No. Hydrow's sensors do not require any type of manual calibration in order to report accurate stats. You do not need to calibrate on initial setup and no recalibration should ever be needed though the lifetime of the rower.
If you think your workout stats are being recorded incorrectly or erratically on Hydrow, please contact our Customer Care team and let us know details about the way in which your metrics are wrong. We'll be happy to help you investigate.