The aircraft was departing from Brittas House Airfield in Co. Limerick on a private flight to a destination in the United Kingdom. With normal take-off power applied and the aircraft well established in the take-off run, the Pilot felt that the aircraft was not accelerating as expected. Despite the application of extra power the speed did not increase sufficiently for the take-off to be continued safely. The Pilot attempted to overfly the deep ditch at the departure end of the runway but made contact with fencing posts in the process. The aircraft came to rest at the far boundary hedge of the adjacent field and sustained substantial damage. The Pilot exited the aircraft without injury.