Sculling

[2][3] Sculling is a form of rowing in which a boat is propelled by one or more rowers, each of whom operates two oars, one held in the fingers and upper palm of each hand.

These shells are classified according to the number of rowers that they can hold: singles have one seat, doubles have two, and quads have four.

In keeping with this pattern, quads rowed by three people (due, for instance, to a temporary shortage of rowers) are often colloquially referred to as "triples".

To prevent this from impacting the balance of the boat, one oarlock (conventionally the starboard one, to the rower's lefthand side) is rigged higher than the other prior to rowing.

[4] This prevents the oar handles and the sculler's thumbs from colliding with one another and causing a crab or other problems.