A man relived the moment he was sure he was about to die, as a speedboat propeller blade sliced across his body and severed his friend's hand.

Michael Tierney told of the moment he realised his friend Ian Langan was dead when the man's hand fell on him.

Mr Tierney still walks on crutches more than a year after the boat crash which broke his left leg and ribs and killed Mr Langan.

Their boat, called Seadoo, was hit by a powerboat, Blue Sunset, driven by Mr Langan's younger brother Cliff, just south of Brighton's Palace Pier on August 4 last year.

Mr Tierney, of Kings Langley, Hertfordshire, told an inquest yesterday: "I knew I had been hit and I thought that was the end.

"I was just aware the propellers were coming through us. I got a couple of swipes of the propeller blade and then suddenly it was quiet. The noise had stopped and I couldn't believe I was still there.

"I knew Ian was dead when his severed hand fell off my shoulder."

Earlier yesterday, collision investigations expert Julian Happian-Smith had placed the blame for the accident on both Cliff Langan and Glen Mackay, who was driving the boat which was hit.

Mr Happian-Smith said they both showed "poor seamanship" by driving after drinking alcohol and not paying enough attention to where each boat was.

Ian Langan, 45, of Springfield Road, Brighton, was killed almost instantly by the collision, at about 6.50pm.

As well as his broken bones, Mr Tierney suffered internal bleeding but said he would have died had he not managed to shift his body just in time.

He said: "I saw both boats were coming together slowly then the other boat seemed to be speeding up.

"With about 50 yards between us and about five seconds to go, I thought we were in absolutely no danger. There was plenty of time for it to stop.

"Then we started to panic. In that position my skipper should be aware of the other boat and ready to take action but the other boat should give way.

"I realised the boat was coming straight at me, not just our boat. There was no way of avoiding this. I just managed to get my vital organs in front of the prow but I wasn't able to move my lower body and ribcage out of the way.

"Ian was just behind me and he didn't have the little option I had."

The boats had originally left from Brighton Marina, where the party of seven had gathered after meeting in Hanrahans bar.

On board the Seadoo were the boat's owner Mr Mackay, from Brighton Marina, Ian Langan, Mr Tierney and Stephen Trigwell, from Brighton.

Bernard Rogers, from Dartford Kent, and owner of the Blue Sunset, was accompanied by his partner Jeanette King and Cliff Langan, of Neptune Court, Brighton Marina.

Mr Rogers was initially at the helm but handed over to Mr Langan as they left the marina and headed towards the Palace Pier.

Mr Tierney said both boats were travelling "bloody fast", about 50mph, after leaving the marina but Seadoo had slowed down after both had completed a 360-degree loop shortly before the crash.

He added that he and Mr Trigwell had only had one alcoholic drink each, after spending the afternoon at a classic car show near Worthing.

He at first assumed all seven would be travelling on Mr Mackay's recently-purchased boat.

He said: "I really wish we had stuck to that plan now."

Mr Rogers and Ms King told the inquest they had travelled about as far as the West Pier before starting to turn back, just before the collision.

They and Mr Tierney denied earlier witness suggestions that the boats were travelling at least twice the marina speed limit of five knots and indulging in "showboating" manoeuvres.

The inquest had earlier heard that Cliff Langan had drunk between three and four pints of lager before taking to the water, then drunk from cans of Stella Artois while aboard the Blue Sunset.

When interviewed by police, Mr Mackay said he had drunk between three and four pints of ale in Hanrahans, as well as some ginger wine.

However, he insisted he had been driving responsibly.

He said he could not confirm witness reports that he had performed 360-degree turns while in the marina but acknowledged he may have done to show the boat's capabilities.

He said: "At all times I was aware of boats around me up until the time I last looked at the boat that hit me.

"I was being vigilant but the boat was so far behind me and I dismissed it. I didn't expect it in such a short space of time to be on top of us.

"I don't know where it came from. It happened in a split second, it was a million to one chance we crashed."

He estimated he had dropped to between 15 and 20mph at the time of the accident, while the Blue Sunset was travelling at about twice that.

Mr Happian-Smith, a consultant engineer to the Transport Research Laboratory, said: "The prime cause of the accident was the poor seamanship on the part of both drivers.

"Having taken alcohol before going to sea is poor seamanship. They were taking upon themselves the responsibility of having reduced response and recognition times to obstacles or potential dangers. It doesn't appear the helmsmen showed sufficient awareness of where the other boat was."

Mr Mackay and Mr Langan were both arrested following the accident but later released without charge.

Mr Langan told the inquest on Monday he felt he was steering sensibly and had his vision of the other boat obstructed by the Blue Sunset's bow, until it was too late.

The hearing, before a jury of eleven at Brighton magistrates' court, is expected to last until Thursday.