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