be completely screwed at least once in their lives if they don't learn something other than GPS.
- mortenlarsen 4y ago
  > GPS is just not 100% reliable (ask me how I know) How to you know?
  - tawm 4y ago
    As OP hasn't replied yet, I'll take the liberty. The biggest issue is interference (jamming) by malicious actors. This is especially common in the eastern Mediterranean [1]. Earlier this year there have also been reports of interference on Finland's border with Russia [2]. Of course one could imagine other scenarios where GPS might become inaccurate or unavailable on a larger scale, such as an attack on the satellites themselves. [1] https://safety4sea.com/us-marad-gps-interference-incidents-reported-in-the-eastern-mediterranean-sea/ https://safety4sea.com/us-marad-gps-interference-incidents-r... [2] https://www.traficom.fi/en/news/unusual-amount-reports-about-gps-interference-near-eastern-border-finland https://www.traficom.fi/en/news/unusual-amount-reports-about... (my guess is that _moof is a navigator with experience in the eastern med sea)
    - deepstack 4y ago
      in android, the GPS config file (some xml) file will do the trick of making the at least the GPS/Location system on the phone unreliable. Apparently each country has their own config file. Found this out when a friend used the Android bought in China in US. So no GPS is NOT reliable for critical situations, it is more a consumer connivence ATM.
      - Hitton 4y ago
        Nope. It's maps in China that are unreliable. On purpose. https://www.serviceobjects.com/blog/why-gps-coordinates-look-wrong-on-maps-of-china/ https://www.serviceobjects.com/blog/why-gps-coordinates-look...
    - mortenlarsen 4y ago
      It is not that I do not know that GPS is unreliable. But I wanted to read about what OP had experienced specifically.
gchadwick 4y ago
If you're helming a small boat in heavy weather at night having a lighthouse to steer to is significantly better than even a dedicated plotter mounted in sight of the helm, let alone a phone you have to hold. Some harbour/river entrances have a sectored light. White if you're sailing in safe water, red if you're to the left of it, green if you're to the right. Makes a fantastic navigation aid for the entrance and I'll take a setup like that over a plotter for pilotage any day.
- HPsquared 4y ago
  Sectored lights sound similar to the PAPI (Precision approach path indicator) on runways: the lights show as red or white depending if you're on the correct glide slope, too low or too high. https://en.wikipedia.org/wiki/Precision_approach_path_indicator https://en.wikipedia.org/wiki/Precision_approach_path_indica...
  - andrewaylett 4y ago
    I suspect the sectored lights came first and PAPI was inspired by them :).
  - boarnoah 4y ago
    Aircraft carriers use a red, green and yellow laser to assist with lining up for the center line of the landing deck area. Flashing to indicate how much of a correction needs to be made and turning yellow once on center line. Incidentally I couldn't find much information on this "Long range laser lineup" outside of DCS where I've heard of this first, a bit odd considering the other landing system for glide slope is fairly well documented.
    - HPsquared 4y ago
      Glide slope on a ship will be complicated by the constant pitching on the waves, so the system will need to gimbal somehow. Might as well have an active system that tracks the plane directly. Perhaps laser is also good to reduce the visible signature of the ship, the fewer lights the better. Or maybe it's just brighter for the pilots.
serf 4y ago
> But doesn't virtually anyone have a smartphone now? my elderly father sails. he has a fairly modern android smart phone, but he has absolutely no ability to use the phone outside the large 'make a phone call' button that was setup for him by family in the middle of his locked-down homescreen. He requested his phone be setup this way because he 1) has no interest to learn a how a smartphone works outside the small paradigm that he believes a phone should work and 2) he has trouble with the dexterity required to use a touch-screen and not press every button on the screen inadvertently during normal use. so , tl;dr : don't assume that having a smart phone means having the ability or know-how to use even half of the things that it's capable of. Some people have smart phones simply because they were carried into the decision by the tides of time; many would probably still be using rotary land-lines if they got their preference.
- can16358p 4y ago
  Well if he learned to use the Maps app on his phone wouldn't it help him a lot? At this point it becomes more of a business/hobby/profession-related thing to learn that would help a lot, rather than a trend or a luxury.
  - themadturk 4y ago
    But if he's an elderly sailor, that means he learned decades ago how to navigate without electronics. People have navigated for thousands of years without electronics, even without light houses. For many it's a point of pride and a pleasure that they do things like this "the old fashioned way."
    - sccxy 4y ago
      People have run aground for thousands of years without electronics, even without lighthouses... It is always amusing to listen old sea dogs after they run aground and they tell you that they have always sailed there and never had any problems. Even after that they still claim that iPads are toys and only dumb youngsters use them.
- pabs3 4y ago
jamessb 4y ago
GPS signals can be jammed [1] or spoofed [2] by terrestrial transmitters; and the satellites are controlled by the US military, who could in principle decide to deny access or degrade service. Navigational errors that could result in grounding or collisions may endanger life (and be very expensive), so it is unsafe to rely solely on GPS, even if you have redundant receivers and power supplies. [1]: https://en.wikipedia.org/wiki/Global_Positioning_System#Military https://en.wikipedia.org/wiki/Global_Positioning_System#Mili... [2]: https://en.wikipedia.org/wiki/Spoofing_attack#Global_navigation_satellite_system_spoofing https://en.wikipedia.org/wiki/Spoofing_attack#Global_navigat...
- andromeduck 4y ago
  Wouldn't directional receivers be enough to mitigate the vast majority of jamming attempts?
  - aidenn0 4y ago
    No, because GPS signals are extremely low power.
  - nradov 4y ago
    Directional receivers aren't useful for GNSS. The receiver needs at least 4 satellites in view at all times in order to maintain an accurate 3-D position fix. The latest NavStar GPS satellites do broadcast an M-code signal which is somewhat more resistant to jamming, however that technology is only available to the military and has only been partially deployed. https://www.gao.gov/products/gao-21-145 https://www.gao.gov/products/gao-21-145
- wongarsu 4y ago
  GPS could be degraded or shut off, but of course everyone noticed that weakness so we now have Russia's GLONASS, China's BDS and EU's Galileo. I don't know about the satnav units in ships, but at least modern smartphones receive and use all or most of them, no modern phone uses GPS alone. Jamming and to a lesser degree spoofing are obviously still problems
aksss 4y ago
> anyone…smartphone Sure, but coverage can suck off the coast for a variety of reasons. Also, saltwater and chaotic environments (rocking boats, loose grips, lack of places to set them down securely, annoying unlock procedures, wet touch screens, etc) mean They’re pretty annoying to use especially when things get exciting.
ezconnect 4y ago
Never trust your life and other life on a battery powered device in the middle of an ocean.
kaapipo 4y ago
GPS as a technology is incredibly accurate and precise. The problem in narrow waterways is that even with the modern chartplotters of today, the fix lags behind – sometimes even twenty seconds or so. GPS is a very important aid in determining the rough position of a vessel, but the micro-scale navigation is just so much easier to do with navigational aids (buoys, lighthouses, glitters, leading marks, etc.) > But doesn't virtually anyone have a smartphone now? Perhaps one tool amongst the others, but they have several disadvantages * You have to hold them -> one hand less available to anything useful * Even if you can figure out a way to mount a phone so that you can read it (remember to somehow accommodate charging!), the screen is still quite small -> can't be viewed at a distance Even if you somehow get all of the physical problems sorted, software problems still persist: * Where are you going to get your charts from? Certainly do not expect to not have to pay for them (a couple of hundred of dollars is not uncommon) * How are you going to view them? The solutions of the big players are quite expensive (couple hundred quid per season). Sure, the play store and such are full of some random dude's chart viewers, but are you going to trust that some random ass guy got the projection and datum conversions right? Even if they mostly did, even an error of ten meters or so could be critical. tl;dr: a good phone-based solution costs at least as much as a basic chartplotter. In addition, you have to make multiple compromises.
- sccxy 4y ago
  Navionics boating app [1] is free and 1 year daily map updates for Mediterranean Sea costs 20 eur. It is really cheap and improves safety a lot on board. Even without any navigational experience they can use this app, same can't be said about most nav systems. I am not saying you should only rely on it, but it is great addition where even passangers can use when main navigator gets injured/is sleeping/... [1]: https://www.navionics.com/fin/apps/navionics-boating https://www.navionics.com/fin/apps/navionics-boating
  - kaapipo 4y ago
    There have been multiple occasions where I would've ran aground if I had trusted Navionics' charts. Granted, I sail in Finland which has one of the rockiest waters in the world but in my situation, their products are simply inadequate for any serious use. But yeah, I could see a use case for it in some situations
lm28469 4y ago
It can be done, in a perfect world, but redundancy isn't an option when it comes to life and death situations. GPS isn't provided by God, it might be down or hacked, &c. You'd have to get phones certified for this usage for liability issues, and probably tons of other things I can't think about right now. I don't imagine a cruise ship transporting thousands of people relying on an iphone to avoid hitting a rock/the shore
- can16358p 4y ago
  I'm not saying all the big vessels to deop their navigation instruments and switch to iPhone. It's just a super convenient way to navigate around, not for mission-critical tasks (even for those it would probably work but of course not worth the risk without redundence). I mean anyone who is in a small vessel and a boat would use iPhone maps in daily life, (while keeping other ways as a backup) why not?
sccxy 4y ago
I see there are lot of downvotes for this comment, but it is not a dumb question at all. When situation is "near shored, small boat and navigate using lighthouses" then I would say smartphone would be better choice than relaying on lighthouses (light range 10+ nautical miles). There are a lot of other navigational aids usually close to shore (floating or on ground). Even tall mobile antenna towers or wind generators are more common than classical lighthouses.
relix 4y ago
Beyond what everyone else has said here, it's also just not as easy to interpret GPS location on maps. Say you're in the middle of an ocean, nothing but water everywhere around you. You're rocking on pretty good waves, going a nice 8 knots. You look at your GPS. You can see where you are right now. You can see a bit further away there's a dangerous rock which you should avoid. How do you interpret from looking at the map whether or not you're going to hit it? Your GPS might show you your bearing, but because of the waves it's oscillating 10 degrees every 5 seconds. You don't know your leeway (drift because of the wind) nor if any current might still push you into the rock. This is, of course, all calculable. But still, according to the map it's not that far away. It's hard to interpret on a feature-less ocean, and on a GPS map, whether something is 5 or 10 or 20 meters away. You're getting closer, but according to your calculations you shouldn't hit it. Hmm, did you calculate it correctly? Has the wind changed? Have the currents shifted? You look at your GPS again, the rock looks a bit closer now, but you're not sure whether that's to be expected or whether that's indicative that you might hit it. Either way, this hypothetical situation might give you a bit more of a sense on what it's like to be on a boat. Things are pretty vague, and even if your phone could say "that rock is 30 meters away", it probably won't be able to say whether you're going to hit it or not with a degree of certainty that you want to risk your life on until you're well away from it. It's hard to explain how it feels like to navigate "by instrument" on a featureless plane like this. But if there's a buoy floating, marking that rock, you can see it right there. Your human brain can easily interpret whether you're going to hit it or not, and it gives you confidence that you won't if you can see it really clearly. It's also a mark that you can use to navigate to, e.g. "I need to keep bearing X, that's approx in the direction of that lighthouse on the horizon right there" (or "I need to keep it 20 degrees off the bow"). That is much less fatiguing than steering based on a compass that is continually shifting due to the waves. I guess it's a bit similar to the difference of flying planes through clouds on instruments versus using sight. Using visuals is much easier, and much less prone to errors, which is important because if you do make a mistake it can be very dangerous indeed. Not like with a car where you can just stop or you see when you're going to run into a wall or a pond.
- londons_explore 4y ago
  Tomorrows generation of humans thinks the other way round... I can see everything easily on the GPS map, and see where I've been going, and I can steer to go wherever I like. Currents and wind and stuff don't affect me much, because I don't look at which way the boat is pointing, but which way its heading on the map (which includes the effects of currents and wind). The only annoying thing is anything that doesn't show on the map. Like floating logs, men overboard, etc. Those are a pain because I have to look out of the window and try to figure out where they are on the map! And sometimes if it's foggy I can't see those things at all!
marvin 4y ago
You are trusting your life to this low-redundancy system working. Think about that. A failure can kill you and your passengers, or cause debilitating injury. The GPS satellites themselves are a single point of failure. E.g. in northern Norway, GPS becomes unreliable or unusable whenever the Russians decide to jam it for an "exercise". Then it's whatever software you're using. Does your GPS software give you coordinates if there's some internet outage that kills your maps? Do you have backup paper maps to use those coordinates for? Do you have a compass to determine which way you're going between readings? I'll often use nothing but a GPS receiver with a map for navigating when flying or sailing. They're pretty reliable. But you bet your ass I'm not trusting my life to that single system, and will know where I am at all times and have a compass and paper map as backup in case they failed.

throwaway0a5e 4y ago

There are a lot of sea states and weather conditions in which it's inappropriate and somewhat futile to whip out a smart phone on anything that doesn't have a fully enclosed bridge. Marker buoys are your friend in those situations.

TameAntelope 4y ago

And what signal to download the updated weather data?

can16358p 4y ago
Your comment is completely irrelevant to my comment as I'm not commenting anything related to getting weather data.
- TameAntelope 4y ago
  Then your comment is incomplete! You would need accurate weather data to use your cell phone successfully to navigate in the night time during weather where a lighthouse is of most importance.

_moof 4y ago

Fog doesn't affect GPS. GPS is just not 100% reliable (ask me how I know) or necessarily even the best navaid for every situation. Even aircraft go visual for the last few hundred feet. (Or if they're doing autoland, it's with a purpose-built ground-based system, not GPS.) Speaking more generally it's just very risky to put all your eggs into one basket when it comes to navigation. It's so difficult to impress upon the new generation of navigators that they are guaranteed to be completely screwed at least once in their lives if they don't learn something other than GPS.

mortenlarsen 4y ago
> GPS is just not 100% reliable (ask me how I know) How to you know?
- tawm 4y ago
  As OP hasn't replied yet, I'll take the liberty. The biggest issue is interference (jamming) by malicious actors. This is especially common in the eastern Mediterranean [1]. Earlier this year there have also been reports of interference on Finland's border with Russia [2]. Of course one could imagine other scenarios where GPS might become inaccurate or unavailable on a larger scale, such as an attack on the satellites themselves. [1] https://safety4sea.com/us-marad-gps-interference-incidents-reported-in-the-eastern-mediterranean-sea/ https://safety4sea.com/us-marad-gps-interference-incidents-r... [2] https://www.traficom.fi/en/news/unusual-amount-reports-about-gps-interference-near-eastern-border-finland https://www.traficom.fi/en/news/unusual-amount-reports-about... (my guess is that _moof is a navigator with experience in the eastern med sea)
  - deepstack 4y ago
    in android, the GPS config file (some xml) file will do the trick of making the at least the GPS/Location system on the phone unreliable. Apparently each country has their own config file. Found this out when a friend used the Android bought in China in US. So no GPS is NOT reliable for critical situations, it is more a consumer connivence ATM.
    - Hitton 4y ago
      Nope. It's maps in China that are unreliable. On purpose. https://www.serviceobjects.com/blog/why-gps-coordinates-look-wrong-on-maps-of-china/ https://www.serviceobjects.com/blog/why-gps-coordinates-look...
  - mortenlarsen 4y ago
    It is not that I do not know that GPS is unreliable. But I wanted to read about what OP had experienced specifically.

gchadwick 4y ago

If you're helming a small boat in heavy weather at night having a lighthouse to steer to is significantly better than even a dedicated plotter mounted in sight of the helm, let alone a phone you have to hold. Some harbour/river entrances have a sectored light. White if you're sailing in safe water, red if you're to the left of it, green if you're to the right. Makes a fantastic navigation aid for the entrance and I'll take a setup like that over a plotter for pilotage any day.

HPsquared 4y ago
Sectored lights sound similar to the PAPI (Precision approach path indicator) on runways: the lights show as red or white depending if you're on the correct glide slope, too low or too high. https://en.wikipedia.org/wiki/Precision_approach_path_indicator https://en.wikipedia.org/wiki/Precision_approach_path_indica...
- andrewaylett 4y ago
  I suspect the sectored lights came first and PAPI was inspired by them :).
- boarnoah 4y ago
  Aircraft carriers use a red, green and yellow laser to assist with lining up for the center line of the landing deck area. Flashing to indicate how much of a correction needs to be made and turning yellow once on center line. Incidentally I couldn't find much information on this "Long range laser lineup" outside of DCS where I've heard of this first, a bit odd considering the other landing system for glide slope is fairly well documented.
  - HPsquared 4y ago
    Glide slope on a ship will be complicated by the constant pitching on the waves, so the system will need to gimbal somehow. Might as well have an active system that tracks the plane directly. Perhaps laser is also good to reduce the visible signature of the ship, the fewer lights the better. Or maybe it's just brighter for the pilots.

serf 4y ago

> But doesn't virtually anyone have a smartphone now? my elderly father sails. he has a fairly modern android smart phone, but he has absolutely no ability to use the phone outside the large 'make a phone call' button that was setup for him by family in the middle of his locked-down homescreen. He requested his phone be setup this way because he 1) has no interest to learn a how a smartphone works outside the small paradigm that he believes a phone should work and 2) he has trouble with the dexterity required to use a touch-screen and not press every button on the screen inadvertently during normal use. so , tl;dr : don't assume that having a smart phone means having the ability or know-how to use even half of the things that it's capable of. Some people have smart phones simply because they were carried into the decision by the tides of time; many would probably still be using rotary land-lines if they got their preference.

can16358p 4y ago
Well if he learned to use the Maps app on his phone wouldn't it help him a lot? At this point it becomes more of a business/hobby/profession-related thing to learn that would help a lot, rather than a trend or a luxury.
- themadturk 4y ago
  But if he's an elderly sailor, that means he learned decades ago how to navigate without electronics. People have navigated for thousands of years without electronics, even without light houses. For many it's a point of pride and a pleasure that they do things like this "the old fashioned way."
  - sccxy 4y ago
    People have run aground for thousands of years without electronics, even without lighthouses... It is always amusing to listen old sea dogs after they run aground and they tell you that they have always sailed there and never had any problems. Even after that they still claim that iPads are toys and only dumb youngsters use them.
pabs3 4y ago

jamessb 4y ago

GPS signals can be jammed [1] or spoofed [2] by terrestrial transmitters; and the satellites are controlled by the US military, who could in principle decide to deny access or degrade service. Navigational errors that could result in grounding or collisions may endanger life (and be very expensive), so it is unsafe to rely solely on GPS, even if you have redundant receivers and power supplies. [1]: https://en.wikipedia.org/wiki/Global_Positioning_System#Military https://en.wikipedia.org/wiki/Global_Positioning_System#Mili... [2]: https://en.wikipedia.org/wiki/Spoofing_attack#Global_navigation_satellite_system_spoofing https://en.wikipedia.org/wiki/Spoofing_attack#Global_navigat...

andromeduck 4y ago
Wouldn't directional receivers be enough to mitigate the vast majority of jamming attempts?
- aidenn0 4y ago
  No, because GPS signals are extremely low power.
- nradov 4y ago
  Directional receivers aren't useful for GNSS. The receiver needs at least 4 satellites in view at all times in order to maintain an accurate 3-D position fix. The latest NavStar GPS satellites do broadcast an M-code signal which is somewhat more resistant to jamming, however that technology is only available to the military and has only been partially deployed. https://www.gao.gov/products/gao-21-145 https://www.gao.gov/products/gao-21-145
wongarsu 4y ago
GPS could be degraded or shut off, but of course everyone noticed that weakness so we now have Russia's GLONASS, China's BDS and EU's Galileo. I don't know about the satnav units in ships, but at least modern smartphones receive and use all or most of them, no modern phone uses GPS alone. Jamming and to a lesser degree spoofing are obviously still problems

aksss 4y ago

> anyone…smartphone Sure, but coverage can suck off the coast for a variety of reasons. Also, saltwater and chaotic environments (rocking boats, loose grips, lack of places to set them down securely, annoying unlock procedures, wet touch screens, etc) mean They’re pretty annoying to use especially when things get exciting.

ezconnect 4y ago

Never trust your life and other life on a battery powered device in the middle of an ocean.

kaapipo 4y ago

GPS as a technology is incredibly accurate and precise. The problem in narrow waterways is that even with the modern chartplotters of today, the fix lags behind – sometimes even twenty seconds or so. GPS is a very important aid in determining the rough position of a vessel, but the micro-scale navigation is just so much easier to do with navigational aids (buoys, lighthouses, glitters, leading marks, etc.) > But doesn't virtually anyone have a smartphone now? Perhaps one tool amongst the others, but they have several disadvantages * You have to hold them -> one hand less available to anything useful * Even if you can figure out a way to mount a phone so that you can read it (remember to somehow accommodate charging!), the screen is still quite small -> can't be viewed at a distance Even if you somehow get all of the physical problems sorted, software problems still persist: * Where are you going to get your charts from? Certainly do not expect to not have to pay for them (a couple of hundred of dollars is not uncommon) * How are you going to view them? The solutions of the big players are quite expensive (couple hundred quid per season). Sure, the play store and such are full of some random dude's chart viewers, but are you going to trust that some random ass guy got the projection and datum conversions right? Even if they mostly did, even an error of ten meters or so could be critical. tl;dr: a good phone-based solution costs at least as much as a basic chartplotter. In addition, you have to make multiple compromises.

sccxy 4y ago
Navionics boating app [1] is free and 1 year daily map updates for Mediterranean Sea costs 20 eur. It is really cheap and improves safety a lot on board. Even without any navigational experience they can use this app, same can't be said about most nav systems. I am not saying you should only rely on it, but it is great addition where even passangers can use when main navigator gets injured/is sleeping/... [1]: https://www.navionics.com/fin/apps/navionics-boating https://www.navionics.com/fin/apps/navionics-boating
- kaapipo 4y ago
  There have been multiple occasions where I would've ran aground if I had trusted Navionics' charts. Granted, I sail in Finland which has one of the rockiest waters in the world but in my situation, their products are simply inadequate for any serious use. But yeah, I could see a use case for it in some situations

lm28469 4y ago

It can be done, in a perfect world, but redundancy isn't an option when it comes to life and death situations. GPS isn't provided by God, it might be down or hacked, &c. You'd have to get phones certified for this usage for liability issues, and probably tons of other things I can't think about right now. I don't imagine a cruise ship transporting thousands of people relying on an iphone to avoid hitting a rock/the shore

can16358p 4y ago
I'm not saying all the big vessels to deop their navigation instruments and switch to iPhone. It's just a super convenient way to navigate around, not for mission-critical tasks (even for those it would probably work but of course not worth the risk without redundence). I mean anyone who is in a small vessel and a boat would use iPhone maps in daily life, (while keeping other ways as a backup) why not?

sccxy 4y ago

I see there are lot of downvotes for this comment, but it is not a dumb question at all. When situation is "near shored, small boat and navigate using lighthouses" then I would say smartphone would be better choice than relaying on lighthouses (light range 10+ nautical miles). There are a lot of other navigational aids usually close to shore (floating or on ground). Even tall mobile antenna towers or wind generators are more common than classical lighthouses.

relix 4y ago

Beyond what everyone else has said here, it's also just not as easy to interpret GPS location on maps. Say you're in the middle of an ocean, nothing but water everywhere around you. You're rocking on pretty good waves, going a nice 8 knots. You look at your GPS. You can see where you are right now. You can see a bit further away there's a dangerous rock which you should avoid. How do you interpret from looking at the map whether or not you're going to hit it? Your GPS might show you your bearing, but because of the waves it's oscillating 10 degrees every 5 seconds. You don't know your leeway (drift because of the wind) nor if any current might still push you into the rock. This is, of course, all calculable. But still, according to the map it's not that far away. It's hard to interpret on a feature-less ocean, and on a GPS map, whether something is 5 or 10 or 20 meters away. You're getting closer, but according to your calculations you shouldn't hit it. Hmm, did you calculate it correctly? Has the wind changed? Have the currents shifted? You look at your GPS again, the rock looks a bit closer now, but you're not sure whether that's to be expected or whether that's indicative that you might hit it. Either way, this hypothetical situation might give you a bit more of a sense on what it's like to be on a boat. Things are pretty vague, and even if your phone could say "that rock is 30 meters away", it probably won't be able to say whether you're going to hit it or not with a degree of certainty that you want to risk your life on until you're well away from it. It's hard to explain how it feels like to navigate "by instrument" on a featureless plane like this. But if there's a buoy floating, marking that rock, you can see it right there. Your human brain can easily interpret whether you're going to hit it or not, and it gives you confidence that you won't if you can see it really clearly. It's also a mark that you can use to navigate to, e.g. "I need to keep bearing X, that's approx in the direction of that lighthouse on the horizon right there" (or "I need to keep it 20 degrees off the bow"). That is much less fatiguing than steering based on a compass that is continually shifting due to the waves. I guess it's a bit similar to the difference of flying planes through clouds on instruments versus using sight. Using visuals is much easier, and much less prone to errors, which is important because if you do make a mistake it can be very dangerous indeed. Not like with a car where you can just stop or you see when you're going to run into a wall or a pond.

londons_explore 4y ago
Tomorrows generation of humans thinks the other way round... I can see everything easily on the GPS map, and see where I've been going, and I can steer to go wherever I like. Currents and wind and stuff don't affect me much, because I don't look at which way the boat is pointing, but which way its heading on the map (which includes the effects of currents and wind). The only annoying thing is anything that doesn't show on the map. Like floating logs, men overboard, etc. Those are a pain because I have to look out of the window and try to figure out where they are on the map! And sometimes if it's foggy I can't see those things at all!

marvin 4y ago

You are trusting your life to this low-redundancy system working. Think about that. A failure can kill you and your passengers, or cause debilitating injury. The GPS satellites themselves are a single point of failure. E.g. in northern Norway, GPS becomes unreliable or unusable whenever the Russians decide to jam it for an "exercise". Then it's whatever software you're using. Does your GPS software give you coordinates if there's some internet outage that kills your maps? Do you have backup paper maps to use those coordinates for? Do you have a compass to determine which way you're going between readings? I'll often use nothing but a GPS receiver with a map for navigating when flying or sailing. They're pretty reliable. But you bet your ass I'm not trusting my life to that single system, and will know where I am at all times and have a compass and paper map as backup in case they failed.