Sculling boats include:
                (Note:  the stuff in brackets is the abbreviation used on race schedules)

bullet Single (1X) - shell rowed by one athlete, using two oars.

 

bullet Double (2X) - shell rowed by two athletes, each using two oars.  The rower in bow seat steers the shell.

 

bullet Quad (4X) - shell rowed by four athletes, each using two oars.  The rower in bow seat steers the shell.

            OR

bullet Coxed quad (4X+) - shell rowed by four athletes, each using two oars.  A coxswain steers the shell and calls the stroke.