If memory serves....
2 bells for O-4 and below
4 bells for O-5 and O-6
6 bells for O-7 and O-8
8 bells for O-9 and O-10
If they are the CO of the unit, they also get a stinger, which is a single bell when they either step on to the ship, or step on to the pier. I may be a little off on the Admirals. It might be 6 bells for O-7 through O-9, but I think I have it right. However, most units only do the bells for the CO and above.
R/
PO1 Kevin Couture