Terry Gilmore, senior yacht-staff trainer, tosses some striped cushions from the white canvas sofa and drops several blue monogrammed towels on the scrubbed wooden foredeck of the Latitude superyacht. He watches as his trainees hasten to restore order.

"What do we always ensure?" he snaps, looking with irritation at the new arrangement then answering his own question: "That the zip is down."

The crew is not seen or heard. We're like rats, I suppose. Just stowed away

He rotates several cushions to conceal barely visible zips. In any case, it turns out that the towels should be picked up first, so that they do not soak dampness into the sofas, and the lesson proceeds with detailed instructions on the correct method for rolling a towel, so that the monogram is prominently displayed (not easy).

"Not like that; totally wrong," he tells a trainee, pointing out in passing that his belt is too long and the creases on his polo shirt are insufficiently sharp.

As the global economy struggles with the fallout from recession, the lives of the super-rich continue largely unruffled by the constraints of the downturn. And there are few starker examples of pure extravagance than the superyacht. A luxury yacht (unlike a house in London's exclusive Knightsbridge, say) is less an investment than a bottomless pit to throw money at and it follows that the owners of superyachts are not people who worry much about penny pinching. They are people who are used to getting what they want and, as employers, they tend to be extremely exacting.

The expanding ranks of billionaires worldwide are creating a new job market for servants, often providing the most esoteric of services. The people who staff superyachts need to be equipped with discretion, servility and good ironing skills, and are relatively well-paid for their work (salaries start at between HK$17,000 and HK$25,000 a month, including a berth on the yacht and all meals, and rising to HK$40,000 a month for more senior staff).

Sara Vestin Rahmani, founder of London-based Bespoke Bureau, a high-end domestic staff recruitment agency, has this year launched a yacht-staff training course in Antibes, in Provence, France, with the firm Abacus & March, after identifying demand from her clients for well-trained staff capable of working on board superyachts (the term for a yacht more than 164 feet long, vessels which usually sell for anything between HK$350 million and HK$700 million). Vestin Rahmani's placement agency has thrived and expanded throughout the economic downturn and she is also running butlering courses in Norfolk, in eastern England, for the European market, and in Chengdu, Sichuan province, for her clients in Asia.

"We're lucky in the sense that the rich get richer in a recession," she says. "Hong Kong and the south of China is always an interesting place for us to place staff; the climate, the respectful culture, the decadence, the high salaries and the interest in our British staffing culture. We train and place yacht crew for Chinese high-net-worth private clients and also for yacht-management companies that hire out staff to the yachts. The highest paid yacht placement was for a £150,500 [HK$1.76 million] yearly salary in China."

On board Latitude, a vessel occasionally chartered by musicians such as singer Rihanna, trainees are being instructed in the arts of humility and occasional invisibility - both of which should make them attractive to superyacht owners.

Gilmore has spent a career serving members of the Saudi royal family and rich Russians on board their yachts and is well qualified to pass on his expertise; his fellow trainers have worked on vessels owned by Roman Abramovich, the Russian oligarch and owner of Chelsea Football Club, and the Emir of Qatar. Students have paid €900 (HK$9,000) for the week's course, hopeful that it will help them secure a job on board one of the world's superyachts. In the abstract, the work seems steeped in glamour, but Gilmore is at pains to disabuse his trainees of any starry-eyed notions about the role. A couple of days on Gilmore's training programme stamps out any lingering sense that this might be a desirable job. Staff need to understand they will simply be "glorified cleaners", he tells them.

Trainees must memorise correct forms of address from a training manual, which informs them that it is unacceptable to ask "Why?" ("May I know the reason?" is the stipulated locution). The inquiry "Are you done?" should be replaced with "May I ask if you have finished?"

Trainees are told that some guests may request that they stand silently on board deck, motionless in the sunshine, waiting for instructions. "It's stupid, because they could use a buzzer," Gilmore says, but much of the staffing on yacht businesses is about ostentation, and if a motionless steward standing by on deck is what the owner requests, then staff are not to argue.

He tells trainees they must never wear sunglasses while addressing guests on board a yacht, because guests want to be able to see their eyes.

"Never stand there and tell them your life story. Never interrupt the guest. Never ask them personal questions," he says. "Just say, 'Good morning, sir.' Don't ignore them, but don't engage."

A daily list of housekeeping tasks includes polishing the television remote control and checking the towels for stray threads, which need to be chopped off with nail scissors. Students learn that they must monitor the bathrooms and lavatories, and are given guidance on the correct amount of time they should leave before scurrying in and tidying up after a guest, which involves refolding the end of the loo paper into a pointed V. "Be aware when people have used the rest rooms. You must be their shadow, but not too close," Gilmore explains.

The trainees write notes diligently in their notebooks as Gilmore tells them to check the contents of the yacht's sun-cream bottles daily. "If they are less than half full, you can't have that because it looks cheap." The bottles that have dropped beneath the 50 per cent mark are discarded. He claims the last yacht he worked on had an annual budget of about HK$60,000 for sun cream alone.

To own a superyacht such as this one, you need to have a serious chunk of disposable income. If you had a net worth of about HK$1 billion, you would probably be too poor to contemplate taking on the considerable outgoings that staffing and maintaining this kind of extravagance entails. Although some of these vessels exist to be chartered out as a business (at about HK$2.5 million a week), they rarely make money for their owners this way, once annual docking, licence and engineering costs are factored in. Merely transporting your yacht from the Mediterranean to the Caribbean on a container vessel for the winter season (to avoid damaging it en route) costs about HK$3 million.

Despite the expense, though, the superyacht market is expanding. There are 400 new superyachts under construction (and unlike cars, old yachts are repaired rather than scrapped, so this represents an increase in the absolute numbers), which will create work for an estimated 3,500 new crew. At the extreme end of the market, the superyacht is no longer a particularly ostentatious purchase. Three years ago, Abramovich took delivery of the Eclipse, a 536-foot gigayacht (considerably larger than a super- or megayacht), but even this massive liner has subsequently been shunted into second position by the Azzam, at 590 feet currently ranked as the world's largest private yacht.

Working for billionaires comes with unique complications. "The security implications are horrendous. Most of the people who own these boats are people who are security targets - royal family, politicians," Gilmore explains, warning his students that pictures taken on board should never be uploaded on to Facebook or Twitter, to avoid exposing the yacht's owners to security breaches or embarrassment.

Crew members' mobile phones must always be left downstairs, in their minute cabins. Gilmore relates an alarming story of a junior steward who was serving dinner to guests when her phone rang in her pocket. She was lucky not to lose her job, he says. He tells another cautionary tale of a junior crew member who put a guest's HK$9,000 cashmere jumper into the dryer, shrank it to the size of a doll's jumper, pressed it, wrapped it in tissue paper (standard presentation for newly laundered clothes) and returned it to the guest's cabin. She, too, was lucky not to lose her job, although this revelation is greeted with aghast horror by a fellow trainer observing the session, who declares that she would have sacked her.

Very little attention is paid to employment law by yacht owners, partly because of the international nature of the operation; crew members can be fired on a whim.

"You might have an Egyptian owner, a boat registered in the Cayman Islands, based in Monaco, a company registered in Germany, a crew made up of Australians and South Africans. Where are the social security payments made?" says a representative of an international yacht association that offers support to yacht staff, asking not to be named. "This is probably the most politically incorrect industry in the world. You can get fired because you are not blonde or pretty. It is all about the look and the image."

Because of concerns over workers' rights, the International Maritime Organisation has recently drawn up the Maritime Labour Convention, which should be introduced from next month and will ensure that crew get three meals a day and proper breaks. Attempts to introduce regulations aimed at improving the size of crew quarters had to be abandoned, however; larger crew cabins would have cut into the yacht owners' living space.

"Eight guest cabins would have gone down to four cabins. People wouldn't have wanted to own yachts. It would have made the industry obsolete," says the woman from the yacht association.

Much time is spent discussing the trainees' personal appearance; they are told to make sure they smell fresh, that they should clean their teeth after drinking coffee and should be clean-shaven. "That's for girls as well as boys. It's not nice if you are having breakfast to see a girl's hairy legs," says Gilmore. No nail polish is allowed, in case it chips off in the food. He also warns new recruits that they should be on their guard when the weather turns bad. "If the sun shines, everyone is happy. If not, they start nitpicking. They will start looking for fault. That's when you get aggro."

Many of the skills the students learn here could be transferred to work in a domestic setting, Vestin Rahmani says, and over the weekend visit she is also scouting for butler talent for her London business. She is seeing a rising demand for butlers, she says, and her experience chimes with recent research indicating that there are more servants in Mayfair now than there were 200 years ago, with entourages stretching to maids, part-time chefs, part-time drivers and personal assistants.

The job specifications on recruitment sites such as Vestin Rahmani's give an insight into the lives of prospective employers, who hope their staff will have everything from "a high level of technological knowledge and ability to deal with complex electronic control systems for house-hold security systems", to experience in maintaining media rooms and orangeries.

A good butler in London can expect to earn well over £50,000, but many are paid more; she acknowledges that it is sometimes hard for her richer clients to keep a handle on what average salaries are.

"I have a lot of Middle Eastern and Russian clients who are hiring butlers. Sometimes it's a statement. It says: 'I have a lot of money, and now I have a butler.' And then there are some people who genuinely need a butler.

She appreciates that working for this kind of employer can be challenging. Recently, she heard of two yacht stewardesses who jumped into a jellyfish-infested patch of sea to create a clear swimming channel for one of the boat's guests. "She was really in the mood to go swimming, so they swam alongside her - they wanted to make sure she didn't get stung. They got stung to bits and were in a bit of pain the next day. That's sweet, I think. They got a big tip at the end of the week," she says.

"Chinese students are great butlers and yacht workers because of their discreet nature and humble personalities," says Vestin Rahmani. "Chinese students get trained in China or they fly to us [in Britain] and join the one- and two-week programmes to work as a butler or yacht interior crew."

The woman from the yachting association relates the story of a flatmate who worked for Abramovich's first wife, who liked a particular kind of home-made chocolate on board her yacht. Even if her flatmate was busy, she was often asked to make an 80-kilometre round trip to Monaco to buy the chocolates from the only supplier. "I wonder, if they knew the trouble it caused, whether they wouldn't say: 'Actually, don't bother; take the morning off.' The chocolates were divine, but they could have had other chocolates," she says.

Gilmore, 63, retired last year, after 40 years working on yachts, because he was exhausted. "It is a tiring job, keeping these people happy," he says. "It is not a family friendly business. These people, they like you, but they don't like baggage.

"Inevitably there are going to be people you won't choose to get on with in life, but it's all about respect," he says. Part of the course is dedicated to helping staff understand how to react to bullying from their employers. "They can order you in a way you are not used to," he says. "You train people to respond to that kind of abuse. You stand there and let it go in one ear and out of the other."

Sexual harassment is uncommon (because the relatively confined space on a yacht inhibits it), but not unheard of. Gilmore discusses what to do if an owner pinches a member of staff on the bottom. "Slap him and you've lost your job," he points out, advising trainees to remain silent and report the incident to a superior.

In the afternoon, trainees are sent to a villa a few miles inland from Antibes, where they are taught to make beds, given ironing training, drilled in laying the tables swiftly for 12 guests, and finally practise serving champagne to their trainers (who seem to enjoy the session).

Gilmore is phlegmatic about the joys of yacht ownership: "Personally, I would never own a yacht, even if I had all the money in the world. It is a bottomless pit; you're always putting money into it."

Gary Robson, a recruitment consultant for Abacus & March, is still unsettled by the amount of money he encountered during his career as a chief steward, working first for a Saudi Arabian construction magnate and later for a Russian oil oligarch and then a Chinese billionaire who had made his money from casinos and property.

"I'd never met that kind of money before. We are talking the billions. What do you have to do to earn this kind of money? I don't know what is happening to society, but there is such a big divide," he says during a break from training. Occasionally, the extravagance he witnessed on board overwhelmed him. "They would say to me, there will be 15 to 20 guests. Everything would be prepped and done - lobster and caviar - and then there are just two people for dinner and it's all wasted. I think some of them have lost their understanding of what it actually is, money. Money, to them, is not what it is to you and me.

"Some of them are not even very keen on yachts. They get seasick. You wonder, 'Why do they buy them?' Keeping up with the Joneses?"

The yachts' designs reinforce the division between owner and staff, he says. "The crew is not seen or heard. We're like rats, I suppose. Just stowed away. I have had some really nice owners and some who are totally the opposite. It's nice when you get owners who say hello to the crew. Some are rude; grunt or wave; no eye contact."

Occasionally, the exposure to this level of wealth rubs off on the staff, who find themselves infected with the big-spender mentality, he says. He recalls nights out where he ordered Dom Perignon (which you can buy for HK$800 in a shop) for HK$3,000 to HK$5,000 in a bar.

Most of the trainees are excited about having a chance to work for billionaires. Andrew Drsydale, 28, a former cocktail waiter from Newcastle, northern England, has been in Antibes for several weeks, looking for yacht work. "I wouldn't think of myself as a servant," he says; instead, he hopes the work will become a long-term career. "I'd like to be working for someone who wants excellence in their service, in their drinks and food. You want them to care. It's the appreciation of your work you want," he says.

He doesn't find the extremes of wealth demonstrated in the yacht industry disconcerting. "You can't even be jealous because it is so out of reach that you are never going to come into it. It doesn't upset me."

Pavleta Hristova, 28, a qualified dentist from Bulgaria, hopes to find work on a yacht because she has not found work at home in her own profession. She would like to join her husband, Anton Hristov, 32, who has been working for a number of years on cruise ships and has recently shifted to yacht work. The couple listen attentively to Gilmore's instruc-tions on silver-service table arrangements, and race obediently to lay an outside table for six people, for a three-course (imaginary) dinner of salad, veal and souffle.

Hristov likes what he has seen of the yacht world. "These people don't think twice about how they spend their money. If you can afford to have a yacht, why not? People like to have fun and enjoy their privacy."

Max Hinton, 19, from the southern English county of Kent, has given up his job as assistant manager in a cocktail bar and is paying for the course with his savings. He has been dock-walking for more than a month - pacing the harbours in Antibes, and marinas in neighbouring resorts, before breakfast, with dozens of other prospective crew members, all searching for work - and hopes that the course might improve his employability.

Vestin Rahmani identifies something pleasing in his demeanour - a mix of eagerness to help and a humble reserve - and says she thinks he will go far in the industry. She takes her work very seriously, but manages to maintain a healthy sense of the peculiarities of the niche world that her company caters for. Brought up in Sweden, she has strong feelings about the proper payment of staff, and it took her a while to acclimatise to the growing ranks of the super-rich in London.

"I appreciate that it is a little bit of a weird market. I am so used to it now, but I can see from the outside it sometimes seems a bit weird," she says. "When I first came over from Sweden, I worried that people had so much money. I don't think about it any more. What matters to me is whether or not people are nice."