An oar is an implement used for water-borne

propulsion Propulsion is the generation of force by any combination of pushing or pulling to modify the translational motion of an object, which is typically a rigid body (or an articulated rigid body) but may also concern a fluid. The term is derived from ...

. Oars have a flat blade at one end. Rowers grasp the oar at the other end. The difference between oars and

paddle A paddle is a handheld tool with an elongated handle and a flat, widened end (the ''blade'') used as a lever to apply force onto the bladed end. It most commonly describes a completely handheld tool used to propel a human-powered watercraft by p ...

s is that oars are used exclusively for

rowing Rowing is the act of propelling a human-powered watercraft using the sweeping motions of oars to displace water and generate reactional propulsion. Rowing is functionally similar to paddling, but rowing requires oars to be mechanically a ...

. In rowing the oar is connected to the vessel by means of a pivot point for the oar, either an oarlock, or a thole. The oar is placed in the pivot point with a short portion inside the vessel, and a much larger portion outside. The rower pulls on the short end of the oar, while the long end is in the water. By contrast, paddles are held in both hands by the paddler, and are not attached to the vessel. Rowers generally face the

stern The stern is the back or aft-most part of a ship or boat, technically defined as the area built up over the sternpost, extending upwards from the counter rail to the taffrail. The stern lies opposite the bow, the foremost part of a ship. O ...

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 pivots in the oarlock, and the end in the water moves towards the stern, providing forward

thrust Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction to be applied to that ...

. For thousands of years vessels were powered either by

sail A sail is a tensile structure, which is made from fabric or other membrane materials, that uses wind power to propel sailing craft, including sailing ships, sailboats, windsurfers, ice boats, and even sail-powered land vehicles. Sails may b ...

s, or by the mechanical work of rowers, or by paddlers. It is common for an oar propelled vessel to also have the option to be powered by sail, both in antiquity (for instance the

galley A galley is a type of ship optimised for propulsion by oars. Galleys were historically used for naval warfare, warfare, Maritime transport, trade, and piracy mostly in the seas surrounding Europe. It developed in the Mediterranean world during ...

) and more recently.

History

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 The Hemudu culture (5500 BC to 3300 BC) was a Neolithic culture that flourished on the Coastline of China, Chinese coast, just south of the Hangzhou Bay in Jiangnan in modern Yuyao, Zhejiang, China. The culture may be divided into early and la ...

site at

Yuyao Yuyao () is a county-level city in the northeast of Zhejiang province, China. It is under the jurisdiction of the sub-provincial city of Ningbo. It is located west of central Ningbo, east of Hangzhou, bordering Hangzhou Bay in the north. Yuyao ...

Zhejiang ) , translit_lang1_type2 = , translit_lang1_info2 = ( Hangzhounese) ( Ningbonese) (Wenzhounese) , image_skyline = 玉甑峰全貌 - panoramio.jpg , image_caption = View of the Yandang Mountains , image_map = Zhejiang i ...

, in modern China. In 1999, an oar measuring 63.4 cm (2 ft) in length, dating from 4000 BC, was unearthed in

Ishikawa Prefecture is a Prefectures of Japan, prefecture of Japan located in the Chūbu region of Honshu island. Ishikawa Prefecture has a population of 1,096,721 (1 January 2025) and has a geographic area of 4,186 Square kilometre, km2 (1,616 sq mi). Ishikawa Pr ...

, Japan.

Construction

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" (or button), often made of leather, 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.

Physics

Oars are

lever A lever is a simple machine consisting of a beam (structure), beam or rigid rod pivoted at a fixed hinge, or '':wikt:fulcrum, fulcrum''. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, l ...

s. Which class of lever depends on the

frame of reference In physics and astronomy, a frame of reference (or reference frame) is an abstract coordinate system, whose origin (mathematics), origin, orientation (geometry), orientation, and scale (geometry), scale have been specified in physical space. It ...

. From the rower's perspective, the oar can be seen as a Class I lever. The oar is fixed in the oarlock, the rower pulls on the handle, and the blade moves in the opposite direction to propel the boat. The blade is further from the oarlock than the rower's hands. So, the heavy force of a short rowing motion becomes a smaller force over a greater distance. From an observer on the shore, the oar is instead a Class II lever. Here, the fulcrum is the ''blade'', planted in the water. The rower pulls on the handle and the boat moves along with them. The "Class II" perspective is important to competitive rowing. Effective rowers learn to lever the boat past the end of the blade, rather than pulling the blade through the water. The World Rowing Federation rulebook defines oars as Class II. Both the Class I and Class II perspectives can be used to calculate the forces on the rower, boat, and water, with equivalent results. The calculations are simpler for the Class I perspective. The

mechanical advantage Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for ...

of the oar depends on the length of the oar from the oarlock to the blade, compared to the length from the oarlock to the rower's hand(s). The further away from the oarlock the blade is, the more difficult it is to row and the more distance each stroke will move.

Balanced oar

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 or to drill an hole inside the handle for a distance of about and add about 12 oz of lead secured by epoxy resin glue. For a 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. As the rower is expending less energy accelerating the (now-reduced) mass of the oar back-and-forth, and will experience less fatigue constantly exerting downward force on the handle (vs. an unbalanced version) -- this type of oar is more efficient and thus preferable for long-range rowing.

Oars used for transport

The oars used for transport come in a variety of sizes. The oars used in small

dinghies A dinghy is a type of small boat, often carried or Towing, towed by a Watercraft, larger vessel for use as a Ship's tender, tender. Utility dinghies are usually rowboats or have an outboard motor. Some are rigged for sailing but they diffe ...

or rafts can be less than 2 metres long. In classical times

warship A warship or combatant ship is a naval ship that is used for naval warfare. Usually they belong to the navy branch of the armed forces of a nation, though they have also been operated by individuals, cooperatives and corporations. As well as b ...

s were propelled by very long oars that might have several oarsmen per oar. These oars could be more than a

dozen A dozen (commonly abbreviated doz or dz) is a grouping of twelve. The dozen may be one of the earliest primitive integer groupings, perhaps because there are approximately a dozen cycles of the Moon, or months, in a cycle of the Sun, or year ...

metres long. According to Callixenus, as cited by

Athenaeus Athenaeus of Naucratis (, or Nαυκράτιος, ''Athēnaios Naukratitēs'' or ''Naukratios''; ) was an ancient Greek rhetorician and Grammarian (Greco-Roman), grammarian, flourishing about the end of the 2nd and beginning of the 3rd century ...

, in the great ship of Ptolemy the oars of the upper tier were over in length with handles leaded so as to equalize the weight inboard and outboard.

Oars used for competitive rowing

The oars used in

competitive rowing Rowing, often called crew in the United States, is the sport of racing boats using oars. It differs from paddling sports in that rowing oars (called blades in the United Kingdom) are attached to the boat using rowlocks, while paddles are n ...

are long (250–300 cm) poles with one flat end about 50 cm long and 25 cm wide, called the blade. The part of the oar the oarsman holds while rowing is called the

handle A handle is a part of, or an attachment to, an object that allows it to be grasped and object manipulation, manipulated by hand. The design of each type of handle involves substantial ergonomics, ergonomic issues, even where these are dealt wi ...

. While rowing, the oars are supported by metal frames attached to the side of the boat called riggers, while the oar fits into the oarlocks at the ends of each rigger. Classic oars were made of

wood Wood is a structural tissue/material found as xylem in the stems and roots of trees and other woody plants. It is an organic materiala natural composite of cellulosic fibers that are strong in tension and embedded in a matrix of lignin t ...

, but modern oars are made from

synthetic Synthetic may refer to: Science * Synthetic biology * Synthetic chemical or compound, produced by the process of chemical synthesis * Synthetic elements, chemical elements that are not naturally found on Earth and therefore have to be created in ...

material, the most common being

carbon fibre Carbon fiber-reinforced polymers (American English), carbon-fibre-reinforced polymers ( Commonwealth English), carbon-fiber-reinforced plastics, carbon-fiber reinforced-thermoplastic (CFRP, CRP, CFRTP), also known as carbon fiber, carbon comp ...

Oars used as trophies

The sport of competitive rowing has developed a tradition of using an oar as a memento of significant race wins. A 'trophy oar' is not presented at the end of the race as a more familiar precious metal cup might be, but rather given by the club, school or university that the winning crew or rower represented. Trophyoars

A trophy oar is a competition oar that has been painted in the club colours and has then had the details of the race signwritten on the face of the blade. The most common format has the coat of arms or crest of the club or school positioned in the centre, with the crew names and the race details arranged around this. Many older universities (

Oxford Oxford () is a City status in the United Kingdom, cathedral city and non-metropolitan district in Oxfordshire, England, of which it is the county town. The city is home to the University of Oxford, the List of oldest universities in continuou ...

and

Cambridge Cambridge ( ) is a List of cities in the United Kingdom, city and non-metropolitan district in the county of Cambridgeshire, England. It is the county town of Cambridgeshire and is located on the River Cam, north of London. As of the 2021 Unit ...

for example, as well as Yale and Harvard) and their colleges have long histories of using the trophy oar and many examples are on display in club houses around the world.

In culture

Norway Norway, officially the Kingdom of Norway, is a Nordic countries, Nordic country located on the Scandinavian Peninsula in Northern Europe. The remote Arctic island of Jan Mayen and the archipelago of Svalbard also form part of the Kingdom of ...

, both

Fedje Municipality Fedje is an island municipality in the Nordhordland region of Vestland county, Norway. The administrative centre of the municipality is the Fedje (village), village of Fedje. The traditional economic activity of the inhabitants is fishing. The ...

and Herøy Municipality both have oars in their

coat of arms A coat of arms is a heraldry, heraldic communication design, visual design on an escutcheon (heraldry), escutcheon (i.e., shield), surcoat, or tabard (the last two being outer garments), originating in Europe. The coat of arms on an escutcheon f ...

. Oars have been used to describe various animals with characteristics that closely resemble the said rowing implement. The members of the Family Regalecidae, elongated deep-sea fishes, are called oarfish because their body shape is similar to that of an oar. The hawksbill turtle's genus of Eretmochelys is derived from the Greek root ''eretmo'', which roughly translates to ''oar''. The turtle was so-named because of the oar-like shape of its front flippers.

References

External links

Oar positions
1775 – 1783 British Navy {{Authority control Marine propulsion Rowing equipment Water sports equipment