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Old 02-21-2017, 05:06 PM   #1
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AICW Charts

Have been wandering a couple days down the ICW, started in Savannah now in St Augustine clocked ~200 miles thus far.

For charts I use Navionics, latest Garmin and OpenCpn w/ latest NOAA.

A couple of observations -

1) There are many stretches where the charts are just plain wrong - and not just the ICW magenta line - e.g. shows we're travelling on land.

2) There is significant error in terms of shoaling, which I understand is hard to keep updated (see below).

3) Vast stretches, probably at least 30 miles today were areas with not a single sounding, and probably 2/3 of that not in areas where its actually dredged.

So as you may have surmised, its my first trip in the ditch. Not a fan to be honest, in particular, if we are at a fast cruise, I'm dropping half my speed (off plane) when it gets under 10 ft and I'm doing that a lot.

My favorite point today was inside Amelia island, 25' power boat approaching keeps challenging my line, I full stop when we are 150yds away as 4' under keel. He then stops. I am like "why the hell did he stop". He calls me on the radio. "Captain I've got 2' of water here, I'm going to have to cross your bow". WHITE ON ALL CHARTS.

Anyway, Looking for some advice, it was more aggravating than I anticipated. I don't want to waste a day and dollars getting stuck in the mud.

Side Note - As a technology person, it is maddening that chart/sounding data is not even remotely good. On a given stretch of the ICW there are hundreds of sensors pinging the bottom and calculating coordinates every day that could be used to keep charts up to date with some open standards and internet connectivity (aka the cellular network)
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Old 02-21-2017, 06:08 PM   #2
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what a great idea to keep "live chart" updated on a real time basis based on actual live data....

As for the innaccuracies....do you think your location is correct and the charts are wrong...or the charts are right but your location on them is wrong ??
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Old 02-21-2017, 06:17 PM   #3
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"On a given stretch of the ICW there are hundreds of sensors pinging the bottom and calculating coordinates every day that could be used to keep charts up to date with some open standards and internet connectivity (aka the cellular network)".


Not every depth sounder is installed or calibrated correctly.


I have not noticed any inaccuracies in that area using Garmin charts and a Garmin chart plotter. I've noticed some inaccuracies in other areas, though. I would say it's the charts that are the problem. The GPS system is accurate to within ten feet most of the time.
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Old 02-21-2017, 07:25 PM   #4
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WesK agree on gps vs chart accuracy 100%. I was observing easily 50 yards off here.. in a 150 yd wide body of water. and I'm looking at at least two sometimes three different charts from different suppliers. (Garmin was worst in terms of having actual soundings)

As for collecting soundings, I understand incorporating the offset is important, but honestly, using a little math to average and throw out stuff off 2 sigmas would be lightyears ahead of an inaccurate chart. So much data being collected and effectively thrown away, a shame.
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Old 02-21-2017, 07:58 PM   #5
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Active captain can alert you to all shallow spurs. I never leave home without it.
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Old 02-21-2017, 09:36 PM   #6
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Does Active Captain run off of WIFI or Satellite?
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Old 02-22-2017, 04:47 AM   #7
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Active captain can alert you to all shallow spurs. I never leave home without it.
The web app or something mobile?


Their web app requires connectivity and does not work on tablets or phones (its built on flash... and it uses bing maps.. ugh)
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Old 02-22-2017, 06:23 AM   #8
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Does Active Captain run off of WIFI or Satellite?
Active Captain is both live on the internet and can be downloaded into computers and hand held devices with navigation software.

Ted
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Old 02-22-2017, 06:29 AM   #9
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Quote:
Originally Posted by kev_rm View Post
Have been wandering a couple days down the ICW, started in Savannah now in St Augustine clocked ~200 miles thus far.

For charts I use Navionics, latest Garmin and OpenCpn w/ latest NOAA.

A couple of observations -

1) There are many stretches where the charts are just plain wrong - and not just the ICW magenta line - e.g. shows we're travelling on land.

2) There is significant error in terms of shoaling, which I understand is hard to keep updated (see below).

3) Vast stretches, probably at least 30 miles today were areas with not a single sounding, and probably 2/3 of that not in areas where its actually dredged.

So as you may have surmised, its my first trip in the ditch. Not a fan to be honest, in particular, if we are at a fast cruise, I'm dropping half my speed (off plane) when it gets under 10 ft and I'm doing that a lot.

My favorite point today was inside Amelia island, 25' power boat approaching keeps challenging my line, I full stop when we are 150yds away as 4' under keel. He then stops. I am like "why the hell did he stop". He calls me on the radio. "Captain I've got 2' of water here, I'm going to have to cross your bow". WHITE ON ALL CHARTS.

Anyway, Looking for some advice, it was more aggravating than I anticipated. I don't want to waste a day and dollars getting stuck in the mud.

Side Note - As a technology person, it is maddening that chart/sounding data is not even remotely good. On a given stretch of the ICW there are hundreds of sensors pinging the bottom and calculating coordinates every day that could be used to keep charts up to date with some open standards and internet connectivity (aka the cellular network)
There are but 2 types of people who have cruise the AICW, those that have run aground and those that lie about not running aground.

Ted
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Old 02-22-2017, 06:39 AM   #10
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While far from perfect, 95% of navigating the ICW is following marks and reading the water....not the charts....while they are necessary, they are not primary tools.

Out of dozens of cruisers I have seen go aground ahead of me, most have been because they were not following the aids or didn't read best water.

Often an assistance tower gets them off relatively quickly...if you aren't a member of one...probably worth the less than $200 a year.

Plus, there are times that I wil, see a 50 foot shift or so in where the chart and reality is, then a minute or two later, right on the money...hard to say what it is caused by as I rarely look at the charts unless checking something.

There are chart recording sounders out there compiling data for the chart makers. I would guess that there is cross checking going on to toss out the percentage of readings that are outside a standard deviation for whatever reason.
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Old 02-22-2017, 07:00 AM   #11
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Idea for active captin

Quote:
Originally Posted by O C Diver View Post
Active Captain is both live on the internet and can be downloaded into computers and hand held devices with navigation software.

Ted
You can download the ActiveCaptain app for free. If you use a compatible map on your iPad, the ActiveCaptain data will overlay on top of the chart. For example I downloaded Garman blue charts on my iPad for about $25. The ActiveCaptain data overlays on the BlueChart's, and shows me locations where other people have found problems.

I have never gotten into trouble if I follow the marks, and coordinated that with ActiveCaptain data. There are a few places where the water will not be navigable at low tide. The marks are there, but it is important to understand the depth it mean low water and to read active captain comments.

I have found after several trips up and down the ICW, that Bob423 is always right on the money. If you see a warning with serval comments, look for those By Bob423 and heed the advice.

I have learned to not read warnings on ActiveCaptain with only a couple of comments. In those cases I have learned that following the marks will keep one out of trouble. Reading warnings that have multiple comments is often essential to keeping one off the bottom (think Georgia).

While I don't think active captain is necessary to cruise the ICW, I can't imagine why anyone would not want to have it. It is a free application and the map software is free or inexpensive. People spend far more on accoutrements that add far less safety and value.

Gordon
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Old 02-22-2017, 07:09 AM   #12
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Quote:
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Does Active Captain run off of WIFI or Satellite?
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Originally Posted by kev_rm View Post
The web app or something mobile?

Their web app requires connectivity and does not work on tablets or phones (its built on flash... and it uses bing maps.. ugh)

Several Android and iOS (and probably Win10) navigation app for tablets and smartphones incorporate AC data. Sync the app occasionally when connected (WiFi or cellular) and when convenient. Use the app while underway without need for connectivity. (Assumes a GPS source for the tablet or smartphone.)

Happens we use MX Mariner (NOAA raster charts) and Plan2Nav (C-Map vector charts) on Android tablets and both serve AC data.

Another approach is a nav app that incorporates AC data and runs on a laptop (needs GPS source). The version we use of that is MaxSea TimeZero, with NOAA raster and vector charts. (Also works with C-Map and Navionics charts.) Sync AC data when connected (WiFi, in our case) and use underway without need for connectivity.

-Chris
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Old 02-22-2017, 08:19 AM   #13
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(Garmin was worst in terms of having actual soundings) .
Assuming that you are using them with a Garmin plotter, there is a setting on the plotter to display more or less detail. Set it to the highest detail and more soundings will show up.

As for all the boats with depth sounders sharing their data, that's called "crowd sourcing" and I think someone is already working on it. To me, the biggest problem (other than developing the technology to share this data) is what to do when one boat reports ten feet and another reports three feet.
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Old 02-22-2017, 08:25 AM   #14
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Following what your eyes tell you is more reliable than following the magenta line on a chart of course but there are places where the markers are too far apart to keep you out of trouble. I rely a lot on my depth sounder's low water alarm, but that's not going to help if you're cruising at 20 MPH.


I cruise at 7 knots but as soon as the alarm sounds, I throttle back to idle speed and try to figure out what is going on.


BTW: If you're cruising down the ICW (or anywhere) with one eye on the chart plotter and the other eye reading Active Captain reviews of "hazards", you're sure to go aground or worse. The most important thing is what is actually in front of you. What you see with your own eyes right now.
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Old 02-22-2017, 08:38 AM   #15
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To me, the biggest problem (other than developing the technology to share this data) is what to do when one boat reports ten feet and another reports three feet.
I see that problem periodically on active captain where the person reporting it must have been significantly out of the channel, and so for eternity there will be this nonexistent shallow spot warning. Also, there are a fair number of hazards that have been resolved, but the warning remains. Dredging is one that comes to mind. Get really tired of reading warnings that have been resolved 6 months to a year ago, that nobody else bothers to remove. Still like Active Captain in spite of the occasional false warnings.

Ted
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Old 02-22-2017, 08:39 AM   #16
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"While far from perfect, 95% of navigating the ICW is following marks and reading the water....not the charts....while they are necessary, they are not primary tools."

Absolutely. Never believe the magenta line; it is only a suggestion. Imagine the path a tug and barge would follow then attempt the same thing. Going mark to mark will only keep you on both sides of the road and remember, marks are frequently set in shallow water as shorter pilings are cheaper. This is not a science but requires skills to be learned.
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Old 02-22-2017, 08:40 AM   #17
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I don't think anyone is advocating following the magenta line. AC is another resource, like a chart, or gps or sounder. Not using a cheap resource like that makes little sense.

Here is an example of how it can help. On the backside of Camp Lejeune, an obstacle requires boats to execute an S turn. When approaching the marks, however, (both nuns) it appears that one would simply run between them. Of course that would be wrong, and those who remember to honor the marks would be OK. I have seen numerous boats run aground because they momentarily lose track of which mark should be on which side of the boat, and before Bob's your uncle they run aground. If you read active captain, you will see a warning in advance and avoid a tow.

Again, AC is not a panacea, but another tool in the tool box.

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Old 02-22-2017, 08:43 AM   #18
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I do 2 things that help with areas of concern.

One is reviewing the future days run for problem areas as noted by any cruising guide.

Two is to keep an eye out ahead on the plotter for where the deepest water might be.

The water under you isn't the problem (unless you are already aground), it is being able to turn to best water, we'll best guess water the moment the shallow alarm goes off.

Usually just chopping the throttle isn't sufficient if you keep going straight, using your momentum immediately towards deeper water often saves the day.
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Old 02-22-2017, 08:48 AM   #19
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I see that problem periodically on active captain where the person reporting it must have been significantly out of the channel, and so for eternity there will be this nonexistent shallow spot warning. Also, there are a fair number of hazards that have been resolved, but the warning remains. Dredging is one that comes to mind. Get really tired of reading warnings that have been resolved 6 months to a year ago, that nobody else bothers to remove. Still like Active Captain in spite of the occasional false warnings.

Ted
I have seen many postings on AC where "the water was only a foot under our keel" without mentioning the depth of the keel. Who is this person trying to communicate with? I'm reminded that nearly 50% of the population is below average intelligence.
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Old 02-22-2017, 10:39 AM   #20
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I just did a delivery trip from Jacksonville to the west coast of FL two weeks ago.

We stayed in the channel and never had a singe issue on a boat that draws 3'6".

Watch out for the "crossroads" in Stuart. If the sun is setting you might have a hard time seeing the water color changes. I ran hard aground there a few years back at dusk when I got slightly out of the channel.
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