BTW, given Jack's DOB, he either lied about his age & joined the Navy or one of his parents had to sign for him.(My dad was born 7/1927 & he quit in senior year of high school to get into war before it was over; his "mommy" had to sign the paperwork, lol, because he was only 17.)If Jack told a little white lie to enlist that could be the reason you can't find info; Naval records would have a different DOB for him.Also, you stated he was only in the service for a short time.The age factor figures into that also. He could have enlisted right before war was over.
If you haven't already done so, try getting the newspaper obit; most veterans had something in obit about military service.Also might want to check local VFW & see if he was a member.