Ships were classified or rated according to the number of cannon they carry. Cannonades were never included in the number, although rated ships could carry up to twelve 24 or 32-pounders.
All rated ships (1st to 6th) were commanded by a POST CAPTAIN. Sloops, bombs, fire ships and ships armed en flute, that is a rated warship with some or all of its guns removed and used as a transport ship, were commanded by COMMANDERS. Smaller vessels like schooners and cutters were commanded by LIEUTENANTS. Sometimes a MASTER or a MIDSHIPMAN would command a very small vessel or a sloop used to carry stores. A LIEUTENANT, a MIDSHIPMAN or a MASTER'S MATE could be put in temporary command of a captured prize.
SHIPS-OF-THE-LINE were those which were powerful enough to take their place in the line of battle. That is, a 3rd Rate or larger which carried guns on two or more decks. The rated ships smaller than this were known as FRIGATES and carried all their guns on a single upper deck.
1st Rate 100 guns or more 875 to 850 men *
2nd Rate 98 to 90 guns 750 to 700 men
3rd Rate 80 to 64 650 to 500
4th Rate 60 to 50 420 to 320
5th Rate 40 to 32 300 to 200
6th Rate 28 to 20 200 to 140
Sloops 18 to 16 125 to 90
Gun-Brigs & Cutters l4 to 6 5 to 25
* This number was increased by 25 when used as an Admiral's flagship, by 20 with a Vice Admiral and 15 with a Rear-Admiral.