Navionics got it wrong.

In the PNW we have a passage called the Swinomish Channel. I haven’t used it for 20 years but did this weekend. The important thing to know about the channel is that channel markers flip sides (it’s always red right entering and red left leaving). The trick is to remember when they flip. Having not used the channel for so long I was paying attention to my plotter. I was north bound and just pass La Conner when I noticed the next 4 markers were in reality opposite of my chart plotter. Later that day I checked the chart plotter in my dingy and it showed the same error. Both chart plotters use a navionics gold chip. When I checked my Coastal Explorer it showed the makers as they truly are and when I checked navionics on my iPad it was correct as well.

Not talking about newly added or removed markers, how often have you found navionics to be wrong?

Errors?? In Beebe's book, the Barnes' reported Christmas Island was 25 miles off, using Nobeltec.

I bought a new Si-Tex plotter and it came with a Navionics chip. It consistently put me 200 or more meters off my real plot. My iPad was perfect. Si-Tex replaced it with a Cmap chip and it’s bang on.

THAT IS WHY YOU SHOULD NEVER TRUST A PLOTTER ONLY.

I just went through my collection of charts (actual NOAA paper charts) and they are all in agreement with Navionics. Apparently NOAA has decided that the tidal break is some were else in the channel and swapped the markers to updare red right as the tide returns. This change must have happened in the last 5 years as the dingy navionics chip isn’t that old.

There's an interesting discussion in Ben Ellison's PANBO website on similar issues related to Navionics software.

https://www.panbo.com/computer-assisted-groundings-bad-navionics-charts/

Personally, I wouldn't have Navionics software aboard my boat, in any way, shape, or form. Too many reports of errors of omission and commision for my taste. But of course, this is simply my opinion. YMMV.

Regards,

Pete

The important thing to remember is Navionics correct most of the time. Is "most of the time" good enough? For my arm chair it is. I'm perusing a five month cruise right now using Navionics while watching a b'ball game with my feet up in sunny AZ.

When cruising in a driving rain on a foggy day " most of the time" is not acceptable. As a toy I like it, as a tool I don't. Multiple sources rules.

tiltrider1 said:

When I checked my Coastal Explorer it showed the makers as they truly are and when I checked navionics on my iPad it was correct as well.

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What charts are you using with CE?

I find Garmin Bluecharts basemap off about 50% of the time. Not far most of the time but up to 200 ft occasionally. In the Okeechobee Waterway my boat is shown driving over land almost the whole length. The ICW, about 50-100 ft off in SWFL. Now items placed on the charts like daymarks and buoys are usually right on.

Quick sidetrack. THE MAGENTA LINE IS ONLY A SUGGESTION.

RT Firefly said:

Quick sidetrack. THE MAGENTA LINE IS ONLY A SUGGESTION.

Click to expand...

Not only the magenta line, but the dashed lines showing the dredged channels.
I'll post a few pics the next time I get back to the boat. Plenty of tracklines on the plotter consistently show the errors.

goboatnow said:

What charts are you using with CE?

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I have CE set up to update my charts every time I turn it on. It imports charts right from the NOAA website.

I did some more research and discovered that the USCG swamped the red and green markers in 2013. Apparently they were getting numerous complaints about the marks not being red right return to The Port of LaConner. USCG found they we’re unable to make the vast majority of boaters understand that red right return was tidal and had nothing to do with ports. Finally in frustration they gave up and swapped the markers. I guess they figured real mariners were smart enough to know were the channel is even if the markers are now backwards.

My dingy plotter chip is 2013 and my main plotter chip is 2011 so no surprise that they don’t show the updates.

tiltrider1 said:

I just went through my collection of charts (actual NOAA paper charts) and they are all in agreement with Navionics. Apparently NOAA has decided that the tidal break is some were else in the channel and swapped the markers to updare red right as the tide returns. This change must have happened in the last 5 years as the dingy navionics chip isn’t that old.

Click to expand...

You are correct, NOAA changed the nav aids a couple years ago to reflect the standard "red-right-returning" as you enter either end of the Swinomish Channel. La Conner is the designated port, so the nav aids "switch" at that point.

We went through the channel in the years preceding the change and always thought it odd that they stayed the same all the way through. But if you've been doing it for 20 years, I imagine the switch is strange! The "new" way seems to make more sense to the majority of boaters, especially those transiting the channel for the first time.

I will say, however, that last year we were leaving the channel to the north and Navionics showed the channel at the swing bridge to be on the wrong side of the center span! I took a screenshot and sent it to them. Haven't checked if they corrected that or not...

I don't think it's as simple as"brand X is unreliable". My plotter is Garmin Bluecharts and it's generally spot on. Except for Black River Falls harbor where it shows me about 60 from to starboard well on shore every time. My Navionics app on the tablet is spot on. OTOH, when we used that tablet on the Mississippi River I found myself being told I was in the channel when I was WAY outside - fortunately I believed my eyes more than the electronics. They're all right, until they're wrong. That's why I always keep the paper charts and binoculars close at hand.

RT Firefly said:

Quick sidetrack. THE MAGENTA LINE IS ONLY A SUGGESTION.

Click to expand...

Not on my Lowrance. The magenta line shows where I have been before, and was ok, even if it appears to run over dry land. As in fact it does for half the channel out of my marina, because it has been dredged since and I can't be bothered updating the chip just yet.

diver dave said:

Errors?? In Beebe's book, the Barnes' reported Christmas Island was 25 miles off, using Nobeltec.

Click to expand...

Dont feel bad Dave. I motored right past Bermuda. Good thing I have AA(B)A. I had to send out for a bunch more fuel.

RT Firefly said:

Quick sidetrack. THE MAGENTA LINE IS ONLY A SUGGESTION.

Click to expand...

High Wire said:

Not only the magenta line, but the dashed lines showing the dredged channels.
I'll post a few pics the next time I get back to the boat. Plenty of tracklines on the plotter consistently show the errors.

Click to expand...

We've recently found the NOAA raster corridors seem to be pretty accurate from Charleston to Portsmouth. At least we found water levels in those corridors to be as expected.

OTOH, sometimes our track presentation depended on display scale at the time. At one scale we could be definitely within the corridor, and at a larger scale we might not even be shown in the water.

Wifey was using C-Map vector charts in parallel, and some of the NOAA markers -- on both raster and vector charts -- weren't on the C-Map chart. And sometimes the track on her tablet showed us being off to one side, even if the track on the plotter (almost always NOAA raster) showed us within the corridor.

More instances of Mark I Eyeball and physical markers trump the charts.

-Chris

Hmmmm, makes you wonder how folks navigated without electronic charts

they spent a.lot more time aground....

psneeld said:

they spent a.lot more time aground....

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and or plugging up big holes.

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NOAA has a website to report nautical chart discrepancies.

https://ocsdata.ncd.noaa.gov/idrs/discrepancy.aspx?AspxAutoDetectCookieSupport=1