Any sloop firing at any target subtracts 2. If you draw a chit with a 1 or a 2 on it, it is treated as a 0. A chit with a 3 is treated as a chit with a 1, etc. Any extra damage; such as crew, rudder, mast, etc, is treated normally. It may be necessary to have chits to place on the damage chart to keep track of the reduced firepower of sloops.

I also suggest this for the frigates armed with 12 pounders, only with a -1 instead.