Are Your Nautical Charts Accurate?

Some of the data on NOAA charts date back 150 years. A typical chart might have data that dates back to 1890 with the depths and positions taken by a lead line and  sextant;  while some  areas  are from a full-coverage echo sounders just taken  in the last few years.

NOAA is starting to indicate on charts when the position and depth data was taken and the expected accuracy,  so boaters will better understand the accuracy  of the chart and NOAA has been showing the date the depth was last surveyed on some charts for several years.

It may seem an impossibility to keep all the thousands of nautical charts up to date, so  exactly how would we know how out of date a chart is?

The Coast Survey is gradually presenting a new feature called the zone of confidence, or “ZOC” box and  will replace the source diagram that is currently used on large-scale charts. Source diagrams, and the improved ZOC, can help mariners assess the validity of hydrographic data and the rate the associated level of risk to navigation in a particular area.

The first charts to show the new ZOC box were  18622, 18682, 18754, and 11328, released on 2014,, and both source diagrams and ZOC diagrams consist of a graphic

Keeping your boat up to date is also a necessary. Protecting your boat with high quality Canvas Coverings from CMC Canvas LLC will keep your boat as “up-to-date” as your maps an equipment.