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.....................there are also many boats that have never ventured outside the Solent in the UK and suffered keel damage - simply because there are lots of shallow areas with hard seabeds that seem to attract careless skippers!
Going on from Symphony’s correct and very pertinent advice, it is unfortunate that so many boat skippers, and even professional marine navigators, put so much faith in both paper, and particularly in electronic charts, into thinking that what may be shown as a clear area ahead, is without any kind of danger that they need to be concerned about. Part of this I think may be down to the use in cars of GPS where if you are travelling in a particular direction, the cars Sat Nav will show that you are driving on the correct side of the road. It’s nothing more than an illusion, because the programming simply assumes that you know what you are doing and automatically puts you on the correct side of the road irrespective of whether you are there or not.
Electronic charts in almost all cases are nothing more than electronic versions of paper charts from which those electronic charts have been copied, along with both all of their attributes as well as all of their faults. Because GPS very frequently provides ones position to several decimal places, people start to think along the lines of “Wow, this is so accurate.” Unfortunately, while your position shown may possibly be accurate, it is just so much bullshxxx to assume that the chart has been surveyed to an equal standard of accuracy. Chapters 1, and particularly chapter 2 of “The Mariners Handbook” published by the United Kingdom Hydrographic Office (UKHO) give an insight into chart accuracy which it could be worthwhile for all to read.
Most of the paper charts produced by the UKHO contain a small inset diagram showing the outline of the charted area and which also shows the dates when different parts of that area were surveyed. In very many cases those surveys date back to the mid 1800s. During those years GPS had not been invented, neither were there echo sounders, or side scan sonar, and radio communications also did not exist. As a result the degree of coverage of sea bed surveys such as those that we can have today, simply did not exist.
You might say or think that charts have been corrected up to date since those days, and yes they have, but in many instances they have not been re-surveyed. The difference is that a corrected chart means only that a number of small corrections have been applied up to the present date, but it does not mean that everything that currently exists on an area of sea bed is faithfully shown unless there is a statement somewhere on the chart that full sea floor coverage has been achieved.
The point of all of the foregoing is that charts, whether paper or electronic, should, as stated in The Mariners Handbook “be used with caution.” Sometimes things exist that neither you or the hydrographers know about, and some of them could give your keel an almighty thump, so that while the kind of carelessness that Symphony mentioned is one thing, it is also pretty gung ho careless to assume that your bright shiny new chart plotter along with its brand new electronic chart is giving you all of the navigational information you might need.
Thoroughly study your charts, and try to understand their limitations, also if you see some symbol shown on your chart but which you don’t know for sure what it is because you have not looked up the meaning of that symbol in your onboard copy of “The List of Chart Symbols,” then keep well away from it.
