They stated that Sophie C was the fifth mail boat. Robert and Arthur, Dolphin, Uncle Sam and Uncle Sam II.
They forgot the
Marshall Foch, which was used in 1932 & 1933 (dismantled in 1941) and The Tonimar was brought to the lake in 1940, delivering mail from 1941 - 1965. I believe that Uncle Sam II Came to the lake in 1962.