Jack-up

Jack up could be described as a kind of barge that has its own power mechanism and so it does not need to be led by a tug boat. Jack up vessels have four to six legs that are able to move the vessel above the sea level when necessary. However, before placing the vessel in a certain location, the seabed has to be checked and confirmed that it is safe to jacking mechanism. It is possible that seabed conditions are not suitable for the vessel (e.g. there is a slope or a rocky surface) to be located. In such a case the legs could be damaged and balance of the vessel would be affected. To avoid such situations, modern jack up use a dynamic positioning systems to avoid any kinds of accidents, as they could lead to catastrophic results.

Advantages

• Can be used in water depths up to 120 m

• Transit time is reduced i.e. Working time increases in far offshore case

• Comfortable living space for technicians

• More stable than smaller vessel, i.e. possibility of sea sickness decreases

• Possible to perform small and large replacements

• Storage of large parts is possible

Disadvantages

• In some cases it is not possible to access wind turbine directly - still a need to use smaller vessels to access a turbine

• Less flexible then a ship

• More difficult to relocate during bad weather conditions

• Cannot be used when water depth is more then 120 m