Regal 53 SC Owner's Manual page 416

UNDERWATER HARDWARE- SEACOCKS
Inspect the thru-hull seacocks before each outing. Make
sure the connections between the output hose and the
valve are tight. Look for water leaks around the area where
the valve and hull meet.
Every 30 days open and close each thru-hull valve several
times. This will guard against the valve seizing in the open
or closed position. Also, make sure the valve handle is
tightly fastened. Secure any loose valve handles.
HANDLE
IN-LINE
TYPICAL SEACOCK
70
Chapter 8
OPEN
POSITION
CLOSED
POSITION