A question for any navigation / chart geeks out there

[jimbojambo]

Howdy all,

Something I've noticed on charts has been bugging me for some months now and I am sure some people in this forum can put my mind at rest so I can sleep at night (no, its not really that bad...yet).

On charts, nearly all buoys are shown leaning upwards to the right. However, the vast minority lean to the left. What's the difference?

I've consulted my trusted Admiralty 5011 but I cannot see anything about this. Attached is an example. This happens on both Admiralty and Imray charts, to the same buoys, which suggests it's clearly intentional.

Answers on a postcard!

[captnjack]

If it leaned to the right it would conflict/overlap with the 11 fathom? Or is this chart metric?

At least over on this side of the pond 99.9% lean right or are vertical unless there's a need to make it lean left so I suspect the Admiralty cartographers are following the same conventions.

[jimbojambo]

Thanks for the reply (and the chart is metric!)

That does sound like a good explanation. Although, looking at other buoys some do overlap with the sounding text... see attached.

And, I think the first one might just about fit if it leaned to the right! Would be very close though...Hmm. Could it be as simple as cartographers' discretion?

[jimbojambo]

Same buoy on a different chart - the sounding text is surely far enough away here...!

Any other ideas / theories?

[SteveHall]

I am interested to know this now....

[wiLlfish]

itt orl dipends onn wich waiy de tyde iz gowin

aV anuvver luk inn sikks howers an thay wil bee leenin de uvver waiy

[captnjack]

Ya if you couldn't tell we have very few metric charts over here!

Originally Posted by jimbojambo

Same buoy on a different chart - the sounding text is surely far enough away here...!

Any other ideas / theories?

Well since they are digital and you can zoom in/out. Perhaps the left leaning symbol is a holdover from a different scale? That is they have to make it lean left at all scales so that on some of the larger scales (more zoomed in) it doesn't conflict with the adjacent soundings. Otherwise their would be duplicative data (a left and right leaning symbol) which is shown conditionally based on chart scale. That sounds like a nightmare to ensure conformity with official charts.

In the case where it actually is right leaning and conflicting perhaps they missed the fact that at that scale (looks pretty zoomed in / pixelated) there would be a conflict? Or the original data was taken from a smaller scale chart (zoomed out) where there was no conflict and in order to ensure that it was "exactly" as legally required on the digital product they were forced to report a right leaning symbol even though it conflicts with the sounding at certain scales.

I have a feeling that the left leaning symbol in the parent data is cartographer discretion and its not making sense at different scales on the digital products.

[gtb]

Ok, so I went to ask the experts. Simon Deeves, who is the Chart Production Manager at Imray, said:

Buoys are shown on our charts leaning to the right by default. This is the standard form as indicated in the Admiralty 5011 publication. Beacons are shown standing vertically.

However, there are some instances in which the display of a buoy or beacon will conflict with other drawn data. For example, the buoy may obscure a key shoaling depth, or interfere with the display of an area limit.

On occasion, we resolve these conflicts by using a non-standard display - i.e. we may slightly rotate a beacon, exaggerate the lean of a buoy, or we may reflect the buoy through the vertical axis so that it appears left leaning rather than right.

The choice on when to do this, and which non-standard display to use, is down to the cartographer's and/or editor's discretion.

I cannot speak for the Admiralty or for any other hydrographic office, but I suspect their reasoning will be the same.

So now you know.

... but I prefer WiLlfish's answer, and will stare at my chart for a bit to see if I can see them moving at springs

[jimbojambo]

Brilliant - thanks GTB! Thanks for going to that effort too.

Captain Jack had it right too!