Knowledge Base

Tag : measurements

The oarlock measures both the angle of the oarlock and the force being applied to the face of the oarlock. These measurements are taken 50 times per second and are then used by the oarlock to calculate per-stroke parameters which are transmitted to the SpeedCoach wirelessly. These measurements are ones that have been proven to be most helpful in evaluating and improving rowing effectiveness:

Measurements
MetricUnitsRangeNotes
Catch Angle Angular Degrees Angle of the oarlock when direction of motion reverses from recovery to drive direction.
Effective Length Angular Degrees Total degrees traversed by the oarlock between the 100N for sculling/200N for sweep slip and wash thresholds.
Finish Angle Angular Degrees Angle of the oarlock when direction of motion reverses from drive to recovery direction
Force Newtons to 1/10 The force applied to the oarlock face averaged over the full stroke.
Max/Peak Force Newtons to 1/10 The maximum force applied to the oarlock face at any point in the stroke.
Peak Force Angle Angular Degrees The degrees of angle at which the peak force occurred in the stroke.
Power Watts to 1/10 The rate of work being output. Power can be increased by doing more work per stroke, or taking more strokes per minute.
Average Power Watts to 1/10 Power per stroke averaged over the entire interval (if using a SpeedCoach). Resetting the clock will reset the average power.
Slip Angular Degrees Angle degrees traversed by the oarlock before the force exceeds 100N for sculling/200N for sweep - a threshold below which the work being done on the oar is doing relatively little to increase the speed of the boat.
Wash Angular Degrees Angle degrees traversed by the oarlock after the force drops below 100N for sculling/200N for sweep – a threshold below which the work being done on the oar is doing relatively little to increase the speed of the boat.
Work Joules to 1/10 The force times the length of the stroke. Work measures the effectiveness of each stroke.
Average Work Joules to 1/10 The average force times the length of the stroke. Work measures the effectiveness of each stroke.
Length Angular Degrees Total degrees traversed by the oarlock between catch and finish.
Effective Length Angular Degrees Total degrees traversed by the oarlock between the 100N for sculling/200N for sweep slip and wash thresholds.

Please also vist our Blog post, It's In The Computer: A No-Nonsense Breakdown of Rowing Tech Jargon for additional information on this topic.

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The magnet plate installed below the oarlock creates a magnetic field which is sensed by a magnetometer inside the oarlock. The calibration routine uses a provided calibration artifact, which is basically a protractor that clips onto the magnet bar, to "teach" the oarlock what it will sense at certain angles, ensuring that it provides measurements that are accurate for your oarlock/pin/rigger setup. Angle is displayed with whole degree resolution and is accurate to +/- 2 degrees.

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The range from an oarlock to paired SpeedCoach is approximately 100ft (30m). Simply hold or mount the SpeedCoach in a nearby motorboat to view oarlock measurements. Because each Oarlock pairs to a single SpeedCoach, you will need a SpeedCoach for each seat you wish to view. We recommend installation of SpeedCoach Surface Mounts in the launch to secure the SpeedCoach units for viewing.

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We have tried to balance viewing flexibility with ease of operation by providing two display modes:

"SKILL" mode offers pre-configured data screens that are fast and easy for athletes to use to focus on particular aspects of the stroke. The preconfigured SKILL screens are CATCH, FINISH, LENGTH, WORK, POWER.

"CLASSIC" display mode offers full flexibility to choose any data in any of the four SpeedCoach windows and is ideal for rowers and coaches who are interested in creating their own preferred combinations. For example, it is possible to see how boat speed is impacted by catch and finish angle. Or, monitor heart rate and power while maintaining rating. In CLASSIC mode you have the option of freezing the top windows to Rate and Split and changing only the bottom two, or allowing all four windows to flex.

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We have put a huge amount of effort into making sure each sensor is accurately calibrated and provides consistent readings in all situations and conditions. We have not yet encountered a situation where the measurements don't make sense.

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At a 2:30 you are definitely rowing hard enough that you will see slip and wash numbers that are reflective of your technique, and respond to changes in a relevant way. Your "wash" arc degrees below 100N are likely to be greater than a tall heavyweight sculler's, but reducing the value will indicate a more effective finish.

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