In the Boston area during WW2 what would the common use of an all green or all red buoy be? Aside from submarine detection.
The Uniform Lateral System of navigation was established in 1936 and in that system green buoys mark the port (left) side of a channel and red buoys mark the starboard (right) side of a channel.
You can look under section 517 [here] (https://books.google.com/books?id=pXjHDnIE_ygC&pg=PA73&lpg=PA73&dq=1936+buoy+navigation&source=bl&ots=Ujtni6huRU&sig=Q28JvmBiahkC_4g9U9clAqRO9cw&hl=en&sa=X&ved=0ahUKEwjg8ZGS7KLLAhWDGx4KHX91BZ8Q6AEIMDAD#v=onepage&q=1936%20buoy%20navigation&f=false) for the history part
You can look at page 6 [here] (http://www.uscgboating.org/images/486.PDF) for pictures representing the use of buoys