A rowing oar is made up of several parts. You have the handle, which could be wood (I prefer the grip of this), plastic or rubber. This is for either one or two hands depending on whether it's a sweep blade or a scull blade.
The shaft is usually hollow carbon fibre or some other light materiel, approximately four inches in diameter at the collar (the fitting which allows it to stay still in the gate).
The blade, or the spoon, is of many different shapes. The three basic shapes are the modern hatchet (asymmetric, like a chef's cleaver), old macon (pronounced soft c, classic oar shape) and older pencil (long and thin). They may or may not have a spine running along the spoon in line with the shaft, and they may or may not have hydrodynamic modifications on the end of the spoon to obtain better grip.
The hatchet shape stems from a desire for increased connection and lower slippage. Since the spoon is not moving straight but in an arc, the outer end moves at a different speed to the inner causing slip. The shorter and deeper a blade is the less this occurs.
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.
blade/oar
Scapula
It means to turn your oar so the blade is parallel to the surface of the water
an oar pin is called thole
The middle part of an oar is called a LOOM
4
Oar would probably be the closest, although it isn't really a good likeness.
An oar. Similar to a paddle, an oar is a device with a flat blade used in water propulsion. One distinction between a paddle and an oar is that oars are usually connected to the vessel while paddles are not.
Oar
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.
That's an oarlock.