Maker Pro
Maker Pro

C-MAP or Raymarine woes

G

Graham Stephen

Jan 1, 1970
0
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
 
D

Dennis Pogson

Jan 1, 1970
0
Graham Stephen said:
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

Many of these "rocks" are of interest only to the officers on supertankers
drawing 10-15 metres fully laden. Does your own vessel draw such a depth?
 
G

Graham Stephen

Jan 1, 1970
0
Sorry - I failed to make my point clear - Somewhere in the digitisation the
symbol for a rock bottom that is way deeper than the draught of any
conventional surface vessel has turned in to the symbol for a rock that is
dangerous to surface navigation.

I am a sad person who corrects his paper charts, so I know that they are
slightly out of date rather than very out of date. I am still trying to
work out a policy that I can afford for updating the electronic charts.
Effectively paying two license fees for the same information irritates me.
(I am a Scot)

My patch is in a area where the legend "Unsurveyed" appears on charts.
Other parts of the chart may have been surveyed by a man, who might have
sailed under Nelson in his childhood, in small boat with a lump of lead on a
piece of string. He certainly did not have the luxury of GPS when he made
the chart so we cannot rely heavily on the accuracy of our own systems.

My charts regularly get updated with NMs where people have reported
"uncharted features". I have done this myself. There is a form H.102 for
doing it. They are not usually very significant as no master of ship would
take his ship anywhere on a 150 year old survey where there is any risk of a
surprise (hopefully!)

I am still unsure whether the problem is a C-Map or Raymarine issue - I
suspect the former. I would not risk my life on the electronic charts!!!

Graham
 
M

Marco

Jan 1, 1970
0
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
 
Top