Rowing is a sport in which athletes race against each other in boats, on rivers, on lakes or on the ocean, depending upon the type of race and the discipline. The boats are propelled by the reaction forces on the oar blades as they are pushed against the water. The sport can be both recreational, focusing on learning the techniques required, and competitive where physical size and overall fitness plays a large role. It is also one of the oldest Olympic sports. In the United States, high school and College rowing is sometimes referred to as crew.
A rowlock (UK pron.: //) or oarlock (US) is a brace that attaches an oar to a boat. When a boat is rowed, the rowlock acts as a fulcrum, and, in doing so, the propulsive force that the rower exerts on the water with the oar is transferred to the boat by the thrust force exerted on the rowlock.
On ordinary rowing craft, the rowlocks are attached to the gunwales. In the sport of rowing, the rowlocks are attached to outriggers (often just called "riggers"), which project from the boat and provide greater leverage. In sport rowing, the rowlocks are normally U-shaped and attached to a vertical pin which allows the rowlock to pivot around the pin during the rowing stroke. They additionally have a locking mechanism across the top of the "U" to prevent the oar from unintentionally popping out of the rowlock.