A system for determining the magnitude of force applied to an oar by a rower as the oar is pulled through water includes a deflection sensor and a temperature sensor mounted on an oar shaft to determine deflection and temperature of a portion of the oar shaft during rowing. A processor connected to the deflection sensor and the temperature sensor receives signals indicative of deflection and temperature of the oar shaft and derives a force applied to an oar blade based on the deflection and temperature signals.