On April 19, 2017, about 2045 eastern daylight time, a Cessna 172N, N6013E, was substantially damaged during a forced landing to the Gulf of Mexico near Yankeetown, Florida. The private pilot and passenger were not injured. Visual meteorological conditions prevailed, and no flight plan was filed for the personal flight that was operated under the provisions of 14 Code of Federal Regulations Part 91. The flight originated from George T. Lewis Airport (CDK), Cedar Key, Florida, around 2025 and was destined for Orlando Sanford International Airport (SFB), Orlando, Florida.According to the pilot, prior to the flight he observed 29 gallons of fuel on board the airplane and performed an engine run-up with no anomalies noted. The airplane departed and leveled off about 5,500 ft mean sea level. About 15 minutes after takeoff, the engine "failed" and "violently" shook. The pilot declared an emergency and searched for a place to land. He attempted to restart the engine four times prior to ditching the airplane in the water. The pilot and passenger egressed without injury. According to Federal Aviation Administration records, the airplane was manufactured in 1978. It was equipped with a Lycoming O-320-H2AD, a 160-hp, engine. According to the airframe maintenance logbook, the most recent annual inspection was dated August 27, 2016, at a total time of 10,961.6 hours. The pilot reported that the engine had a total time of 7,378 hours, and 1,299 hours since overhaul. An examination of the airplane revealed that the right wing was substantially damaged. The engine remained attached to the airframe through all engine mounts. Examination of the engine revealed that crankshaft continuity when rotating the propeller by hand. All cylinders remained attached to the engine and were not damaged. Thumb compression was attained on all cylinders when the propeller was rotated by hand. The propeller remained attached to the engine and no damage was noted on the blades. All spark plugs were examined and no anomalies were noted with the electrodes. The oil screen was free of debris. The carburetor was examined, and no anomalies were noted. Fuel consistent with 100 low-lead (LL) aviation fuel was noted in the carburetor bowl, with traces of water. There was no debris noted in the fuel strainer, which also contained 100LL fuel with traces of water. The engine starter operated without anomaly when the key was turned in the ignition. The magnetos were removed, inspected, and were full of water. The magnetos were rotated by hand; however, spark could not be generated. The 2055 recorded weather observation at Crystal River Airport – Captain Tom Davis Field (CGC), Crystal River, Florida, located about 13 nautical miles southeast of the accident location, included wind from 100° at 6 knots, visibility 10 miles, clear skies, temperature 26°C, dew point 13°C, and an altimeter setting of 30.15 inches of mercury. The carburetor icing probability chart from Federal Aviation Administration (FAA) Special Airworthiness Information Bulletin (SAIB): CE-09-35 Carburetor Icing Prevention, June 30, 2009, showed a probability of serious icing at glide power at the temperature and dew point reported at the time of the accident.