A powerboat crewman died in a race on a course which was too short and on which the risks had not been properly assessed, a marine accident report said today.

The Dover Regatta course in which a competitor with limited racing experience suffered fatal injuries in a two-boat collision was congested by the number of vessels taking part, the Marine Accident Investigation Branch (MAIB) report said.

The event, before hundreds of spectators, took place on a "compromised course" under confusing rules and yet had been approved by organisers the Royal Yachting Association (RYA), the MAIB concluded.

A large proportion of untrained and inexperienced competitors were permitted to race in the event in Dover harbour on August 8 last year.

Also, safety lessons identified following an MAIB recommendation made after a June 2005 powerboat accident in Portland Harbour, Dorset, had not been applied effectively across the sport as intended by the RYA council, the MAIB said.

The report said last summer's accident had occurred when one powerboat co-driven by Alex Edmonds, 41, had unintentionally lost control, turned sharply and slowed significantly.

Another powerboat following behind had little opportunity to take avoiding action and struck the side of Mr Edmonds' boat, close to where he was sitting.

He bore much of the force of the impact. His helmet was torn off and he suffered severe injuries to his head and upper body. Despite prompt and extensive medical attention, Mr Edmonds, from Rochester in Kent, could not be saved.

The MAIB said: "The event took place on a foreshortened and compromised course, under confusing rules and without the risks being properly assessed.

"However, it was approved by the RYA and a large proportion of untrained novice and inexperienced competitors were permitted to race. Ultimately, it was the ability of the crews of the two boats that collided which caused the collision.

"However, they were racing under the auspices of an organisation that the investigation concluded had been insufficiently focused on safety, and had not made adequate attempts to control the race, or educate the crews about the risks they faced."

The MAIB report said the RYA had begun its own investigation shortly after the accident. It concluded, among other things, that the course was too small and had too many turns for the number of boats taking part.

The crews' lack of racing experience was not thought to be a contributory factor, the RYA report said.

The MAIB said the RYA council had agreed to take a number of actions to ensure the future safety of events.