Seems like your
winches are missing the split rings. Assuming it's a non-self tailing
Lewmar winch, such as like this:
You will notice a groove around the upper outer edge of the
winch's top bushing. This receives a stainless split ring and locks the large stainless washer to the
winch drum. They are available through
Lewmar (or other mfgr) as spares.