Having read enough decisions and reports on collisions at sea, one thing that is often cited with being the cause of many incidents, such as groundings, is relying on "scanty" information. Taking a fix of one kind and not checking via another kind of site whether the fix is accurate.

When I was on a school ship, in the ancient past, we were sailing through the Carribean and obtained a satellite fix, on the old system. The satnav said that the satellite had low elevation, which means you shoudl question the fix it gives. About the same time, we obtained a fix using radar off a cay. The radar range and bearing put us west of the course line, while the satnav was close to the course line. Where were we? We didn't know. The officer who was supposed ot be in charge of the watch wanted to change course, but was willing to wait as I developed more information.

Looking at the chart there was a wreck on the far side of the cay. When I plotted the data from the radar fix from the wreck instead of the cay itself, the two fixes agreed. So, then the question was what was the radar fix off of? I located the correct copy of Sailing Directions which stated the wreck was often a better radar fix than the cay. We still didn't rely on any of this information, and we sought additional information. When we got it, a radar fix off the wreck and the sanav fix appeared to be correct. If we had changed course, the course change would have brought us nearer the cay and the shallower water around it.

If more information is available, get it and use it. Do not rely on scanty information.