Yellow buoys

[Dipper]

Around here they are often associated with the military. I see on the charts that the Dodman buoys are referred to as 'A', 'B' and 'C'. The three yellow range buoys off St Alban's head are DZA, DZB and DZC so maybe there is a clue there? I assume DZ means danger zone whereas 'your' buoys aren't dangerous - unless you hit them.

 

[tillergirl]

Next question...

What is NtM ?!

If you sail in the Thames Estuary, goto http://www.crossingthethamesestuary.com/page9.html I provide a weekly (FREE) service to us in the Thames Estuary - actually covering the Wash to Dover, Boulogne to Hook of Holland - always illustrated to show positions and the features. Imray kindly allow me to copy of charts and the UKHO licensed me to repeat their data. Have a look.

 

[Yealm]

It’s sounds like no one else knows what the Dodman yellow buoys are for.

Funny that the info is not easily accessible.

 

[capnsensible]

It’s sounds like no one else knows what the Dodman yellow buoys are for.

Funny that the info is not easily accessible.

Here you go, my salty old chum. Took me and google about ten seconds!!

https://books.google.es/books?id=4U...#v=onepage&q=firing range dodman head&f=false

Always go for the easy answer. :encouragement:

 

[capnsensible]

Pilot Books.

 

[Yealm]

Here you go, my salty old chum. Took me and google about ten seconds!!

https://books.google.es/books?id=4U...#v=onepage&q=firing range dodman head&f=false

Always go for the easy answer. :encouragement:

Fantastic- top googling!
Unfortuantely the link doesn’t work for me- what does it say the buoys are for?

 

[ShinyShoe]

If you login to google it shows the content ;-)

Or go to page 156 of your paper copy of Reeds.

Or I will just tell you they are firing targets A,B,C and ships shoot at them from several miles out.

 

[Mark-1]

https://books.google.es/books?id=4U...#v=onepage&q=firing range dodman head&f=false

Ta.

:encouragement:

...and thanks to Yealm for asking the question. Interesting.

 

[rich]

On my way in to Portbail France we came upon a yellow bouy, right in the middle of the red & green bouys ,
Bye the time we worked out why it was there, we were plowing over a sand bank! As did the boat that moored up after us.

 

[Yealm]

If you login to google it shows the content ;-)

Or go to page 156 of your paper copy of Reeds.

Or I will just tell you they are firing targets A,B,C and ships shoot at them from several miles out.

Many thanks - really grateful and very interesting

 

[capnsensible]

Was gonna ask if you found it on your compooter yet?

 

[cueball]

If you sail in the Thames Estuary, goto http://www.crossingthethamesestuary.com/page9.html I provide a weekly (FREE) service to us in the Thames Estuary - actually covering the Wash to Dover, Boulogne to Hook of Holland - always illustrated to show positions and the features. Imray kindly allow me to copy of charts and the UKHO licensed me to repeat their data. Have a look.

and I can add, that this is an excellent service, used by many East coasters

 

[Yealm]

Was gonna ask if you found it on your compooter yet?

The link doesn’t work for me on my iPhone.

I’ll try my laptop and paper Reeds as soon as I can.

I wonder why the electronic charts (at least the ones I use) don’t give this info- one would think it to be incredibly simple to add, rather than putting ‘special purpose’ buoy etc. Wonder if other electronic chart manufactures give more info?

 

[Tranona]

The link doesn’t work for me on my iPhone.

I’ll try my laptop and paper Reeds as soon as I can.

I wonder why the electronic charts (at least the ones I use) don’t give this info- one would think it to be incredibly simple to add, rather than putting ‘special purpose’ buoy etc. Wonder if other electronic chart manufactures give more info?

The simple answer to that is there is much variation in the way that different chart suppliers use the data they have. They all use the same basic data from the official sources such as hydrographic offices but use it in different ways. They are mostly vector charts which construct what you see on the screen in their own way, displaying the data according either to the scale or the choice of detail level made by the user. This is one of the fundamental problems of electronic charts, but unavoidable if you want the facility to show charts and information on a small screen. As I said earlier the detail will be on the chip if it is on the source information, but the access to it for display is determined by the software. Hence the advice to also still carry up to date paper charts and MtM if you want the fullest information. Antarcticpilot who posts here is the expert on these matters and recently posted a more detailed explanation of which the above is a summary.

In practice, however, for the cautious sailor, electronic charts are sufficient, but many like myself also carry electronic raster charts which do have more detail but are nowhere as convenient to use in the way we tend to use chart plotters these days.

 

[Yealm]

The simple answer to that is there is much variation in the way that different chart suppliers use the data they have. They all use the same basic data from the official sources such as hydrographic offices but use it in different ways. They are mostly vector charts which construct what you see on the screen in their own way, displaying the data according either to the scale or the choice of detail level made by the user. This is one of the fundamental problems of electronic charts, but unavoidable if you want the facility to show charts and information on a small screen. As I said earlier the detail will be on the chip if it is on the source information, but the access to it for display is determined by the software. Hence the advice to also still carry up to date paper charts and MtM if you want the fullest information. Antarcticpilot who posts here is the expert on these matters and recently posted a more detailed explanation of which the above is a summary.

In practice, however, for the cautious sailor, electronic charts are sufficient, but many like myself also carry electronic raster charts which do have more detail but are nowhere as convenient to use in the way we tend to use chart plotters these days.

I’m sorry, I disagree.

Electronic vector charts are much better than raster and paper charts. They can be updated regularly - no sailor I know buys a complete set of paper charts every year! Electronic charts also give much more info eg real time tide heights, streams and AIS data.

The yellow buoy thing I think is an isolated issue. For some reason the full info is not being added- sure it will be in the future at some point- not a big issue but a ‘nice to have’. The yellow buoy info is also missing from my paper charts (at a quick look).

 

[GHA]

I wonder why the electronic charts (at least the ones I use) don’t give this info- one would think it to be incredibly simple to add, rather than putting ‘special purpose’ buoy etc. Wonder if other electronic chart manufactures give more info?

Visitmyharbour online admiralty Lizard Point To Berry Head doesn't seem to have any info other than the buoy names so maybe not that surprising that the vector chart info isn't there if it doesn't exist on the official raster charts?

http://www.visitmyharbour.com/charts/view.asp?c=07A4A382-251C-42F3-BDB8-BCD586E32118
(might need to be a subcriber to view)
[h=1]Lizard Point To Berry Head[/h]

 

[Mark-1]

I wonder why the electronic charts (at least the ones I use) don’t give this info- one would think it to be incredibly simple to add, rather than putting ‘special purpose’ buoy etc. Wonder if other electronic chart manufactures give more info?

There's a triangle of yellows marked as military bouys on Navionics charts:

https://webapp.navionics.com/#boating@10&key=ancqH|fb\

 

[Tranona]

I’m sorry, I disagree.

Electronic vector charts are much better than raster and paper charts. They can be updated regularly - no sailor I know buys a complete set of paper charts every year! Electronic charts also give much more info eg real time tide heights, streams and AIS data.

The yellow buoy thing I think is an isolated issue. For some reason the full info is not being added- sure it will be in the future at some point- not a big issue but a ‘nice to have’. The yellow buoy info is also missing from my paper charts (at a quick look).

Tell that to the folks who ran 2 Clipper yachts aground through relying on vactor charts.

I agree with all you say about the flexibility of vector charts - that is why they are used on chart plotters simply because you can do things that are not possible with raster charts.

However it would be foolish to ignore the downsides and see the convenience as more important than the accuracy of the information that is displayed. There is a reason why these charts come with a warning not to be used for navigation, and why the cautious amongst us treat them in a way that recognises their deficiencies. If you can find them, Tom Cunliffe wrote an excellent series of articles on this subject a few years ago in YM - well worth a read.

 

[DJE]

Electronic vector charts are much better than raster and paper charts. They can be updated regularly - no sailor I know buys a complete set of paper charts every year! Electronic charts also give much more info eg real time tide heights, streams and AIS data.

That's a can of worms you're opening there. I have electronic raster charts which I can update as often as I like and they show AIS targets. The raster/vector thing comes down to personal preference but there are regular complaints on here about poor detail displays on vector charts.

 

[dom]

Tell that to the folks who ran 2 Clipper yachts aground through relying on vactor charts.

I agree with all you say about the flexibility of vector charts - that is why they are used on chart plotters simply because you can do things that are not possible with raster charts.

However it would be foolish to ignore the downsides and see the convenience as more important than the accuracy of the information that is displayed. There is a reason why these charts come with a warning not to be used for navigation, and why the cautious amongst us treat them in a way that recognises their deficiencies. If you can find them, Tom Cunliffe wrote an excellent series of articles on this subject a few years ago in YM - well worth a read.

Agreed, and it would be nice if the vector vendors finally programmed a function whereby in a user-specified zone, every area below a user-specified depth would be displayed in say red, no matter what level of zoom is chosen.

I can think of several groundings inc. Vestas that such a facility would have helped avoid. It would be functionally easy to program, but opens legal questions with respect to the "not for navigation" exclusion which as the vendors say keeps their PI insurance way down. Pity.