It's a 2nd order lever. Water is pivot, boat is load, arm is effort.
An oar is a lever
A lever is a machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum.
a second class lever
blade/oar
The rowing blade is at the end the oar, and is the part of the oar that goes into the water to propel the boat forward after you take a stroke. The blade is usually shaped like a square.
Rowing has a lot to do with physics. The only way that a boat is moved is, how? By applying force (leg drive) to the blade in the water. It also has to do with simple machines and trajectory. The rigger is used as a pivot point for the oar.
wheel and axle
It is called feathering your oar
Drive.
using an oar to propel ones self in the water using a boat
That is called rowing. A boat can also be propelled with one oar off the stern and that is called sculling.
In order to back a rowing boat, the rowers twist the oar handle 180 degrees turning the blade (end of the oar) around backwards. Then the rowing stroke is done in reverse. The blade is placed in the water toward the stern, then the rower pushes (rather than pulls) the oar handle away from their chest sending the blade through the water toward the bow of the boat. As long as each rower that is "backing" is paired with another rower that holds an oar on the opposite side of the boat who is also backing, this motion will "back" the boat down, rather than send it forward.
The smallest rowing sweep boat (one oar per person) is a pair with 2 people, one person rowing each side. The smallest rowing sculling boat (2 oars per person) is a single, one person rowing both sides. Source: I am a rower B)