Page 11 of 19 pages
EN
3.3
CPA Function
A "Collision" means more precise in technical terms: CPA "Closest Point
of Approach". The easyWATCHBOX devices have a built-in feature,
which calculates the CPA with every received AIS target.
You can now set a safety radius (around your ship). If a target ship en-
ters your safety radius (in this example 500 m) within the stated time
limit (here 30 minutes) the CPA alarm occurs.
You may change the radius and the time by the "Settings" buttons.
Possible safety radius: 100 m, 200 m and 500 m.
Possible time limits: 5 min, 15 min and 30 min.
Some recommendations:
If you are sailing in areas with very few vessels around, you should in-
crease the radius and time.
A radius of 100 m and a time of 5 minutes is suitable in high traffic ar-
eas. Here you get a lot of collision alarms, so you can reduce the alarm
to those, which are indeed critical.
CAUTION:
When the easyWATCHBOX gives a collision alarm, double check the situ-
ation on the chart plotter for identifying the dangerous vessel.
Only vessels, which do have a properly working AIS aboard, are able to
trigger the CPA alert in the easyWATCHBOX!!
However a good seamanship and keeping a lookout
is always essential!
