A rower who uses two oars at the same time, one in each hand; this allows smaller boats to be rowed sculling, than sweep rowing. A pair being the smallest sweep boat with two people each with one oar. A single being the smallest sculling boat, with one person but two oars
To avoid confusion sweep and scull boats are named differently, a four man sweep boat is called simply "four", while a four man sculling boat is called " Quadruple scull" or just "quad"
The abbreviation for sculling boats is the number of rowers in the boat followed by an "x" to denote a scull then a "+" or "-" to denote coxed boats to coxless boats
Coxed Quadruple scull is "4x+"
Coxless Quadruple scull is "4x-"