Is that your grandfather James at Quay Street, in the town of Skerries on the 1911 census with his parents John and Mary ?
Not sure what sort of documentation you have already...starting with the 1911 census, John Mary and their five children are listed as Catholic, and all born County Dublin, James is age 1 ½, and a check for his birth on the IrishGenealogy website shows that he was registered as James Joseph Creenan born on the 8th of August 1909 in Skerries and that his mother's maiden surname was Owens, his father John is shown as a Sailor. Birth registration s for the other children should also be available on IrishGenealogy..
The 1911 return notes that the couple are married about 13 years, so married c1898, and have had 6 children, five of which are still living as of the 1911 census. The family appear on the same street in Skerries, Quay Street on the 1901 census. Based on the details established from the census returns a further search for a marriage of John and Mary shows that they married on the 4th November 1896, at St. Patrick's RC Skerries, John gave his occupation as sailor and residence as Skerries, Mary gave her residence as Quay Street, Skerries - same street as the 1901 & 1911 census returns. John's father is recorded as Nicholas noted as deceased, and Mary's father is John Owens a sailor, The witnesses to the marriage are Joseph McGowan and Anne Owens.