More detail at
https://shipmar.com/divisions/harbour-and-terminal/pilot-1350/
The Great Lakes-St. Lawrence Seaway System is a 2,340 mile “marine highway” that extends from the Atlantic Ocean to the Great Lakes. This integrated navigation system serves mariners, farmers, factory workers, and commercial interests from the western prairies to the eastern seaboard. Today, the Great Lakes-St. Lawrence Seaway System serves as a Key Supply Chain for the world’s 3rd largest economy. Visit greatlakesseaway.org/our-system/ to learn more!
It has been shown that a majority (51%) of pilot ladders is secured by means of D-shackles, when secured at intermediate length. Previous research (Evans, 2020) has proven that this method has only about 50% of the strength of the pilot ladder when secured at full length (“double ended ladder”), or by means of the “endless-sling” method.