Using only Navionics (app) for navigation - accuracy and dependency?

[rolf.nielsen]

I just completed my yacht master training and much as I enjoy old-school navigation, I have become used to using Navionics on ipad and phone. I always have two active units (for redundancy). The advantages are many, not least automatically updated charts so I always have the latest changes. I may or may not have paper charts onboard that cover the area I'm navigation. It's mostly coastal cruising in Denmark in areas that I'm familiar with.

I was told that Navionics and similar apps may have accuracy issues and that there have been examples of wrong positions reported in the app with up to several nautical miles difference. That can be the difference between a smooth ride and catastrophic grounding, no matter how familiar I am with the area.

Concerned by this I've been researching, but I haven't found any examples of inaccurate positions in Navionics or similar apps. It's difficult to see how the phone or ipad should suddenly pick up wrong GPS coordinates.

Has anyone here had issues like these or otherwise share the concern? I know that technically the GPS system could be disabled (in case of war etc) and I could have some kind of catastrophic electronic failure or EMP blast, but I am really hard pressed to see how any other solution could be more convenient and safe than a Navionics app with automatic updates and of course with sufficient redundancy.

As a bonus information, I'd love to learn from you out there why anyone would pay a lot of money for fixed-installation chart plotters etc in their yachts, when a Navionics app at a couple of hundred bucks can do the same without the need for fixed installations in the boat. Every time I see a commercial for a plotter I wonder.

 

[Jabs]

I use Navionics on an iPad as a back up. I have a full blown two plotter set up and use the iPad over dinner or in bed for reassurance.

Never had an issue.

I would trust it!

BUT I would have paper charts available at all times.
I have a lat/long GPS to use with paper if all else fails!

Tony

 

[duncan99210]

Tablets with a navigation app of your choice are fine. I've not had an accuracy problems o er the four or five years I've been using them as a second string to the fixed kit on the boat. There are drawbacks to them: battery life is limited, screens are not readily visible in bright sunlight, they are vulnerable to damage both physical and water. You can address some of those by work rounds but they remain work rounds not true solutions.
In addition unless you go to a good deal of trouble and expense, you can't link them all together in a relatively seamless network of radar, plotter, autopilot, depth and log speed. That's not a problem for some but a significant obstacle for others.
So for the time being I'll stick to using my integrated system for most navigation purposes but use the iPad as a planing tool and a back up if all else fails. All that said, I do like doing things with paper charts, compass and the like, just for the fun of it.

 

[RupertW]

Navionics on ipad has worked well for us for 4 years - our only other nav systems are the very basic GPS (not a chartplotter at all) and paper charts. We know we are retro and I was unsure about going for Navionics at all as I like to navigate by eye as much as possible. But it's been great and almost all the time the ipad sits on the chart table and we look around and see the world and navigate that way with glances down below.

Integration not an issue for us as I like all systems able to work with all others down - like any other hobby you choose the bits you want, and the bits where you choose to limit yourself, e.g. Sails not a fast mobo.

But on the original question - we have found the accuracy - in Med, channel and Caribbean completely accurate so far and being able to plan routes at home is the main benefit.

 

[NUTMEG]

On previous boat I had fixed cp (standard horizon) with Navionics in an iPad as a back up. That was in a wheelhouse motorsailer so sunlight and water ingress never an issue. Found I relied on the iPad over the fitted chart plotter.

I now have a little gaffer and have decided not to invest in a fixed cp, simply could not justify the cost. I have paper charts etc on board. Still to resolve the possible water problem but not a big issue as the iPad will live on a swinging bracket in the companionway.

I seriously think the end is neigh for built in chart plotters, the money they ask for them is simply a rip off, although I qualify that by stating I only daysail with occasional overnights in local waters.

 

[Gunfleet]

I’ve got to agree. I have a garmin, I have charts but I use the iPad. It’s quite well protected in an otter box too.

 

[Ningaloo]

There are currently some great deals to be had on the obsolete B&G Vulcan 7FS which has been superseded by a radar capable unit. This gives you all the additional advantages of a full plotter and the excellent SailSteer feature for little more than the cost of an iPad.
Personally I believe that plotters are the way to go in unfamiliar rock strewn archipelagos to be found in the Baltic! I would have found navigation through the Stockholm archipelago daunting if I had to rely on paper charts.
I also feel that a dedicated plotter at the helm position is worth the additional cost, although I do agree that the Navionics app may be suitable for day sailors in familiar waters and also makes a great backup for larger boats.

 

[tillergirl]

The issue is whether the GPS lat/long is coincided to the image lat/long. I discovered one such error last year (not with Navionics). The image was correct and the GPS was correct, they were just not coinciding. Fortunately that particular app displayed the lat/long of the image (showing the edge of the chart) and the cursor (reading out the GPS lat/long) showed the significant error. If I had not compared the two it would have never been spotted - until going aground! What I spotted was pure chance! Perhaps worth checking the GPS lat/long coincides with the gridding on the image!

 

[dunedin]

You will find a lot of fixed views, not necessarily logical / fact based.
Worth splitting the argument down into its logical parts

1). Navionics chart accuracy - well the version on the iPad app is likely to be at least as up to date as one on any fixed plotter, which often also uses Navionics cards. Some of us mistrust the user updated layer and switch this off. Otherwise the chart accuracy is as good as the source data - probably good in Denmark, some gaps in Scotland, and clearly some issues in certain remote parts where surveys still based on sextant and sighting lines. So no issue with using iPad App here.
2. Screen - iPad screen generally bigger than a cheap plotter, which is hugely helpful. But sometimes less visible in strong sunlight which is less helpful.
3. Ruggedness - often quoted as an issue for iPad navigation, but a fixed waterproof case at the helm is easily bought and cheaper than a fixed plotter.
4. Integration - this is where currently the fixed plotter may be stronger, with AIS and Radar overlays on the chart. But in fact our 5 year old Eur5,000 Raymarine E90Wide would support Raymarine Quantum Radar, and AIS support is limited to as at 2012 software. So in fact crossing TSS yesterday in low viz I was using plotter for navigation and the iPad as a second screen with radar and AIS data, albeit in this case Wi-fi from a small second plotter below.
5. Paper or not - can fly jumbos without paper charts, and perhaps a generation thing. Personally I like to have both but expensive and 6+ inches height of paper takes some stowing and life is not long enough to update that lot.

So assess the objective measures and make your mind up.

Incidentally for Denmark worth considering NV portfolios as quite economic and get set of charts, harbour plans and electronic chart data usable on PC, iPad and phone thrown in.

 

[dunedin]

PS. Forgot 6. GPS accuracy. No substitute for putting tablet, phone and reputable plotter side by side regularly and comparing the positions shown. May need to fiddle phone / tablet settings to show format (I prefer degrees, minutes, decimals, but not the phone standard?)
Never spotted any discrepancies yet.

 

[Ningaloo]

This sounds like a datum issue. Almost everything uses WGS84 today but if you have a configuration mismatch you can get significant errors. A few years ago my brother was navigating for me using a hand held GPS he had last used in Siberia which was configured for an old datum. Luckily I was also keeping an eye on things otherwise we might have missed the channel at St Vaast.

 

[[3889]]

I use Navionics as my primary navigation tool, often the plotter isn't turned on. I prefer a phone to a tablet as it's always in my pocket, can be used one handed and is waterproof. I carry a spare phone and a tablet on board. Zooming is so quick and easy the small screen isn't really an issue even without reading glasses. I won't be buying any more paper charts. I have never known any inaccuracy in position plotting which is precise down to the finger pontoon the boat is on.

 

[tillergirl]

This sounds like a datum issue. Almost everything uses WGS84 today but if you have a configuration mismatch you can get significant errors. A few years ago my brother was navigating for me using a hand held GPS he had last used in Siberia which was configured for an old datum. Luckily I was also keeping an eye on things otherwise we might have missed the channel at St Vaast.

It certainly wasn't a datum issue. It was an app manufacturer's error!

 

[rolf.nielsen]

Right, I'm confirmed and reassured in my usage of iPad, phone units (always with redundancy, of course!). I still don't understand folks that fork out a lot of money for fixed installations, unless of course radar and AIS overlay is worth it to them. To each their own. I'll probably always carry some paper charts, only because I - like I suspect many others here - enjoy old-school navigation and to keep those skills alive in case one day they'll be needed. Next up, sextant classes...

 

[CalicoJack]

Last week we went from St. Kats (Tower Bridge) to Chatham, using Navionics on my iPad as the main source of navigation. As we approached the barrier London VTS accused us of being on the wrong side of the river, although the track on the iPad showed us on the correct side. By the time we had passed Tilbury the visibility was so poor that you could not see from one side of the river to the other. A combination of radar and iPad meant that we found our way to the swatchway into the Medway with hardly a second thought; without I guess that we would have had to head for shallow water and anchor up as we could see nothing.