Here are the rowers in action.
Two different types of boat are used and reflect the two forms of rowing: sweep rowing and sculling. In sweep rowing each rower handles a single oar in sculling a rower uses two oars, or sculls.
The sweep boats (each rower has one oar) can have a coxswain (a person who steers the shell using a rudder). So we can have a Coxed Pair (2+), a Coxless Pair (2-), a Coxed Four (4+), a Coxless Four (4-), a Eight (8+).
The Sculling Boats (each rower has two oars) only in rare cases have a coxswain. Steering is generally accomplished by applying more power or pressure to the oar(s) on one side of the shell. So we can have a Single (1X), a Double, a Double (2X), a Quadruple (4X), an Octuple (8X).