Chart query

[cagey]

On my chart of Helford No 147 there is a dotted line at Rosemullion that becomes solid at Polwigidden Cove remains solid around the estuary until Bosahan Pt and then changes back to dotted all the way to Nare. It is between the 5m depth contour and sea/land interface. Have looked everywhere and cant find absolute answer as to what it describes, any ideas please.
Keith

 

[charles_reed]

Does it not mark the boundaries of the RSPB bird sanctuary?

Suggest you check with them or Droggie.

 

[Skyva_2]

Dotted lines (as opposed to dashed lines) can indicate danger areas like a rocky foreshore, or obstructions.

 

[bootleg]

not sure if asking the RSPB for advice on navigation is the most seaman like thing to do perhaps the UK hydrographic office www.ukho.gov.uk could help

 

[chart5011]

A dotted line as you describe is a Dangerline: 'A dangerline draws attention to a danger which would not stand out clearly enough if represented solely by its symbol (eg isolated rock) or delimits an area containing numerous dangers, through which it unsafe to navigate.'

I am guessing your chart is quite old - I have an old one also showing this dotted as you describe, I also have a later version showing the dotted line limited to a short area around Morwan Shear.

Hope this helps.

 

[Razorfish]

yes I agree. the solid line is the 2m depth contour and where it becomes ......... is an area of broken rocky ground with at least 5 charted isolated rocks.

never noticed this ..... business before - you learn something every day on the forum!

 

[cagey]

Thanks everyone have know checked with more up to date charts and the 2 metre and cluttered sea bed makes sense.
Interesting to see how chart info evolves
Keith