Garmin to Discontinue Bahamas Explorer Data

[SparkyDorado]

from Explorer Charts:

"Big Changes in Explorer Electronic Data Availability
February 2019 introduces some changes in the sources of data being used for electronic navigation in the Bahamas. If you have come to rely on the accuracy of the Explorer chart data, this is important information for you. If you are planning a trip to the Bahamas in the near future, you may need to make some changes right now to assure that you go with the best chart data.

One of the recent developments causing a shift is that Garmin has purchased Navionics.

Garmin has announced that its new g3 marine electronics offerings will contain only Navionics data for the Bahamas. With this February 2019 issue, Garmin will no longer make Explorer Bahamas data available to its customers. The g3 will be included in the g3 accessory cards and pre-loaded chart plotters.

The Explorer data is still available on g2 accessory cards (Garmin) and earlier pre-loaded chart plotters which may be in inventory for a few more weeks. Although the release of the new g3 material has already begun, customers desiring Explorer data still have an opportunity to upgrade their g2 cards.

If you haven’t upgraded your Garmin for awhile and don’t have the g2 data, we urge you to call Garmin or visit your marine electronics store to insure that you travel to the Bahamas with the tried and true Explorer chart data.

Other avenues for insuring Explorer-only data is to go with C-Map by Navico products and its affiliates SIMRAD, LOWRANCE, and B&G. Also, chart data through MapMedia, MaxSea, Nobeltec, Standard Horizon, RosePoint Coastal Explorer, and Furuno can be trusted to use Explorer vector and raster information. If you are using RayMarine hardware, please inquire of the company as Explorer data is available but not on all units."

Press release from Lewis Offshore Ltd, 2/6/19

[billknny]

I switched from Navionics to C-Map on the basis of Explorer Chart's reputation.

That was a mistake. I have found the C-Map charts to be significantly out of date and generally less accurate compared to the Navionics and Transas charts. I have been using the three of them side by side and if I had to pick just one, it would be Transas a clear First, with Navionics a close second, and CMap/Exlplorer a very distant third.

For SURE each of them have issues, none are perfect. But the number of times I have seen misleading and problematic data on the Explorer based C-Map charts has left me wondering what magic marketing mojo they used to get the reputation they have.

[Palarran]

I love C-Map. Man are they accurate charts.

[CaptTom]

I read the whole thing, and the only thing which really stuck with me is the misuse of the word "insure" when they meant "ensure," twice.

Should I call my insurance agent to find out what "avenues for insuring Explorer-only data" I have?

Sorry, I'm in one of those moods. Carry on...

[a64pilot]

I think we will find out that the accuracy of a chart has a lot to do with where your at.
In Fl it seems that Navionics is fine, in the Bahamas, not so much

For us Navico guys this is the chart for us in the Bahamas.
I have it coming but it’s likely to be a few weeks getting to me, but I’m a little suspicious, the entire Continent on one chip? For $159?
https://www.thegpsstore.com/C-MAP-MA...ico-P3688.aspx

If you have a Zeus 2 or 3 there may be a better chip.

[Suijin]

I would think that Navionics would over time surpass Explorer charts in accuracy by virtue of the crowd sourced bathymetric sonar data, anywhere they are available. I’m assuming this is Garmin’s rationale for dropping them.

Personally I can’t stand C-map charts. The presentation layer gives me a headache.

[Pitchondesign]

Originally Posted by Suijin

I would think that Navionics would over time surpass Explorer charts in accuracy by virtue of the crowd sourced bathymetric sonar data, anywhere they are available. I’m assuming this is Garmin’s rationale for dropping them.

Personally I can’t stand C-map charts. The presentation layer gives me a headache.

Some of the crowd sourced bathymetric data is mixed with extrapolated data. The extrapolated data can be seriously in error, easily enough to put a boat on a reef. Unfortunately, there is no way to tell the difference between the two. Additionally, the crowd sourced data only goes where users boats go, which is not everwhere data is needed.

[Suijin]

That’s true. That’s why I’m talking “future”. I use the sonar charts but only in addition to other charts. I’ve also found them to be highly inaccurate in shallow water in some areas.

[Sailmonkey]

Originally Posted by a64pilot

I think we will find out that the accuracy of a chart has a lot to do with where your at.
In Fl it seems that Navionics is fine, in the Bahamas, not so much

For us Navico guys this is the chart for us in the Bahamas.
I have it coming but it’s likely to be a few weeks getting to me, but I’m a little suspicious, the entire Continent on one chip? For $159?
https://www.thegpsstore.com/C-MAP-MA...ico-P3688.aspx

If you have a Zeus 2 or 3 there may be a better chip.

When you look at the cartography sources, they’ve got the good stuff in the Bahamas. But me mention of NOAA or army corps of engineers data.

[a64pilot]

Originally Posted by Suijin

I would think that Navionics would over time surpass Explorer charts in accuracy by virtue of the crowd sourced bathymetric sonar data, anywhere they are available. I’m assuming this is Garmin’s rationale for dropping them.

Personally I can’t stand C-map charts. The presentation layer gives me a headache.

I have my depth finder offset so that it displays depth under the keel, others true depth.
How could Navionics determine which is which?
When I got my boat, it displayed a depth, but God knows what the depth was relevant to, I feel certain that it was just installed and not calibrated.
I’d suspect there may be more like that than we know.
All of this has to mess with crowd sourced depths?
Yeah I know when you get a lot of data you can average and throw out the outliers, but that requires a considerable number of data points.

[jkleins]

Originally Posted by a64pilot

I have my depth finder offset so that it displays depth under the keel, others true depth.
How could Navionics determine which is which?
When I got my boat, it displayed a depth, but God knows what the depth was relevant to, I feel certain that it was just installed and not calibrated.
I’d suspect there may be more like that than we know.
All of this has to mess with crowd sourced depths?
Yeah I know when you get a lot of data you can average and throw out the outliers, but that requires a considerable number of data points.

But if you decided to give your data to Navionics there is a setting in the app to input exactly where your depth sounder is. That is not to say that you couldn’t intentionally scam it but it is not like they are just randomly taking every depth sounder on every boat and using the readings regardless of the user settings. Although if they actually did have data on every boat they would be getting to the amount of data that could self-regulate.

[a64pilot]

Originally Posted by jkleins

But if you decided to give your data to Navionics there is a setting in the app to input exactly where your depth sounder is. That is not to say that you couldn’t intentionally scam it but it is not like they are just randomly taking every depth sounder on every boat and using the readings regardless of the user settings. Although if they actually did have data on every boat they would be getting to the amount of data that could self-regulate.

I know, I have the Navionics app, how many people do you think get that right, or even know of it?
I don’t even remember what my offset is, I have slept many times since then.

[Paul L]

Originally Posted by Pitchondesign

Some of the crowd sourced bathymetric data is mixed with extrapolated data. The extrapolated data can be seriously in error, easily enough to put a boat on a reef. Unfortunately, there is no way to tell the difference between the two. Additionally, the crowd sourced data only goes where users boats go, which is not everwhere data is needed.

As far as I can tell Navionics doesn't publish any info on how they validate, average and extrapolate the depth data. None of which is easy. You'd think that if you had 20 entries over a few years for an area that averaging them and perhaps throwing out any outliers might give you good results. But in an area where the sand banks are shifting only the later data would be valid.

[Suijin]

Originally Posted by a64pilot

I have my depth finder offset so that it displays depth under the keel, others true depth.
How could Navionics determine which is which?

I’m fairly certain Navionics scrubs the data through an algorithm that compares your data against known good data. They may, for example only use data between known good readings (in case you change settings or move it to a new boat). There are a lot of things they can do programmatically to validate and adjust data. What they actually do, who knows.

[Vasco]

User data for charts is unreliable. I prefer charts that are made by hydrographers. Not to say that I have never used sketch charts but they are used with caution and from sources that I am familiar with and trust (to a degree ).