self bailing scuppers

[flounder]

I have a 1975 cc redoing transome there are two drains in floor that go through the bottom of boat aft deck corners, I have not had this boat in the water ever are these floor drains/scupper drains I would think if left un plugged seawater would come in trying to understand what they are for was thinking of packing them out. any help please thank you stephen k