I have 2 x E140W chartplotters interfaced on the boat. 1 has ROW charts
imbedded and 1 has N & S America. I can tell you that the charts are very detailed except for tides which are not included??? However the problem seems to be in the positioning, Currently our system is showing us up to .35 NM from our exact position determined through Radar
and dead reckoning as well as sonar soundings.
Last year we sailed south to Sandakan and stopped in Kudat which has a man made bay which is very detailed on the charts. The GPS
showed us over 1000 ft outside the bay and several hundred feet south of our actual position. On the way back north from Sandakan we again anchored in the bay and the GPS
showed us exactly wherew we actually were. As I said very detailed charts.
After much consternation and discussions with Raymarine
, they suggested that the Americans had probably programmed an error into the satlitlites due to the troubles with the N Koreans and possibly the pirates. lol
This year the GPS seems to be about worse and we would be grounded every day if we followed the GPS as we are constantly sailing over islands and shoals on the chart. I know that there is another post regarding a Garmin
system in Florida
and I can assure you that we are using the correct Datum for our charts. We also have 4 GPS antennas and the chartplotters correspond with my laptop
which has its own GPS satelitte used with separate Navionic charts. The AIS
GPS also corresponds to the rest so what is out??
Lots of dirty water
from river outflows and tidal currents so do not trust the electronic positions although as I said the charts are very detailed once you know where you actually are.