Temporary custody when i leave for marines?

im going into the marines soon. im the single father of a little boy and i need a form to sign over temporary custody to my mother while im gone. the recruiter didnt know what i needed. i talked to a friend of mine who is a paralegal and she said she thinks i need a temporary guardianship order but isnt sure. i could prolly find out by going to the court house but i was trying to avoid that whole mess. if you know what i need or know of a website with answers that would be helpful