There are 2 townlands in Ireland named Ballymacaw, one in Co Cork and the other in Co Waterford. Your family appear to have lived in the Waterford one. Here’s a birth for a Jane Goble on 20.10.1900 at Ballymacaw. I note that William James Goble served in the Coastguard.
https://civilrecords.irishgenealogy.ie/churchrecords/images/birth_returns/births_1900/01972/1760365.pdf
Here’s the household in the 1901 census:
http://www.census.nationalarchives.ie/pages/1901/Waterford/Rathmoylan/Ballymacaw/1766891/
According to the house & building return their house had 3 windows at the front and 3 rooms inside. It was right next door to the Coastguard station. They are numbered 26 & 27 respectively on the census but those were the enumerator’s private numbering system and bear no relation to any street numbers that might exist today. According to this link the coastguard cottages are still there up on the cliff and look lovely (post dated 20.3.2021):
https://www.coastguardsofyesteryear.org/forum/viewthread.php?thread_id=5266
Photo of the cottages here:
https://www.coastguardsofyesteryear.org/photogallery.php?photo_id=33
One of the cottages was up for sale in 2011 for €250,000. They were reportedly built in the 1880s so same buildings as your ancestor served in, though they will have been modernised over the years I am sure.
https://www.irishexaminer.com/property/arid-20156005.html
By 1905 the family was stationed in Ballinacourty, near Dungarvan:
https://civilrecords.irishgenealogy.ie/churchrecords/images/birth_returns/births_1906/01748/1689907.pdf
And in 1907 they were at Rock Island, Co Cork:
https://civilrecords.irishgenealogy.ie/churchrecords/images/birth_retur…
1911 census the family has moved again, to Kilhile in Co. Wexford. Note Married 16 years. 6 children born, all still alive.:
http://www.census.nationalarchives.ie/pages/1911/Wexford/Ballyhack/Kilhile/688919/