1st and or 2nd rates (90 + gun ships, 3 deckers)
3rd rates (64 to 80 gun ships, 2 deckers)
4-6th rates (roughly 30 to 60 ships, 4th rates were 2 deckers, 5th and 6th rates had 1 deck)
'Unrated' (includes most naval/privateer vessels with <= 24 guns)