Can't you just configure your Raymarine to not display this type of info? My
C-map plotter offers numerous configuration options, including one that
won't display seabed information; there are many options that let you choose
what you want displayed.
Another possibility lies in updating your Raymarine plotter's operating
software; it may help and if not, you're getting the latest OS with new
functions anyway. Contact Paul at www.c-map.co.uk ; he may be able to tell
whether there's an update for your C-map OS (they're made by C-map not
Raymarine). You could also post your message on the forum of the same web
site.

Marco


"Graham Stephen" wrote in message
.. .
I have had a nice shiny Raymarine Chart plotter with the C-Map Cartography
for a year of so. Generally I am delighted. One issue that irritates me
seriously is the large number of rocks that have suddenly appeared in the
water that I have sailed for years.

They appear on the plotter as the + symbol (IHO 421.2 apparently) which
indicates "Underwater rock over which the depth is unknown, but is
considered dangerous to surface navigation". Cross referencing to my
paper
charts the original symbol was R which that the Nature of the Seabed is
Rock. This is not helpful and causes hairloss to the navigator.

I also come across some soundings of 60+ metres have been charted with the
+
symbol.


I am unique in suffering this problem? Is the the cartography that is
faulty or is the Raymarine unit that is causing the problem.

Any comments welcome.

Graham