Barwon Heads Airfield has two strips. The main strip is aligned 350/170 degrees, has a level gravel/grass surface and is approximately 760 metres long. The shorter strip is aligned 080/260 degrees, has a grass surface, is approximately 470 metres long and slopes down to the east. When the aircraft arrived in the circuit area the wind was calm. The pilot intended to land into the north but he noted that there were several power chutes operating from that strip so he opted for an approach into the east. The first approach resulted in a go-around due to a power chute landing into the north. This chute was pulled up just prior to the intersection. The second approach resulted in a touchdown which was later measured to be 73 metres in from the threshold markers. Full flap was used. The pilot reported that the aircraft skipped over a small mound at the intersection of the two strips. Braking then seemed to be ineffective. The aircraft felt as though it was skidding. The pilot applied some rudder correction and checked the brakes and hand brake were both off. He said that he then decided to go around but delayed power application due to the proximity of a power chute. Power was then applied and the aircraft became airborne with full flap still selected. It clipped the top strand/strands of a wire fence at the end of the strip. Because the pilot did not know what damage may have been done he closed the throttle and mixture controls and landed beyond the fence. The aircraft touched down, ran through another fence, entered thick tussocks in a swamp and overturned. The investigation found that the short grass strip was wet with dew and had an uneven surface due to cracks in the ground and a tufty grass surface. This would have provided a very poor braking surface. In addition, the strip had an increasing down slope, the last third of its length measured as approximately 3% downhill. The pilot reported that he landed on the same strip the previous week in similar conditions and stopped in about two thirds of the strip length.