Modern Navigation: Some things that have changed

NOAA is sunsetting traditional NOAA Paper Charts. This means the end of paper and raster nautical chart Production, and the introduction of NOAA custom charts. 

Per USCG: (In alignment  with the change above), "the Coast Guard will transition from using NOAA Paper  Chart Numbers and Editions/Dates for disseminating Marine Safety  Information (MSI) to using Official Waterway Names. 

• How You Will Access LNMs and Light Lists:  The LNM and Light List data will now be available in a geospatial  format, which will allow you to visualize information interactively on a  map/chart. You can use your mouse wheel or the +/- buttons in the upper  left portion of the screen to zoom in or out and navigate to your  desired area on the map/chart. Once the area is displayed, you can  generate a PDF of the LNM or Light List for that specific area, which  you can then save and/or print. Alternatively, you can use a fillable  form on our website to select your waterway by name from the Light List  and generate the LNM or Light List.  
• LNM and Light List Data Refresh Rate: LNM  data will be refreshed every fifteen minutes.  Light List data will be  refreshed every 24 hours.  This will give you a much more up-to-date  operating picture, designed to enhance your efficiency and improve  safety in your area of transit or planned routes.  
• Elimination of Weekly Files: Weekly  LNMs, Weekly Light List Correction Files, Daily Discrepancy Files, and  the Summary of Light List Changes will no longer be published to focus  on providing the most up-to-date and accessible format. In the near  future, we will also publish an Application Programming Interface (API)  for interested parties to access the data externally. 

https://www.thevintagenews.com/2017/02/23/depth-sounding-techniques-that-preceded-the-modern-day-sonar-technology/

https://themaritimepost.com/2021/01/07/video-why-ships-speed-is-measured-in-knots/?fbclid=IwAR2ALzZrY9KmlSU6CxNI3f6IzFfbP6pt3eXbe29ceqdnYquLT8pV8KTJvz8