Join Date: Jun 2011
Location: somewhere south of civilization
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Re: Cloud shadow on water vs Rock/coral head in water
Cloud shadows move and even though you may be moving, the cloud shadows move at a different rate, almost like cross track error. In situations where you can't tell, slow down and the above will become more apparent. Your depth sounder and chart should give you an idea if what you are looking at is even shallow enough to hit and most often it isn't, unless you are where you shouldn't be. I remember places in the Bahamas where it seemed as though we would be aground in seconds, but the water was actually 90 feet deep!
In areas without charts, like the atolls in the SoPac, we only moved during the hours when the sun allowed us to see through the water, sometimes only 4 hours a day, anchoring until the next day.
You'll get the hang of it pretty quickly, once you are doing it daily, but once in a while everyone gets fooled. Carry a good stock of Rolaids.