Improving the efficiency of racing shell oars

Brearley, M. N.; Mestre, N. J. De

doi:10.2307/3620769

Cited by 6 publications

(4 citation statements)

References 1 publication

(2 reference statements)

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“…Oarlock displacement is a simple way of achieving the benefits produced by the concept of blade lead angle suggested in an earlier paper by Brearley and de Mestre [2], but without the disadvantages attending that method.…”

Section: Discussionmentioning

confidence: 99%

A Method of Improving Oar Efficiency

Brearley¹

2009

ANZIAM J.

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In boats used for competitive rowing it is traditional for the rowers to use strokes in which the angle between the oar shaft and the perpendicular to the hull centre line is much greater at the catch than it is at the end of the power stroke. As a result, the oar blade is even more inefficient in its action at the catch than it is at the end of the power stroke. This paper shows how boat performance in a race would be improved by reducing the difference in these starting and finishing angles. The claim of improved race performance is supported by a detailed investigation of the dynamics involved in the case of a particular coxless pair whose performance has been recorded by the Australian Institute of Sport. We also suggest an easy way to make the necessary change in boat design.2000 Mathematics subject classification: primary 92C10; secondary 74L15.

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Section: Discussionmentioning

confidence: 99%

A Method of Improving Oar Efficiency

Brearley¹

2009

ANZIAM J.

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“…Of note is a study by Brearley and de Mestre (2000), who found considerable increases in efficiency when the blade is tilted forward with respect to the shaft. This would offset any negative effects caused by oar bending in the mid-part of the stroke (Brearly & de Mestre, 2000). A possible problem with simulation studies like these is that it is assumed that the force input (delivered by the rower) is the same for each situation and as such independent of oar design.…”

Section: Oar Deformation Neglectedmentioning

confidence: 96%

Estimation of the energy loss at the blades in rowing: Common assumptions revisited

Hofmijster

Koning

Soest

2010

Journal of Sports Sciences

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In rowing, power is inevitably lost as kinetic energy is imparted to the water during push-off with the blades. Power loss is estimated from reconstructed blade kinetics and kinematics. Traditionally, it is assumed that the oar is completely rigid and that force acts strictly perpendicular to the blade. The aim of the present study was to evaluate how reconstructed blade kinematics, kinetics, and average power loss are affected by these assumptions. A calibration experiment with instrumented oars and oarlocks was performed to establish relations between measured signals and oar deformation and blade force. Next, an on-water experiment was performed with a single female world-class rower rowing at constant racing pace in an instrumented scull. Blade kinematics, kinetics, and power loss under different assumptions (rigid versus deformable oars; absence or presence of a blade force component parallel to the oar) were reconstructed. Estimated power losses at the blades are 18% higher when parallel blade force is incorporated. Incorporating oar deformation affects reconstructed blade kinematics and instantaneous power loss, but has no effect on estimation of power losses at the blades. Assumptions on oar deformation and blade force direction have implications for the reconstructed blade kinetics and kinematics. Neglecting parallel blade forces leads to a substantial underestimation of power losses at the blades.

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“…Although this assumption is unrealistic, as is plainly obvious to anyone observing the deflection of an oar being rowed, it is made because little is known about either the nature of the bending, in particular the interrelation between the oar bending force and the effect of the bending on the blade forces, or the importance of including it when modelling the stroke [6]. While estimates of oar bending have been calculated using the measured oar force at the oarlock [7], a detailed quantitative analysis of bending behaviour has not yet been performed. Here, the effects of oar bending are calculated by resolving the complex time-varying hydrodynamic load on the oar blade during the drive by using a computational fluid dynamics (CFD) model.…”

Section: Introductionmentioning

confidence: 99%

Modelling the effect of oar shaft bending during the rowing stroke

Sliasas

Tullis

2011

Proceedings of the Institution of Mechanical Engineers, Part P:

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The behaviour of oar shaft bending during the drive phase is examined using a hydrodynamic-based model of the rowing stroke. By modelling the complex time-varying hydrodynamic load on the blade, the amount of shaft bending during the drive can be calculated. It is shown during the first 45 per cent of the drive that the blade rotation rate is up to 30 per cent slower than the oarlock rotation rate as the oar deflects and energy is stored in the flexible shaft. Through the remainder of the drive the shaft unbends, causing the blade to rotate up to 16 per cent quicker than the oarlock as the stored energy is transferred to the water and to shell propulsion. The effects that this bending has on oar blade and handle forces highlight the importance of accounting for oar shaft flexibility when modelling the rowing stroke.

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Improving the efficiency of racing shell oars

Cited by 6 publications

References 1 publication

A Method of Improving Oar Efficiency

A Method of Improving Oar Efficiency

Estimation of the energy loss at the blades in rowing: Common assumptions revisited

Modelling the effect of oar shaft bending during the rowing stroke

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