Executive summary: In a little more than a month, 1/3 of the charts in the USA were updated. NOAA is keeping busy. Now you know why they require chart distributors to make updates available within 7 days of NOAA posting them. Most apps don't do that, SEAiq makes them available immediately and makes it easy to download them.
Our users in the USA are no doubt surprised by how often NOAA updates their charts. We were. For most users, every time you have SEAiq USA or Free check with NOAA, there are probably updates for the regions you are interested in.
We started downloading the NOAA catalogs daily and analyzing them to get more information on the updates. This is an ongoing project and we'll keep digging into the information and tell you about what we learn, as well as use it to help improve our apps.
First, some background numbers. There were 938 charts across all of the NOAA regions as of May 18. Since then, NOAA has actually added 8 charts, making 946 charts total. The 948 charts in total contain about 1 gigabyte of data. During the 42 days we tracked NOAA, there were 334 chart updates, or more than 1/3. The most updates in a day were made on May 24/25, with 56 updates.
Below is the number of charts that have been updated on each day:
The diagram is a little bumpy since they update lots of charts on some days and some days none at all. Here is the same data, but with the information smoothed out with a 7 day rolling average:
You can see the average is around 8 or so chart updates a day.
We'll keep digging into this information about providing more information about it, such as the regions that are updated the most, what is in the updates, etc. Also, we have some new features planned for our apps, such as allowing mariners to highlight recent changes to their charts to try to avoid any surprises.