Access system goes through the motions
  from: Offshore Engineer
  Tuesday, April 29, 2008

An innovative offshore access system has been successfully trialled by the Delft University of Technology’s Ampelmann project team at the Shell-owned offshore wind farm at Egmond aan Zee (Owez).

The Ampelmann method of marine personnel transfer, consisting of a six-legged hydraulic motion compensation platform with a telescoping access bridge mounted on top, is designed to provide safe and easy access to any offshore installation.

Brought to the test stage just a year after it first appeared on a Delft drawing board, the Ampelmann is reported to be attracting considerable interest both within the Dutch offshore industry and among the wider international community. Encouraging feedback last year persuaded DUT to launch Ampelmann as a spin-out limited company, which came into being on 1 January and is tasked with producing the first commercially available units by mid-2008 and delivering the first system to an oil & gas industry or wind energy customer by year-end.

The Ampelmann platform is designed to facilitate safe transfer at open sea from a vessel to any offshore structure, be it a wind turbine or a North Sea platform. According to its developers, since the transfer platform is kept motionless at all times by actively controlling the hydraulic cylinders, the Ampelmann can be used even in rough sea states (up to Hs=2.5m).

‘The technology of this platform is based on a configuration used for flight simulators,’ explains DUT. ‘Instead of creating airplane motions however, its design cancels out the ship motions of a vessel, using a dedicated motion sensor which is constantly measuring the ship motions. From the motionless transfer deck, personnel can safely access any offshore structure through a telescopic access bridge.

‘The successful transfer to one of the wind turbines at Owez proves that there is indeed a ship-based alternative to the helicopter for offshore access,’ adds DUT. ‘And this alternative does not require any adaptation to offshore structures and can be installed plug & play on even small (non DP) vessels.

‘Moreover, the system ultimately resolves the root cause of the marine transfer impasse: providing full motion compensation in all six degrees of freedom.’ OE

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