Abstract: A control mechanism is provided for a jet propelled watercraft that enables an operator to engage and disengage a braking gate with hand pressure using a lever on the handlebar of the watercraft. Hydrodynamic assist devices are provided to assist the operator during the engagement and disengagement of the brake by counteracting both rejecting forces and retaining forces exerted on the gate by the stream of water ejected from the nozzle of the jet propulsion device. During initial insertion of the gate into the stream of water, a first hydrodynamic assist device counteracts the rejection forces otherwise exerted by the stream of water against a deflecting surface of the gate. After full deployment of the gate within the stream of water, a second hydrodynamic assist device opposes the retaining forces exerted on the gate and reduce the magnitude of the force necessary to be exerted by the operator to move the gate out of the stream of water and disengage the brake.