The main reason has been the absence of software systems that allow individual calls to be accounted for. And without a means to charge on to individuals, expensive satellite time has been guarded jealously.

But this year's launch of Inmarsat's Fleet F77 is set to revolutionise the way passengers and crew on board large leisure and charter yachts interact with satellite communications systems, opening up email and Internet facilities that historically have been the sole preserve of captains and owners.

The benefits to ship owners and charter firms in terms of new revenue streams will be huge and will lead to the "office-on-the-ocean" technology becoming commonplace on motor yachts and an absolute necessity for anything as large as a superyacht.

Many large yachts currently utilise Inmarsat B with its 64 kbps high-speed data (HSD) service to update weather charts and deliver a plethora of services, such as e-mail, Internet, advanced telemedicine and even video conferencing.

Nevertheless, due to the cost of satellite airtime, even in the lucrative charter market, these services are almost always exclusively for the use of those who pay the bills rather than everyone onboard.

The Fleet F77 terminals are both smaller and cheaper than Bs, making them more suitable for medium sized motor yachts, pleasure craft and superyachts.

Furthermore, accounting products such as IP Communication Gateway, from the Epsom, Surrey, based Livewire Digital (www.livewire.co.uk), are making administration for the terminals far simpler, opening the satellite communication network up to charter passengers and crew alike.

This provides a host of benefits to owners who choose to install the equipment, such as additional revenue streams, new charter opportunities and cheaper data costs for essential ship's communications.

Smaller craft will also be able to enjoy the benefits of email and secure Internet access through Inmarsat's Fleet F33 terminals. These smaller units are designed to offer voice and data services to craft that have outgrown the hugely popular Mini M terminals, but do not require the high-speed data capabilities of Fleet F77.

Accounting for the service Historically the problem with opening up satcom communications systems to everyone has centred on properly accounting for the costs.

Previously it has been very difficult to fairly and accurately separate out the costs incurred on essential ship communications from those of passenger data transmissions.

This made it impossible to provide itemised bills to clients.

David Williams, product development manager, Stratos, explains: "With the relatively high cost of satellite communication people have always tried to make data transfer times as short as possible by using sophisticated batching and compressing techniques."

However, he added, this makes it extremely difficult to split out and accurately cost an individual communication or e-mail. Consequently most ships have very tight restrictions on private e-mail and the Internet.

The particular method of sending data in a satellite environment has never helped the accounting issue.

With Inmarsat B or any system that bills by airtime, the most cost-effective method of data transmission is to carefully compress and package data and send it out in a single transaction, say once every three hours. Each call often incurs a minimum charge, thus it is desirable to keep the number of calls to a workable minimum.

Although this produces a highly cost-effective method of data transfer, it does make it virtually impossible to separate out the costs for essential ship data transfers such as weather charts and engine monitoring data, from personal emails and other "leisure" communications.

The advent of Inmarsat's new Fleet F77 service, with its mobile packet data service (MPDS), has given Inmarsat partners the opportunity to address this fundamental issue.

MPDS differs from other Inmarsat services as it is billed on the volume of data transferred rather than on time.

This means that with Fleet 77 it is practical for a yacht to remain permanently online.

The simple change is set to revolutionise ship communications as it allows owners to track each data package and accurately allocate it to an individual account.

This gives owners the power to scrutinise ship communications to assess precise costs associated with particular pieces of equipment or users. It also becomes practical to offer e-mail and Internet access to passengers and crew with minimum administration overheads.

Marco Franken, satellite communications advisor, Siremu, said: "The lack of transparent accounting methods for satellite airtime has held back the proliferation of digital communication onboard pleasure vessels. Passengers should be able to use the Internet, especially in the charter sector."

Onboard computer networks are becoming more common, he said, and satellite terminals have become more affordable, now that accounting products are also appearing there are even fewer reasons not to let passengers and crew get online."

Revenue benefits On vessels with many staff, or a quick rotation of passengers, systems similar to those already used in Internet cafes across the world can be utilised to offer passenger and crew access to email and the Internet, either from a public terminal or from the privacy of their own cabin in large yachts.

This opens up a significant new revenue stream for charter operators.

Simple individual logins allow transactions to be charged on a pre-pay or "on account" basis.

This system leaves control in the hands of the owners, but also lets them offer a customised service to individuals.

To protect against misuse or unexpectedly large bills, credit limits can specified, with certain users given priority or access to more expensive services that are closed to others.

A further benefit of the shift to using Inmarsat terminals for value added leisure services is the potential for reducing a vessel's operating expenses. By sending more data, the cost per byte is reduced through volume discounts, making essential communication cheaper.

Charter passengers The potential for new revenue is greatest in the charter market where the extra services can be billed in the same way telephone calls are from hotel or cruise liners.

In effect this technology allows charter yachts to offer a full "office-on-the-ocean" package to business clients.

Passengers can even connect their own laptop to the vessel's Inmarsat equipment and access e-mail, corporate intranet sites and the Internet, as well as have access to telephone and fax services.

This is a major plus for those business people who are never more than arm's length from their computer and provides innovative yacht owners with a host of new charter opportunities including additional corporate hospitality events and longer cruising routes.

Crew morale With many of the largest superyachts carrying up to 30 crew members, the additional revenue generated from their use of the communication systems is not to be overlooked.

Crew welfare, especially through crew calling, has featured heavily in the press in recent months. The additional communications opportunities that e-mail offers crew members can significantly boost morale and will help owners to retain quality staff.

It will be particularly beneficial to staff who are away from home for a long period of time or whose loved ones live in a different time zone.

Williams commented:

"Accurately accounting for satellite expenses gives the transparency to exactly cost the communications of an individual passenger or crew member. This makes everything much more manageable and gives vessel owners the flexibility to set up prepay accounts for passengers and crew onboard."

Ultimately, he said, this will help with crew retention and morale.

As well as communication with friends and loved ones, crew can now utilise the Internet to keep abreast of news or monitor bank accounts.

Using MPDS, bank account transactions can be viewed at will once they are downloaded giving crew the chance to make online payments and check balances while at sea.

Previously this would have involved a long phone call to an automated banking system with all the associated costs.

Looking to the future The Fleet F77 service already gives yacht owners the opportunity to offer passengers and crew an "always-on" Internet connection and new products are becoming available that allow this to be accurately billed.

Over time this technology will become as commonplace on charter yachts and leisure vessels as the satellite systems themselves, offering passengers and crew a wider range of communication services.

Ship-to-shore communication is changing extremely quickly and the Internet is influencing the types of services on offer.

There is a migration towards IP as the backbone to these services and the MPDS service offered by the Fleet F77 is another step along this path that will change the way communication is viewed on board vessels.

Franken said: "I think the early users of this technology will be the superyacht owners.

They have historically been the first to adopt new technologies and often already have onboard computer networks. However there are also all sorts of opportunities in the charter market."

Future developments in the area will make these systems increasingly vital and present more and more opportunities to include extra value-added services on motor and sailing yachts.

With its close links to Inmarsat, Livewire will continue to provide innovative solutions that further the use of satellite systems and bring user benefits to owners, passengers and crew.