The Navy had 8 PE's, which stands for patrol craft, and apparently they only had numbers, no name, and they were called "Eagle Boats." One PE was lost to a German submarine
in WWII. All 8 PE's had been commissioned in 1919, and all were built by Ford Motor Company. They were all alike and had a displacement of 430 tons, length was 200'9" a beam of
25'9", and they had a draft of 13'6". The top speed of an Eagle Boat was 18 knots. They were crewed by 68 men, and the ship was armed with a single 4" 50 caliber gun. A sailor would
have called the gun a "four inch fifty." That simply means the bore was 4 inches, and the length of the barrel was 50 times 4, or 200 inches long.
This is a picture of PE 56, and she was sunk by a U Boat in April of 1945. Looking at the photo it looks like this one was armed with two guns, one gun fore and one aft.
I don't know where you got Chapman's rank as Lieut. Commander, in 1922 he was a Lieutenant, which is the same rank as a Captain in the army. The crest on the box is the
crest for the Naval Academy class of 1922. I couldn't find out anything on Chapman, but the boat was sold by the Navy in 1946. If Chapman was a Lieut. in 1922, he would
have had more than 20 years of service before WWII. If you have information that he was a Lieut. Commander serving aboard PE 48 in 1941, then he was very near retirement,
and may have been held over for the duration. As a Lieut. Commander he also would have been the Captain of a ship that size. That's about all I can come up with.