Oars

An oar is an implement used for water-borne propulsion. Oars have a flat blade at one end. Rowers grasp the oar at the other end. The difference between oars and paddles are that paddles are held by the paddler, and are not connected with the vessel. Oars generally are connected to the vessel by means of rowlocks or tholes which transmit the applied force to the boat. In this system (known as a second class lever) the water is the fulcrum.

Rowers generally face the stern of the vessel, reach towards the stern, and insert the blade of their oar in the water. As they lean back, towards the vessel's bow, the blade of their oars sweeps the water towards the stern, providing forward thrust – see lever.

For thousands of years vessels were powered either by sails, or the mechanical work of rowers, or paddlers. Some ancient vessels were propelled by either oars or sail, depending on the speed and direction of the wind (see galley).

Rowing oars have been used since the early Neolithic period. Wooden oars, with canoe-shaped pottery, dating from 5000–4500 BC have been discovered in a Hemudu culture site at Yuyao, Zhejiang, in modern China. In 1999, an oar measuring 63.4 cm (2 ft) in length, dating from 4000 BC, was unearthed at Ishikawa Prefecture, Japan.

Oars have traditionally been made of wood. The form is a long shaft (or loom) with a flat blade on the end. Where the oar connects to the boat there is a "collar" which stops the oar slipping past the rowlock. Oars usually have a handle about 150mm long, which may be a material sleeve or alternatively an ovoid shape carved to fit the hands.

This is a normal, usually wooden oar to which weight has been added at the inboard end so that the blade end is noticeably lighter and easier for a rower to operate without fatigue. The two methods of adding weight are to either have a much larger section in the oar immediately next to the handle for a distance of about 450 millimetres (18 in) or to drill an 18-millimetre (0.71 in) hole inside the handle for a distance of about 150 millimetres (5.9 in) and add about 12 oz of lead secured by epoxy resin glue. For a 7-foot (2.1 m) oar the balance point is about 12 inches outboard of the rowlock. Often surplus wood is removed from the blade's width and thickness and at the neck between the blade and the shaft to further reduce outboard weight. This type of oar is much better for long-range rowing.

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Wikipedia