How to keep a 1976 20' MA from sinking at the dock

[Callipygian]

I was planning on adding a second bilge pump. I am talking about the floor drains in the corners that drain out the bottom of the boat when its moving. None of them drain into the bilge. I have one drain hole in the center, just in front of splashwell, at floor level, that has been sealed up. Not sure if that originally drained into the bilge. EggSuckingDog - what do you mean by drains over the side and 415? Geoffrey