Grounding of Queen Elizabeth 2 in 1992

I though this was just a issue of squat but there was also a question about the soundings. Some similarities to the Fenica, pilot onboard.Grounding of the Queen Elizabeth 2

Ripped open the bottom, something like 14 million dollars of damage.

Even with today’s full bottom-coverage sonars, can hydrographers guarantee that their surveys represent the bottom with absolute accuracy? Should mariners have unconditional confidence in the information conveyed on any nautical chart? Most mariners understand that nautical charts may not be 100% accurate – thus the term ‘prudent mariner’ comes into play. Generally, the deficiencies that mariners become aware of are the ones they can see, for example, a buoy being off station or a landmark that has been removed. It is rare that a mariner will find a depth discrepancy by grounding. There is a simple explanation for this: a prudent mariner will factor in a safety margin when using nautical charts. Prudent mariners have the wisdom to know that charted depths might not be 100% representative of the true bottom.

I went and saw her in drydock in Boston after this incident. I think it may have had a lot to do my path to becoming a merchant mariner today. Definitely left an impression on me.

You raise some interesting points, especially about laying off courses a safe distance from the potential grounding line? The Captain of Costa Concordia took similar risks in January 2012 and his vessel was a total loss killing 32 people. The British Admirality makes some relevant remarks on the subject below:

The Mariner’s handbook (British Admiralty NP 100) puts it:
"The maximum draught of vessels at the time of the survey should also be given consideration. The earlier surveyors were primarly concerned with the safe navigation of ships of their own era. (…) Draughts of 15 m were considered a maximum until 1958.
“Sidescan sonar came into general use (…) in 1973 enabling many wrecks and shoals lying between lines of soundings, which might otherwise not be located, to be detected.” (Before that time, single-beam echo-sounders were used; allowing large gaps between the survey lines, with all kinds of undetected shallow dangers.
And we must add: GPS came only in use since the nineties. Expect errors in horizontal positions, in surveys before that decade.
For navigational purposes, in most cases, it’s possible to keep a margin of safety, to err on the safe side.
The perception that nautical charts are exact instruments, will be even more stimulated with ECDIS onboard.
Charts will be digitalised, computerised, psychologically lowering the critical sense of the users, not realising that the underlying data presented may be 50 or 100 years old, and liable to many mistakes, and no longer 100% trustworthy.
A nautical chart (ECDIS or paper chart) is -at times- a dim sketch of reality.

The International Hydrographic Organisation has a long file of similar incidents, including the QE II, which can be viewed at

Cap’s from "The Art of Dredging put upa post a while back about the accuracy of charts.

It is to a large extent a perception issue. None of the Alaskan captains I sailed with implicitly trusted the chart in shoal areas. I do think that ECDIS can seduce mariners into believing that the info is more accurate and precise then it is.