Spanish minelayers

[patrickren]

At a recent family re-union my mother learned that her late father(a merchant seaman) served on a Spanish minelayer during the Spanish Civil War. Not that remarkable, I admit. But what my mother knew nothing about was that her father took her brother along with him. He was thirteen years old!!!!!!!!
Knowing my grandfather and uncle I have little doubt this is true.
How, if at all, could I get more information on this?
Your help/advice will be greatly appreciated.