On August 23, 2016, about 1500 eastern daylight time, an experimental amateur-built Searey, N801SR, was substantially damaged during a forced landing, following a total loss of engine power during initial climb from Sebring Regional Airport (SEF), Sebring, Florida. The flight instructor and student pilot sustained serious injuries. Visual meteorological conditions prevailed and no flight plan was filed for the local instructional flight. The airplane was registered to and operated by the student pilot under the provisions of 14 Code of Federal Regulations Part 91.According to the flight instructor, he and the student pilot flew the airplane earlier during the day from Bartow, Florida to Sebring. The airplane was to remain in Sebring for the duration of the instructional lessons. After lunch and a brief overview of the lesson to follow, the flight instructor and student pilot performed another preflight inspection of the airplane and taxied to the runway. Immediately after takeoff, approximately 200 feet above ground level, the engine started running rough and "sputtering." The flight instructor immediately decreased the angle of attack and the engine lost all power. The flight instructor then tried to land on the runway. The airplane landed "hard," slid into an embankment and became airborne briefly before coming to rest. The two-seat, high-wing amphibious airplane, serial number 1MK283, was assembled from a kit in 2001. It was powered by a Rotax 914ULS, 115-horsepower engine, equipped with a three-blade INO propeller. Review of the maintenance records revealed that the most recent annual condition inspection was completed on March 3, 2016. At that time, the total airframe time was 1,058 hours, and the total time for the engine was 358 hours. Examination of the wreckage revealed that the airplane had incurred damage to the fuselage and the left main landing gear had separated from the fuselage. The examination further revealed that the electric turbo control unit had been removed from the airplane. Instead, a manual lever installed the cockpit, operated by the pilot, moved the waste gate open and closed. The manifold air pressure gauge line was disconnected and capped off at the engine; however, the gauge was not marked "inoperative." The tachometer was also inoperative. A small amount of fuel was siphoned out of the main fuel tank and it was observed to be automotive fuel with no water present. There were numerous wires splices behind the instrument panel with different gauge wiring on each wire run. It was noted that the wrong size wire connectors were used on different instruments with the blade type connectors. One ground wire was found off the back of the starter key switch, which was the ground for the master arm solenoid. With this wire off the switch, power from the battery was disconnected from the electrical system. The airplane was secured to a trailer and the engine was started. A magneto check was performed on the engine and both magnetos operated normally. The ground wire was then removed from the back of the starter switch to test the rectifier system on the engine. The engine continued to run without the battery connected to the system as per the manual. The voltage was checked on the output of the rectifier and it was measured to be 12.3 volts. Without the battery connected, the fuel boost pumps, landing gear motor, and the strobe lights would all be placing a load on the rectifier. The normal rectifier output was 13.5 + .2 volts. The engine was shut down with normal procedures.