Rowing Efficiency Testing

by Ron Rantilla

Reason for testing
For me, the reason for efficiency testing was to find the answer as to why, using the FrontRower, I was able to outperform conventional sliding seat rowing systems on the same boats.  The difference in sprint speeds was remarkable.  But even in long distance races I was able to beat identical boats by a significant margin.  Was this because I was better trained or stronger than the competition?  Or was it because of the system itself was more efficient? If I was to continue improving the Frontrower, I needed to know the answers.

But efficiency is important to all human powered boaters. With more efficiency, not only can you go faster, but you can go further with the same amount of energy expended.  Going further means seeing more, experiencing more, and having more fun.

But how do you know if the equipment you are using is efficient? Without measurable testing, you can only go by guesswork or advertising hype.

I searched all the publication I could find about efficiency in row boat but found very little useful information on the subject. As an engineer, it is natural for me to set up tests and analyze the results. So that’s what I did.

Using the methods I developed, anyone can do their own efficiency testing.

Defining efficient
Efficient means performing with the least waste of energy. In boats, efficiency varies with speed (the slower you go the more efficient you are). But we don't want to go as slowly as possible for the sake of efficiency. We want to row at some reasonable speed. So for rowing a boat, efficient means: moving a specified boat and load at a specified speed using the least physical effort.

The testing method
The method I used is to row a boat at an exact speed and measure the physical effort required to maintain that speed. Then change some component (such as the oar blades), and measure the effort required to maintain the same speed with the new component. You need to standardize the test conditions. This means: no wind; no current; consistent water depth; and no turning. The easiest way to measure speed is with a GPS. The easiest way to measure effort is with a heart rate monitor.

Using this method, I row my “base” system at a specified speed and record my heart rate over a period of time until it stabilizes. Then I change one component and row the “new” system at the same speed and record my “new” heart rate. The tested component giving the lowest stabilized heart rate number is the most efficient. To get an idea of the magnitude of the efficiency difference, I express the difference as a percentage of the base.
Note that what I am measuring is relative efficiency (not to be confused with absolute efficiency). This means that I can compare components that I have tested with each other only, not to some absolute standard.

Using this system, I can test one component of the propulsion system at a time, or I can test two completely different propulsion systems against each other or even different boats for relative efficiency.

Results
Here are some of the results of my testing that I found to be most interesting:

1. Overall efficiency:
Compared to conventional rowing
At 5 mph (a fast but comfortable touring speed in the boat I was using) the FrontRower system is 19 percent more efficient than a sliding seat sculling system. (I believe a small part of this is due to the FrontRower's more efficient oar blades; the larger part is probably due to less weight shifting with the FrontRower's fixed seat.)  At other speeds, the results varied.
Compared to paddling
At 4 mph (about as fast as I can paddle for a sustained period of time) the FrontRower system is 20 percent more efficient than a single blade bent shaft paddle.

2. Oar blade size. Contrary to popular belief, bigger is not necessarily better. At higher speeds, smaller is better. The largest blades I tested were 116 square inches. These were the curved “hatchet” type sculling oar blades. The FrontRower's standard blades are 89 square inches and are flat. The hatchet blades were 11 percent more efficient at the slowest speed tested (3 mph). This reverses as speed increases. At 4 mph, the 89 square inch blades were 2 percent more efficient, and at 6 mph the 89 square inch blades were 5 percent more efficient. Even smaller blades (76 square inches) enabled me to sprint faster than either of the larger blades, but were less efficient at cruising speeds. These results lead me to believe that there is probably an optimum size oar blade for every speed.
 
3. Curved blades. I compared the curved hatchet blades to some flat blades of the same size, shape, and weight. The curved blades tested to be slightly more efficient (2 percent) at 3 mph. There was no measurable difference at 4 mph and above.

4. Oar length. The FrontRower's standard oars are 78 inches from the oarlock pivot to the center of pressure of the blade. This is the same as a typical 9-½ foot long sculling oar. I could not find any difference in efficiency when varying the length of the standard oars by plus and minus 6 inches. (It feels a lot different but does not effect the efficiency.)

Details
I conducted my tests at speeds 3, 4, 5 and 6 mph.  3 mph is very slow for rowing and barely gets my heart rate above at-rest, so measuring slower speeds is impractical. Although I am able to sprint my canoe at over 7-½ mph, at above 6 mph it is hard to get my heart rate to stabilize without getting tired or running out of water, so measuring higher speeds is impractical.

The test boat I used was a Wenonah Prism canoe. This is a fast solo canoe 16 ½ feet in length. The standard rowing system was a FrontRower with interchangeable blades. This rowing system is fixed-seat and uses moving pedals for leg power. The standard blade was a flat “broad tulip” shaped blade of 89 square inch surface area.

My GPS reads out in tenths of a mile per hour. My digital heart rate monitor reads out in pulses per minute. It is easy to quickly see which component is more efficient. I repeat tests a number of times to verify the results and average the results to improve accuracy. I have found that the best way to record data is to carry a small tape recorder in my shirt pocket and call out my speed and heart rate every two strokes.
 
To express the difference in efficiency as a percentage of the base, I do this: First, I subtract my at-rest heart rate from all my raw heart rate numbers. This gives me my “effort” heart rate (EHR). Then I use the formula (base EHR – new EHR) x 100 divided by base EHR. The result is the percentage more efficient the new component is over the base component. A negative number would indicate percentage less efficient.