|Quoting dreadnought (Reply 244):|
Quoting Flighty (Reply 243):
Question: don't they have good sonar to explore close quarters such as this? Such a big ship should have audible collision warnings right ?!
Sure they have all sorts of sonar. The ship was only 5 years old. Last night on Fox News they had a segment showing a training simulator for a cruise ship, supposedly equipped pretty much the same as the Concordia. Just like an airliner simulator, but a hell of a lot bigger. A crew was practicing entering a harbor, and for the benefit of the cameras, the test supervisor suddenly introduced a squall into the simulation, which promptly caused the ship to ground. Pretty interesting.
Dreadnought, you are partially correct... As I noted earlier, because it is a practically brand new cruise ship the depth-sounding equipment aboard HAD to be decent, however most commercial vessels use what basically is a fish finder, except slightly more sophisticated. one ping goes straight down from wherever the 'ducer is mounted, hits something more solid then seawater, and rebounds. each "ping" gives an averaged depth over the footprint of that ping. (In shallow waters, this footprint will be smaller, allowing for a more precise reading than in deeper waters,unless the seabed under the 'ducer is at a steep angle, then the midpoint will be what you read on the bridge.
Now, on a ship as large as this they may have 2 or 3 different 'ducers, though each would have to be at a different frequency that did not interfere with the other 'ducers.
The part that I said was partly correct is that while yes, there are many much more expensive (and more accurate) sonar systems out there that can make dynamite graphics of the seabed in 1m resolution, you need a dedicated staff aboard processing the data to interpret the data correctly - AND
you need to be going under 10 knots generally speaking.
I have heard of, and seen, singlebeam "fish finder" data from Federal vessels transiting the open ocean with their sonar turned on, but not being monitored and not going survey speed, and the data is extremely noisy - to the point you would almost prefer to go back out and resurvey the area vs trying to clean the data correctly.
Long story short, I highly doubt that any cruise ship would spend the money, time and energy to get a more accurate sonar when sll of the above trade-offs and realities kick in.
Oh, and in multibeam data, you can consider yourself lucky to process through a set of data in the time it took you to collect that data - ie 1:1 ration survey time:data processing time.
Sorry if this was too complex/long winded!
"There weren't a ton of gnats there where a ton of gnats and their families as well!"