On March 13, 2003, about 1800 Atlantic standard time, a Beech V35B, N35SR, operated by an individual, as a Title 14 CFR Part 91 personal flight struck a ditch after landing at the Humacao Airport, Humacao, Puerto Rico. Visual meteorological conditions prevailed. An instrument flight rules flight plan was filed. The airplane was substantially damaged. The commercial-rated pilot reported minor injuries, and one passenger reported serious injuries. The flight had departed from the North Perry Airport, Hollywood, Florida at 1015. The pilot reported that he had landed on runway 10, and during the roll out the airplane veered to the left, and impacted with a ditch. According to the pilot's statement, on climbout from North Perry Airport, he had engaged the yaw damper. About 15 miles from his destination airport he started his descent. He stated that on downwind leg he completed a landing check, and he believed the yaw damper was "disengaged," but did not physically check to see that it was disengaged. He said just before touchdown he felt lateral directional movement. On touchdown "there was a left crosswind," and the nose "kicked left a few degrees." He attempted to steer the airplane back to the center of the runway, but the rudder was "locked." At this point the airplane was partially off the runway. He said he "...poked at the yaw damper switch while pressing hard on the right rudder pedal to no avail," and finally departed the left side of the runway. The airplane traveled through some tall weeds, and "dropped into a ditch.