Cartographic anomaly?

[zoidberg]

Thinking about Angus McDoon's question below, I found myself peering at 'BA2798 - Loch Foyle to Sanda Island' - and to an anomalous marking I hadn't seen before on a Hydrographic Office chart.

Consider the purple latitudinal markings indicated, and what might appear to 'bearings overlay' - except, the numerics would seem to be reversed from that expected. A Point of Origin might be somewhere in the Sea of the Hebrides, but the annotated 'bearings' would still be reversed. And to what purpose....?

It's not a Consol Chart overlay, nor yet Decca. The 'polar' markings don't appear in my copy of BA5011 - Symbols and Abbreviations.....

Has anyone encountered this before, and able to offer an explanation?

 

[VicS]

Thinking about Angus McDoon's question below, I found myself peering at 'BA2798 - Loch Foyle to Sanda Island' - and to an anomalous marking I hadn't seen before on a Hydrographic Office chart.


It's not a Consol Chart overlay, nor yet Decca. The 'polar' markings don't appear in my copy of BA5011 - Symbols and Abbreviations.....

Has anyone encountered this before, and able to offer an explanation?

Need to get yourself a copy of the current 5011 then

They are bearings of a light off the chart limit. Somewhre along the line of bearings it should tell you to what light they refer.

See Section P ( page 39) http://www.marinedocs.co.uk/wp-cont...reviations-used-on-Admiralty-paper-Charts.pdf

 

[JumbleDuck]

They are bearings of a light off the chart limit. Somewhre along the line of bearings it should tell you to what light they refer.

Rinns of Islay, at a guess.

 

[MM5AHO]

It is clearer on chart 2798 that these are the true bearings of the Rinns of Islay light as JD says.

 

[zoidberg]

It is clearer on chart 2798 that these are the true bearings of the Rinns of Islay light as JD says.

Ta. 'Every day a schoolday'....

.....and now downloaded a 'latest copy' of BA5011.

 

[Sgeir]

The explanation is printed at the top of chart BA2798, as stated above, "True Bearings of Rhinns of Islay light".