Dear Jackie Boyd,
Thank you for posting your request on History Hub!
You may be able to learn more about the sailor by examining small details within the photograph. For example, if you are able to identify specific aspects of the uniform and insignia he is wearing, you may be able to determine his military rank or unit. This could also help pinpoint the time period when the photograph was taken. The Naval History and Heritage Command (NHHC) provides some historical information about uniforms and insignia on their website that you may find useful. The NHHC also offers information about the history of Naval Base San Diego, California that may interest you. We suggest that you contact them directly for further assistance.
In addition, the city of San Diego has an online Military Digital Archives that might provide some context for your photo or that might be useful in identifying local landmarks in it.
If the stamp on your photograph includes the name of the photographer or photography studio, then that may be another avenue you could explore. Plus, the second photograph you mentioned could also offer some clues to follow in trying to identify the sailor in the first picture.
We hope this is helpful. Best of luck with your research!