Because left and right are ambiguous - are you talking about MY left or the boat’s left? Having unambiguous names let’s us differentiate and avoid confusion.
It might be hard to grok the need for this if you’ve never been in a tight spot while sailing or operating a watercraft with a crew - but having this distinction has probably saved thousands of bad incidents from happening.
It might be hard to grok the need for this if you’ve never been in a tight spot while sailing or operating a watercraft with a crew - but having this distinction has probably saved thousands of bad incidents from happening.