SailNet Community banner

1 - 20 of 23 Posts

·
Registered
Joined
·
2,205 Posts
Discussion Starter #1
The magenta line on charts not the authority for navigation. Yesterday a boat was hard aground when the captain chose to follow the magenta line rather than honour the markers.

Always honour the markers and buoys.

A prudent navigator should peruse the intended track to determine if there are any problem areas beforehand as there are some glaring errors in the indicated route. For example ICW marker 58A and buoy 60 in St. Augustine the magenta line takes you over a shoal.
 

·
Registered
Joined
·
5,607 Posts
Lots of places like that on the icw. Today we went on the "wrong" side of a green can as charted. In the real world outside of our chartplotter we passed well to the correct side of that can.
 

·
Registered
Joined
·
16,466 Posts
It is like that not only on the ICW but everywhere, not only because buoys and channels are actualized more frequently but because not always the chart coincides with the GPS. GPS is very accurate, maps, that many times are yet based on old charts are not always correct regarding GPS position.

Those that have already navigated with their boats over land (at least on the plotter chart) will understand perfectly what I am talking about;)
 

·
Dirt Free
Joined
·
2,664 Posts
So everyone agrees the magenta line should not be trusted. Let me suggest that the marks are not infallible either. If we had rounded the marks in the following photos as we should have .........

Sorry guys , had several photos to illustrate the folly of blindly following marks but get a message saying "Internal Aerver Errpr" that won't let me upload.
 
  • Like
Reactions: bigdogandy

·
Registered
Joined
·
22,372 Posts
Clearly, visual reckoning and charts are mandatory.

That said, with all the cruisers that transit the ICW every year, one would think there would be a way to chart it properly. Google has a pic of everyone's house for goodness sake. Put one of those things on top of the next clorox bottle to run the thing.
 

·
Dirt Free
Joined
·
2,664 Posts
Clearly, visual reckoning and charts are mandatory.

That said, with all the cruisers that transit the ICW every year, one would think there would be a way to chart it properly. Google has a pic of everyone's house for goodness sake. Put one of those things on top of the next clorox bottle to run the thing.
the problem is that the whole thing is sand and it moves, sometimes dramatically within a few days. On our 2005 trip we had 2002 charts that were useless between Atlantic City and Manesquan but our 1971 charts were bang on.
 

·
Wandering Aimlessly
Joined
·
22,037 Posts
First of all, there is a great source of info at Salty Southeast Cruisers. Second, your eyes and your depth sounder are your friends.
 
  • Like
Reactions: JimMcGee

·
Member
Joined
·
2,449 Posts
the problem is that the whole thing is sand and it moves, sometimes dramatically within a few days. On our 2005 trip we had 2002 charts that were useless between Atlantic City and Manesquan but our 1971 charts were bang on.
These are my home waters and the channels and shoals tend to migrate. I never assume the charts are correct and I don't assume I can follow a previous route that I call up from the plotters memory unless it's very recent. These are shallow waters so I always have one eye on my depth. Probably a good strategy wherever you sail.
 

·
Banned
Joined
·
15 Posts
First of all, there is a great source of info at Salty Southeast Cruisers.
Who can possibly find what's important on that mess of a website? I search in SC and then have to wade through a bunch of individual postings to hopefully find something that matters to me. I've given up.

And what happens when you're in the Chesapeake Bay?
 

·
Registered
Joined
·
2 Posts
We just finished most of the ICW, from Norfolk to Stuart, FL. I would strongly agree that you cannot rely on the magenta line!

We relied heavily on Active Captain and found it extremely helpful through areas of low water and confusing markers. We had it running on an iPad with Garmin Bluechart mobile app at the helm along with chart plotter, charts and cruising guides.

Waiting for a deeper draft vessel to lead the way also works wonders.

Marty
 

·
Dirt Free
Joined
·
2,664 Posts
I once followed a 65 footer in my 37' trawler which drew 4'
big mistake .... he drew 3' !

Gotta love cheap TowboatUS
 

·
Registered
Joined
·
267 Posts
I've done the ICW a few times on deliveries. I've never even assumed that the magenta line was ever even close to authoritative. I'm actually surprised that it was ever a NOAA feature.

The only thing I've ever used it for was at the entrance of a large bay, when you are using a chart book, the magenta line would indicate the course to the next creek or canal on the other side of the bay. Otherwise we always just ignored it.
 

·
Registered
Joined
·
2,205 Posts
Discussion Starter #16
There are other areas in addition to large harbours where the magenta line is very handy to have such as the section from Fernandina, Fl south for about 20 miles. In these sections there are numerous off shoots and creeks as the channel meanders through the marsh lands.

If the magenta line didn't exist a prudent captain would make his own.

Most people do not subscribe to Notice to Mariners and update their charts accordingly. As a result buoys are changed and don't always agree with the chart either. The markers and buoys are the ultimate authority.
 

·
Banned
Joined
·
277 Posts
It is like that not only on the ICW but everywhere, not only because buoys and channels are actualized more frequently but because not always the chart coincides with the GPS. GPS is very accurate, maps, that many times are yet based on old charts are not always correct regarding GPS position.

Those that have already navigated with their boats over land (at least on the plotter chart) will understand perfectly what I am talking about;)
Please
What does ICW stand for.


C Maps if not pirated are very accurate so stating every where is inaccurate and if not updated in non coastal areas by C maps then you don't know how to realine using the top leading markers in harbours when you line them with your electronic charts / chart plotters. Also C maps when they licence their maps / to the competion they don't licence their full chart infomation. You will always find C maps have more information than the oppositions electronic licenced charts.

If you are using a main harbour chart or navigating a commercial shipping lane and your charts have you sailing on land then you are using a pirated version in most cases based on the free russian c map series in all probability or a copy has been given to you from a mate.

Or You have discontinued updating them probably for costs reasons if they are legit.
 

·
Dirt Free
Joined
·
2,664 Posts
ICW stands for Intracoastal Waterway

as for the rest of your post. I disagree.
 

Attachments

·
Registered
Joined
·
458 Posts
As for the ICW magenta line, there are many cases where following the line will take you on the wrong side of a buoy, with the chart being correct, but the line obviously drawn wrong.

It is like that not only on the ICW but everywhere, not only because buoys and channels are actualized more frequently but because not always the chart coincides with the GPS. GPS is very accurate, maps, that many times are yet based on old charts are not always correct regarding GPS position.

Those that have already navigated with their boats over land (at least on the plotter chart) will understand perfectly what I am talking about;)
I will agree partly with the above. However there are instances where I am not sure about GPS accuracy.
Example: I currently keep my boat at a friends dock, accessed through a 40 ft wide channel. For easy nighttime entrance I dropped waypoints along the way. They are all on land, and over 50 ft from the channel. No problem, right, I assume the chart is simply wrong and just follow waypoints. Well, depending on the day, my waypoints are sometimes spot on, and sometimes they are up to 50 ft off from where I should be!
So, what is really wrong in this case: GPS? Obviously, the WPTs did not move, but does the chart overlay differ from time to time? :confused:
 
1 - 20 of 23 Posts
Top