Scale Factor calibration

Step 1. Place the paddle onto the calibration jig (right blade)

  • Place the paddle onto the calibration jig with the right blade on to the Blade Support

  • The blade should be supported near its centre

  • The shaft support should be approximately at the top hand position

Step 2. Measure and enter distances into the calibration spreadsheet

  • Tip to blade support: The distance from the right blade tip to the centre of the blade support.

  • Tip to shaft support: The distance from the right blade tip to the centre of the shaft support.

  • Tip to calibration weight: The distance from the right blade tip to the position where the calibration weight will be applied. It is helpful to mark this location with masking tape so when it comes time to applying the calibration weight you can hang the weight in the correct location

Step 3. Record the zero-load outputs

With the paddle in position, but without any load applied, open the Calibration page of the Web Bluetooth App and record the right shaft live outputs A and B, the left shaft live output C and both left and right shaft angles in the first row of the Scale Factor Spreadsheet.

Step 4. Apply weight to the shaft

  • Hang a calibration weight off the shaft at the location measured in Step 2.

  • Record the live outputs of the right shaft A and B channel, the C channel of the left shaft and shaft angles in the second row of the spreadsheet.

  • Enter the mass of the applied weight into the spreadsheet. Don't forget to include the weight of the rope, hook or bucket used to suspend the weight.

  • Add another calibration weight to increase the load applied to the paddle. Repeat the steps above recording the live output, angle and calibration weight in a new row of the spreadsheet. The spreadsheet allows for 2, 4 or 6 point calibrations. Ensure the position of the calibration weight, the blade support and the shaft support remain the same for each point in the calibration process.

Step 5. Remove the calibration weights

Step 6. Measure and enter datum distances

Remove the paddle from the jig and without altering the length of the paddle, measure the datum distances and enter these into the calibration spreadsheet.

  • Tip to datum: The distance from the right blade tip to the right shaft datum mark

  • Datum to datum: The distance between the datum mark on the right shaft and the datum mark on the left shaft. If you find it difficult to measure this distance, you will find it easier with the paddle set to the same length, but with a 0° offset

Step 7. Enter the datum to Gage distances

Enter the Datum to Gage distances into the spreadsheet

  • Tip to Blade Gage = 0.28m

  • Tip to Centre Gage = 0.1m

  • Tip to Extra Gage = 0.06m

Note that some Whitewater Slalom shafts have custom Datum to Gage distances. If you have a Whitewater Slalom Kayak Power Meter, please get in touch with One Giant Leap to get confirmation of your Datum to Gage distances.

Step 8. Calibrate the left shaft

Place the paddle onto the calibration jig with the left blade on the blade support and repeat steps 1 to 7, this time completing the ‘Left Shaft’ section of the spreadsheet.

Step 9. Retrieve the Scale Factors from the spreadsheet

  • The Scale Factors for each channel are shown in the plots of the calibration spreadsheet (see example below):

e.g. y = 0.1747x indicates the Scale Factor is 0.175

Note that the C channel scale factor of the left shaft is shown alongside the A and B channel scale factors of the right shaft.

The R^2 value should be close to 1. This indicates a good calibration.

Step 10. Set the Scale Factors

  • Navigate to the Calibration page of the Web Bluetooth app and connect to the power meter

  • Open the Web Bluetooth App, connect to the Power Meter and navigate to the calibration page

  • Set the scale factors by clicking on the scale factors and enter the values. The Scale Factors should be multiplied by 1000 before being entered into the app. For example, if the Scale Factor is 0.1747, then the value '175' should be entered into the app. This value has been rounded up to three significant figures and does not include any decimal places