Hoverline International (HLI) is about to start its first contract to provide offshore crew transfer by hovercraft. The service will ferry personnel to and from offshore platforms from a Petrobras base in Aracaju in northeast Brazil.
The contract, to which HLI’s Brazilian subsidiary Hoverline Offshore Brazil is also party, was signed in November last year. It is valued at SEK 173 million ($24.55 million) for the firm period of four years, with options for a further three years.
The company has deployed the hovercraftEagle for this job, says Peder Silfverhjelm, CEO of Hoverline Group. The craft is a PAP1-300 unit built in Australia in 1987 under license from the UK’s Hoverworks. It underwent a complete refit, including a change-out of engines, propellers, and electronics, in Singapore before being transported to Aracaju.
TheEagle hovercraft approaches landfall in Aracaju.
For a trial periodEagle will work on its own. Petrobras operates around a dozen platforms employing 1,700 offshore staff out of Aracaju; when the company gives the green light for the full service, Hoverline expects to bring in a further two hovercrafts.
The Hoverline service will bring clear benefits to Petrobras compared with the supply vessels and helicopters currently used, says Silfverhjelm. While supply ships must make a journey of over 30 nautical miles (60 km) lasting two and a half to three hours, the hovercraft’s route is only 11 nautical miles (20 km), which it can cover in 15 minutes. Travel by hovercraft is also less fatiguing for the crew, leaving them more time for useful work.
Helicopters cannot compete with hovercraft due to their high cost, limited capacity (half a dozen passengers) and much greater need for logistical and maintenance support. The hovercraft is also safer.
Shallow-water benefits
As a hovercraft cannot operate in sea states with wave heights of more than 2 m (6 1/2 ft), operations are restricted to the more benign areas. But there are also conditions which hovercrafts are better suited to tackle than ships, such as very shallow waters and waters that become ice-covered in winter. For this reason, they are used by Shell, for example, in the shallow waters of the Niger delta, and by Eni in the shallow waters off Kazakhstan in the Caspian Sea, which ice up in the winter months.
For crew transfer, hovercrafts have a competitive edge over ships in several ways. Power ratio is one. This stems from the very different displacements of the two modes of transport - while a ship has a displacement of several thousand tons, a hovercraft displaces about 30 metric tons (33 tons). While a ship has to move about 1 metric ton (1.1 ton) to transport one passenger, the equivalent for a hovercraft is about 250 kg (551 lb), says Silfverhjelm.
Where a ship requires propulsion by diesel engines of 6,000-10,000 hp, a hovercraft needs only diesel engines of 3,000 hp. This means that its fuel consumption is much less than that of a ship, as are the emissions of waste gases. The hovercraft also requires only a two-man crew.
Assuming operators decide to take advantage of the benefits of crew transfer by hovercraft, Hoverline plans to introduce specially designed hovercrafts with crew transfer units (CTUs). These craft have been designed with a payload of 25 metric tons (27.5 tons), allowing them to carry some freight, such as spare parts in addition to passengers.
Eagle which has a payload of 15 metric tons (16.5 tons), has been configured to take 60 passengers and a small amount of equipment.
It has been fitted with a gangway based on hydraulic ramp technology. Once deployed at the platform, the gangway is held in position by electronic magnets. If these fail, hydraulic valves automatically secure the gangway. This is a safer and more efficient solution than transfer by crew basket or by line as on a ship. The hovercraft also provides a much more stable platform during transfer, remaining steady on its air cushion in contrast with a ship, which pitches and rolls in the waves.
There are also various environmental benefits. For example, there is no negative effect on marine life because of propeller noise. That noise is not transferred into the sea and no underwater turbulence is caused. There is no discharge of diesel fuel or lubrication oil into the sea. Recent developments in propeller design also have reduced substantially the noise that characterized the early hovercraft.
Maintenance requirements also are met. No special facility or dock is required; maintenance and run-of-the-mill repairs can be carried out on the beach.
The support structure required by hovercraft is much less than that for ships or helicopters, making it suitable for operations in remote areas lacking infrastructure, Silfverhjelm says.
Operators have responded to the benefits of using hovercraft offshore. Hoverline, which has concentrated its marketing on the key offshore provinces of West Africa and Brazil, also has received inquiries from companies interested in operating diverse areas, including the Indian, Saudi, and western Canadian offshore.
Petrobras has shown interest in possibly contracting further services from Hoverline. This year Hoverline will also carry out a feasibility study on behalf of several oil companies.
Rather than develop a tailor-made service for each customer, the aim is to produce a standard model that only needs fine tuning for specific applications, Silfverhjelm says.
The company has set up a division under the trademark Logistic Extreme to handle its operations offshore and in remote areas lacking in infrastructure.
For more information, contact Peder Silfverhjelm, Hoverline. Tel +46 703 591 501, fax +46 8 545 896 49.[email protected], www.hoverline.se
