Lives could be at risk this summer because of failings among the UK's coastguards, rescue co-ordinators have told the BBC.
Most drownings happen in hot weather
Leaked documents from one Maritime Coastguard Agency (MCA) internal report questioned the competency of staff and another admitted the computer system logging incidents was unreliable.
Watch assistants - the most basic rank - have often covered for senior posts.
But the MCA said the country's coastguards were first-class.
Over the last three months, the Real Story programme has obtained leaked emails and internal documents from coastguard staff.
REAL STORY: DANGER ON THE BEACH
Monday, 27 June 2005
BBC ONE, 1900 BST
They paint a shocking picture of staff shortages, inexperience and incompetence.
The findings come a year after a Transport Select Committee accused the MCA, a government-run organisation, of being "entirely complacent" about understaffing.
One confidential report confirmed MCA management was well aware of the problem, admitting it was constantly fighting "a shortfall in competency levels within watches in terms of fully-trained watch officers."
Another document stated: "We have diluted the aggregate competency in our operations rooms. It suggests that our operations rooms are turning into call centres."
Dave Clempson of the Public and Commercial Services Union, the main body representing British Coastguards, showed Real Story evidence that a junior officer acted up as Watch Manager in charge of his station - two ranks above his actual level - on 14 occasions.
This was despite the fact that he had failed his exams and was unqualified to head up a search and rescue operation.
Commenting on the public's safety at sea, Mr Clempson said: "We do preach the safety message but at the end of the day we can't give them a guarantee that the coastguard rescue centre they are bathing nearby is going to be adequately staffed and qualified."
In 2004 the Transport Select Committee heard evidence that a third of coastguard stations were staffed at or below minimum levels.
Its report highlighted the case of Brian and Pauline Ridley who lost three family members after Brian's fishing boat got into difficulty on Loch Ryan in Stranraer on Scotland's West coast.
Coastguards transmitted incorrect details of the boat's location, delaying the search and rescue by 47 minutes.
The coastguard service was criticised in this incident by the Marine Accident Investigation Branch because the station involved in co-ordinating the rescue attempt - in Clyde - was running below minimum staffing levels and three people were acting above their rank.
Brian's wife, Pauline, told Real Story: "It was nine months after when I found out the truth of the wrong co-ordinates that had been given. I was devastated."
Brian Ridley recalled how he lost contact with his son and grandson after his boat sank while waiting for the rescue to arrive.
"Shaun and the kids were just drifting away with the tide and he just turned around and shouted 'I can't help you, Dad' and those are the last words he ever spoke."
Coastguards are also concerned about failings in the computer database known as the Incident Management System (IMS) - which is used to log incidents coming in.
One officer told Real Story: "Never once have I gone on duty where there has not been at least one major fault on the go."
A fault log leaked to the BBC shows that on several occasions this year live incidents have disappeared off the system, others have not been logged and warnings were not passed on. Coastguards describe some of the failings as "critical" and "repetitive critical".
The MCA says coastguards' skills are constantly developed
From other leaked MCA documents, it appears that managers privately accept the computer is unreliable.
One report from the MCA in the West of England admits: "The whole system is unreliable and does not allow the extraction of essential data."
However, Head of the MCA, John Astbury, did not accept the criticism.
"I have just been round the coast and I always ask the question, 'How is your IMS system?' and they always say to me 'It's OK, boss. It's fine.'
"The idea that it prevents people co-ordinating incidents is nonsense."
Mr Astbury admitted the coastguard system had to react to the increasing number of Britons going out to sea for leisure.
"We are not perfect. We keep changing and evolving - but we do listen to what's going on and we are a first-class organisation."
Real Story: Danger on the beach - BBC ONE, Monday 27 June, 2005 at 1900 BST.