Physics of Rowing

Prepared by Anu Dudhia (anu.dudhia@physics.ox.ac.uk) from Oxford University Atmospheric, Oceanic and Planetary Physics Recent modifications:
This site contains a series of pages covering the basic Physics of Rowing and, below, some frequently asked questions related together with links to where answers can be found.

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None of the following information is copyright, so feel free to reproduce any or all of it, credited or uncredited as you see fit (although I might be a bit miffed if anyone else tried to pass it off as their own work).


FAQ: Basic Physics of Rowing

  1. Propulsion
    • Why does the blade have to slip in the water? (when it doesn't if you push off a solid object?)
  2. Resistance
    • What causes a boat to slow down?
    • Why don't you go twice as fast if you pull twice as hard?
  3. Kinetic Energy
    • Why are 'cleavers' a good idea ? (when you can get the same impulse from smaller blades?)
  4. Centre of Mass
    • Why do boats continue to accelerate (and move quickest) after the end of the stroke?
  5. Speed Variation
    • Why is it more efficient to row a piece with constant split-times?
    • Why is it more efficient to keep the hull speed as uniform as possible during the stroke?
    • Why were 'sliding rigger' boats banned?
  6. Balance
    • Why do/don't boats balance?
    • Why is it easier to balance a moving boat?
  7. Levers
    • What type of lever is an oar?
    • Why does the boat move forwards although I'm pushing it backwards with my feet?
  8. Gearing
    • What is meant by the gearing of an oar?
    • Why is gearing expressed in terms of the span (or spread) rather than the inboard?
    • Why is changing the span 1cm supposed to be 3 times as effective as moving the button the same distance?
    • What are CLAMS and why are they used?
    • Why are cleavers shorter than the equivalent Macon oars?
  9. Newton's Laws of Motion

FAQ: Physics of Weight & Rowing

  1. Introduction
    • How do erg scores/boat speed depend on bodyweight?
  2. Relationship between Power and Weight
    • Why and how do Aerobic and Anaerobic power depend on weight?
  3. Power/Weight Ratios
    • How do Power/Weight ratios depend on weight?
  4. Relationship between Weight and Erg Speed
    • Why do heavier rowers have an advantage on Erg scores
    • Where does the 2/9 (or 0.222) exponent in erg-conversion scores come from?
  5. Relationship between Weight and Boat Speed
    • Why are heavier rowers faster than lighter rowers?
    • Why is this difference less obvious over long distances?
  6. Speeds of different Boat Classes
    • Why are boats with more rowers faster?
    • How much faster are they?
    • How fast should an octuple scull be?
  7. Effect of deadweight
    • What is the effect of deadweight on boat speed?
    • How much does the weight of the cox affect the boat speed?
  8. Relationship between Erg Score and Boat Speed
    • How do you convert erg-scores of rowers of different weights into equivalent boat speed?
    • If I lose weight, how much faster would I scull?
    • If I lose weight, how much should my erg score be allowed to drop in order to maintain the same boat speed?
  9. Effect of Boat Weight on Boat Speed
    • Is a "lighter" boat necessarily a "faster" boat?

FAQ: Physics of Stream/Depth & Rowing

  1. Introduction
    • Which feels 'heavier': rowing upstream or downstream?
  2. Viscosity
    • What is viscosity?
    • Why is viscous drag said to be proportional to velocity?
  3. Boat Resistance
    • Why does boat resistance vary as velocity-squared? (when viscous drag is usually said to be proportional to velocity)
  4. River Flow
    • Why does a river flow quickest where it is deepest?
  5. Upstream/Downstream Resistance
    • Why does rowing upstream feel 'lighter' than rowing downstream?
  6. Shallow Water Resistance
    • Why does rowing in shallow water feel heavier than deep water?
    • How shallow does water have to be before you notice?
  7. Upstream/Downstream times
    • Why is the average time for upstream + downstream pieces slower when the stream is faster? (when you'd expect the stream effect to cancel)

FAQ: Physics of Ergometers

  1. Introduction
    • What are the different types of Ergometers?
    • Where can I find more information about each type of Ergometer?
  2. Mechanics of Rotating Bodies
    • How do Newton's Laws apply to rotating bodies ?
  3. Power Dissipation
    • Why/how do ergometers lose speed ?
  4. Power Supplied
    • How does power supplied turn into rotation speed?
    • How does power relate to the flywheel speed ?
  5. Changing the Cog
    • What is the effect of changing the cog (sprocket) size?
  6. Changing the Damping
    • What is the effect of changing the damper setting ?
  7. Measuring the Damping
    • How does the ergometer 'know' what damper setting is used ?
    • What other effects are/are not allowed for by the ergometer ?
  8. Measuring the Power Supplied
    • How does the ergometer calculate the indicated 'Power' ?
  9. Indicated Speed (Splits) and Distance
    • How does the ergometer calculated the speed and distance ?
  10. Indicated Power v. Indicated Speed (Splits)
    • What is the relationship between indicated Power and Speed?
  11. Power v. Indicated Calories
    • What is the "Calories" output on the monitor ?
    • What is the relationship between indicated Power and Calories?
  12. Dynamic v. Static Ergs
    • What is the difference between moving and stationary ergs?
    • Why are 'dynamic' ergs better boat simulators
    • Why do you get higher scores using the Concept 'slide'
  13. Effect of Rating
    • How does rating affect the power required ?
    • Why do people erg at lower rates than they row/scull?
  14. Effect of Altitude
    • What is the effect of altitude on erg scores?
  15. Glossary of terms used in Rotational Mechanics
    • What are the various terms used in studying rotational systems?

Bibliography and References

  1. Atkinsopht
  2. Concept II
  3. Federation Internationale des Societes d'Aviron (FISA)
  4. Balance of Racing Rowing Boats (Steve Kerr, document now hosted locally)
  5. Hydrodynamics Articles (Leo Lazauskas)
  6. Weight/Sex/Age Adjusted Ergo Ladder (Jeremy Martin)
  7. Rowing Physiology and Performance (Stephen Seiler)
  8. Physics of Sport (Tom Steiger, originally from Ken Young)
  9. Simulation of Rowing (Marinus van Holst)
  10. Rowing FAQ (Hannes Hofer)
  11. RowPerfect
  12. rowing-x.pert Rowing Bibliography (Florian Caspari)
  13. Physics of Rowing [PDF file] by Chris Pulman, University of Cambridge.
  14. Rowing Rigger Design (Virginia Tech)
  15. Article on Sliding Riggers (from Hear the Boat Sing)

Acknowledgements

The following people have also contributed to the content of these web-pages:
Paul Blomerus, Carl Douglas, Scott Gordon, Dena Hirchak, Marinus van Holst, Dick Nixon, Hans Lohse, Jon Williams.
Anu Dudhia (dudhia@atm.ox.ac.uk)