Father's surname

Hi, just wanna ask if meron dito same situation kagaya namin. Father po ksi ng baby ko is Seaman and hindi pa kami married. Due date ko is May 2021 and possible nasa barko na ulit siya that time. Paano po kaya maiaapelyido sakanya baby namin if wala sya kapag nanganak ako para pumirma sa birth certificate? Possible po ba yung thru scan then eemail ipapadala sakanya tapos ipapadala ulit sakin? Or is there any other options? Thank you.