Monthly Archives: June 2010

First thoughts

All novice rowers are taught not to race the recovery. Many rowers and rowing coaches develop a sense of “good” rowing. It is a question of balance, rhythm, power, ease of motion, yin and yang, feeling for the water, etc. We immediately recognize the skilled rower, and by teaching our pupils we pass on the art of rowing from generation to generation. So, all rowers are taught not to race the recovery, and for a skilled rower, it just ‘feels’ wrong, and it hurts to see a novice rower race the recovery.

We know when the rowing feels good, when the stroke feels light and we let the boat run easily through the water. We don’t waste energy to move the boat. No, we almost effortlessly and oh so playfully persuade our shell to slide through the water. We are using the right rhythm. We are rowing in sync with the rest of the crew. We are one with the elements, with the crew, with the boat.

Not racing the recovery is where it all starts. So I had this all rationalized: Conservation of momentum tells us that if we race the recovery, we force a sudden increase in the shell speed, which is a very bad idea because the shell’s drag resistance scales with the square of the shell velocity. On the other hand, doing a really slow recovery is not smart either, because the drag force would decelerate the boat, and one would need a very strong stroke to compensate. So, by hand-waving arguments I had concluded that there must be an optimum stroke-recovery ratio! All I needed now was the back of a napkin to jot down a few equations and voila!

The back of the napkin turned into a notebook full of notes, which then turned into a numerical model. So is there an optimum stroke recovery ratio? Perhaps. Let’s see.

Is racing the recovery a bad idea? You bet!

Physics of Rowing

Here is where I intend to publish my modeling of the mechanics of rowing.

Most of what I will publish here is based on a few sources on the web.

  1. Physics of Rowing for the basic equations
  2. Bill Atkinson’s page on modeling the rowing stroke
  3. A MatLab model by Marinus van Holst
  4. Rowing Biomechanics Newsletter by Dr. Valery Kleshnev

Nothing new here, so please move on to one of those links now for some interesting reading.

What I have done is:

  • Created a Phyton/NumPy model based on the equations  by Marinus van Holst
  • Slightly improved Marinus’ model
  • Generate a lot of numerical results
  • Use the model to calculate rower power for rowing world records in various boats and weight categories, and compare these number with available data

Why do I publish this if it’s nothing new? Basically I hope to get some reactions, especially hoping to improve the model, perhaps discover a few discrepancies. Find some people who are also interested in the physics of rowing.

I intend to use this blog to describe my model and the results. I have a family, a job and also spend a lot of time doing the actual rowing, so be patient. It will take time.