PAPER NAUTICAL CHARTS VS DIGITAL CHARTS

I am going to appear a little backward to you with a column on paper nautical charts. The digital world is taking up more and more space and I understand you because a digital screen where you can enlarge or reduce the scale is very useful when you have limited space to lay out a paper nautical chart in A0 format in a sailboat or a motor boat. To alleviate the drawbacks of the paper size and its permeability, publishers are starting to print on paper that is water resistant, erasable and less likely to break due to frequent use. Now we have many advanced nautical charts for navigating in the oceans, like British Admiralty charts.

The electronic navigation chart does not have the disadvantages listed for paper charts. On the other hand, do you know the date of the last update of your digital map or can you find it easily? Is your digital map updated? Congratulations! Another question: who made the update and from what organization’s data?

The Merchant Shipping Act is clear:

The official paper nautical charts and documents published by the Canadian Hydrographic Service ( www.cartes.gc.ca ) are the only legal documents for navigation on water bodies in Canada ; It should be noted that manufacturers use data from the Canadian Hydrographic Service to construct their electronic navigation charts. The law allows the addition of an electronic navigation chart provided that the up-to-date paper charts are on board. This law will be amended only when the legislator is certain that the digital document will be less faulty than its paper version or that other organizations will have precise data and of comparable quality to that of the Canadian Hydrographic Service.

Here are a few examples of faults:

1) shutdown of the operation of the application or of the computer where the electronic navigation card is housed;
2) generalized electrical failure on the boat;
3) failure or malfunction of the positioning system on board the boat;
4) failure or malfunction of the positioning system. Do you have an efficient back-up plan?

The paper chart and nautical documents are free from these faults and with a few navigation instruments, we can take stock and put them on a paper chart.

CHS raster map viewer using free OpenCPN navigation software.

Manufacturers of electronic navigational charts increasingly use data and updates provided by the Canadian Hydrographic Service. A check on the website www.cartes.gc.ca ensures that the updates are incorporated into the version of the map offered.

Some manufacturers offer mariners to update their electronic charts themselves. You should be aware that these updates are made from tidal predictions that can deviate from 0.3 to 0.4 m from reality to reach up to 1.5 m during very high or very low atmospheric pressures. Then, you must know the height of the GPS antenna and the depth of the depth sounder in relation to the surface of the water. We must also avoid taking a sounding at the bottom or at the crest of a wave, otherwise we can induce a bias in the depths and compromise our safety and that of our passengers.

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