a watercraft has an overturn detector . the detector communicates with a controller to prevent a false overturn signal . the controller does not act on overturn signals when the watercraft is operating above a preset engine speed associated with planning mode . the controller stops the engine when the overturn signal persists for longer than a predetermined period of time while the engine is operating below the preset engine speed . the controller also monitors the overturn detector for failure . in the event of a failure during engine starting , the engine is allowed to run while the operator is alerted . in the event of a failure during engine operation , the engine is stopped and the operator is alerted if the watercraft is not in planing mode . if the failure during engine operation occurs when the watercraft is in planing mode , the operator is alerted but the engine is not stopped .