A rowing oar is described. The rowing oar can have a plurality of flow disrupters arranged on a shaft of the oar. In one embodiment, the flow disrupters can be circular bumps arranged in lines along the shaft of the oar. The flow disrupters can cause the air flow over the oar to be more turbulent so that the flow separation on a backside of the oar is reduced. The reduction in flow separation can reduce aerodynamic drag on the oar when it travels through the air. Thus, a rower can expend less energy during rowing using the oar.