An Australian girl criticised over her bid to sail solo round the world said on Wednesday her yacht had been fitted with an ear-splitting new alarm to stop her crashing again.

Jessica Watson, 16, said her pink yacht had been modified since it was badly damaged in a collision with a 63,000-tonne cargo ship just hours into a test run.

Maritime officials have said Watson, who will sleep in 20-minute bursts during the eight-month voyage, probably ''dozed off'' before the crash.

- I suppose one big thing is that really loud alarm we've got now so there's absolutely no chance of me missing the warning alarm of a ship approaching - she said.

- It's quite something actually, it hurts your ears - she said.

She said she had never considered abandoning her bid to become the youngest solo round-the-world sailor despite calls from Australian authorities to give up on the 23,000 nautical mile journey.

- To be honest it never even crossed my head," she told reporters in Sydney.

Jessica's safety guide consisted of a page torn from a school notebook

- I never even thought once that I didn't even want to do this. It's never, ever been like that for me - she said.

Last month's accident snapped the mast of her 10-metre (33-foot) yacht, Ella's Pink Lady, which was ''extremely fortunate'' to stay afloat, according to transport safety officials.

They also said the teenager did not have a fatigue management plan and her safety guide consisted of a page torn from a school notebook which was covered in childish doodles.

- There are people out there who I suppose have their doubts, and rightly so because it's a big, scary and possibly dangerous thing, but I am not here without confidence - Watson said.

The teenager's route will take her north from Sydney to the equator above New Zealand, around South America's treacherous Cape Horn before winding back via the Southern Atlantic and the Cape of Good Hope.

Watson, who is set to leave Sydney within days, hopes to beat the record set by fellow Australian Jesse Martin who completed the journey aged 18 in 1999.

In August, a Dutch court ruled 13-year-old Laura Dekkers could not embark on a solo round-the-world voyage and placed her in the care of social services.

Asked how she would cope with big waves, Watson said: ''Just up and over really.''