Boating GPS

jlh3rd said:

Not understanding .
My northeast subscription , which includes the bay, is renewed every april. Plus occasional updates.
My bay map last year showed different depths and shoaling from the previous year in various places .

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NOAA is responsible for maintaining the official marine maps. If you go to the NOAA mapping website, they list the date the map area was last surveyed and the date of any critical updates made over the past year. If I don’t see any updates noted on the NOAA site, I don’t need to update

Having said that, I run Garmin Bluechart G3 Vision on both plotters. Not under subscription services which provide “daily” updates, if available. Maps are only updated when NOAA revises a chart

Chris1956 said:

Although I have never been able to find any proof, I believe my Garmin with built-in maps is updated over the air. I say this because the main channel in Barnegat Bay is uncharted on paper maps, as it changes all the time. However, the GPS unit always has the proper buoy positions (or nearly so), even after they change over the course of a season/off season.

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Not familiar with the area, but I see the channel marked on the NOAA charts.

What built in charts are you using?

Chris1956 said:

Although I have never been able to find any proof, I believe my Garmin with built-in maps is updated over the air. I say this because the main channel in Barnegat Bay is uncharted on paper maps, as it changes all the time. However, the GPS unit always has the proper buoy positions (or nearly so), even after they change over the course of a season/off season.

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I have to use active captain which then co-ordinates with my garmin for my updates. I have to use my ipad. Mine has the built in maps...I believe.

To be clear, the area I am referring to is the channel from the ICW to Barnegat inlet. The paper charts have a note that the buoys are not marked, as they change positions often. However, on my electronic chart built into the GPS unit, the buoys are marked and quite accurate.

Chris1956 said:

To be clear, the area I am referring to is the channel from the ICW to Barnegat inlet. The paper charts have a note that the buoys are not marked, as they change positions often. However, on my electronic chart built into the GPS unit, the buoys are marked and quite accurate.

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What charts are you running?
Garmin BlueChart (raster) or Garmin Navionics (vector)?

The difference being Raster charts are eccentually scanned copies of paper charts where as Vector charts are a digital representations of data.

According to the NOAA webite, they know where a bouy is withn 30' at any given time. If the bouys moves off station, it would be reported and noted in the Local Notice to Mariner Alerts shortly there after.

Simple enough, but moving the position of a bouy on a paper chart (raster) is labor intensive and time consuming. On the other hand, moving the position of a bouy on a Vector chart would reguire a couple of key strokes (on the keyboard) and a recompile of the code, ready for inclusion in the next update of your map subscription

The internet says that my Garmin echomap chirp 74 is bluechart. It does seem to get updated over the air pretty often.


I suspect that the NOAA claim of knowing where every buoy is within 30 feet is advertising, however, I see that the buoys in Oyster Creek Channel are market on the NOAA electronic charts. They were never marked on the paper charts, as the channel is dredged every couple of years, and the buoys are moved more often than that, as shoaling occurs.