Please click on Earhart Project, then click on "Tighars extensive archive of historical documents....", finding "The Earhart Project Archiives finding any subject", then scroll to "Post-loss Signals with Tide information" click on "Statistics with Tides" this brings you to the chart called "Post-loss Signal Statistics for Sources at Gardner". Ric found it with no trouble.
I agree that GMT is universal and easy. Don't change the chart. sunrise was at 1747 GMTon July 2, 1937 (probably will be this year too), sunset was at 0538GMT, midnight was at 1130GMT.
I was going nuts trying to correlate the daytime, nightime, hightides, lowtides etc with the messages that is why i found this difference.