Not all boats had them, or did they have them at all times. It was not something that could be assigned to anyone. It just happened, a first or second class somehow took the job of being a kind of mother to unruly bubbleheads. They were just men that cared for the crew and took on a somewhat thankless job. Their rate didn't matter TM, EN QM or EM, they just took the job and kept it until they left the boat. When they left, they may or may not have been replaced for some length of time.
They often were found when a COB wasn't up to snuff so to speak, acting as an added buffer between him and the crew. Most I noticed went on to become good COBs themselves, so maybe it was a self-imposed training mission for them.
They helped ride herd on non-quals, reminding and helping them to do what they should. They would make sure you were doing okay, getting along and doing your job. They often watched over the new guys to make sure they didn't run afoul of the rules on board or ashore. They gave timely warnings to avoid certain things and to do others.
"Hemming, why don't you come to Bells tonight with the rest of us?"
"Hemming why don't you catch up on your quals today?"
"Hey! No reading skin books until you're qualified."
"Maybe you better watch what you kid about until you have signed-off in Maneuvering."
"You got enough money to get home this weekend? I'll loan you some."
Often they were in charge of a berthing compartment, Torpedo Room, After Battery, or in the case of the Requin, the Stern Room.
The Stern Room on Requin was where I met my first one. I was told upon reporting aboard to go aft and check in with 'Mother'. Huh? I think, 'Mother', who in the hell would be called 'Mother' on a sub? Oh yeah, this is one of those jokes they play on the new boot, I bet. Well I'm cool, I ain't gonna go marching into the room and ask for Mother and get laughed at.
To the first guy I see, "Ah, I was told to report to the guy in charge to get my rack and stuff."
"Hey Mother, new guy here to baby along."
Next thing I know, I'm shaking hands with a first class Electrician and being assigned a rack, locker, and being in general, given the rules of the place.
"They really call you Mother?"
"Yeah, but you don't have to."
Somehow I realized it was better if I didn't call him that until I had learned to pull my weight and do my job. So I just called him by his last name. By the time I had reached the point I could call him that, I was transferred. But at the last Requin reunion, I looked up as he came in the door.
"Mother! You old wrecked-up bastard, how are ya?"
Then I did something I should have done in August of 1963.
"Thanks Jerry 'Mother' Ender, for all you did for me."