On May 27, 1995, about 1015 hours Pacific daylight time, N7996X, a Cessna 172B, operated by the owner/pilot, impacted a fence during landing roll and was substantially damaged on Sinclair Island, Washington. The certified flight instructor and his three passengers were not injured. Visual meteorological conditions prevailed and no flight plan had been filed. The personal flight departed from Auburn, Washington, and was conducted under 14 CFR 91. According to the pilot-in-command, who was seated in the right front seat, the braking action of the airplane was ineffective during landing roll on a 1,500-foot private grass strip. The pilot stated that due to a downwind landing, his touchdown was further down the runway than anticipated. He stated that he applied light braking after touchdown and the brakes locked up due to moisture on the grass left behind by morning ground fog. He released the brakes to maintain aircraft control. As he approached the end of the landing area, the pilot reapplied brakes, but the aircraft continued sliding on the wet grass and impacted a barbed wire fence at the end of the landing area. The aircraft sustained substantial damage to the left wing and left horizontal stabilizer. The pilot stated that there were no mechanical malfunctions with the airplane, and that the braking was ineffective due to the short, wet grass on the runway.