Now I'm a little confused. I looked at replacement pieces for the cockpit drains, and those use a "3/4" sized thru hull. There's a "5/8" size also but that looks pretty small. I can see the sink drain being the same size as the cockpit drains, but the bilge thru hull has to be bigger. Heh...I just realized I could probably check the hose at the bilge pump right?