I have been attempting to identify C. R. Mather. Who would’ve been in the Navy in 1913.  I suspect it’s Clarence Ray Mather, But I have not been able to find any more evidence yet. In 1920 it shows him as an electrician at a Navy Yard. His date of birth is in the right timeframe for him to have joined just prior or in 1913. Most results show him going by Ray instead of Clarence.