The present invention relates to a method for jacking up a platform or vessel at sea, which platform or vessel is provided with a number of legs which can be lowered to secure contact with the bottom and where the platform furthermore can be jacked up along the legs to a working position where the platform is free of the influence of the waves. Such a platform may, for example, be used for installation of structures at sea, such as, for example, wind power stations, foundations for wind power stations, other kinds of power stations which exploit sun, wind, currents or waves, or other kinds of projects at sea where there is a need for a platform which can be deployed securely on the bottom for a period of time. The fact that the platform or vessel is jacked up on legs with secure contact with the bottom permits vessel movements such as pitch, roll and heave to be almost eliminated. The platform or vessel may furthermore be provided with a crane for carrying out the tasks that are planned.

The actual platform may be a self-powered vessel arranged to be jacked up, it may be a barge or another kind of floating vessel provided with three or more legs for jacking up the platform. The invention further comprises a hydraulic system and devices which can be employed together with the method for jacking up a platform of the said type.

The invention further relates to a type of locking bolt for connecting the hydraulic lifting system with the legs particularly in connection with the jacking process.

The invention further relates to a lubricating system for applying lubricant to several of the movable mechanical components in the hydraulic system with associated devices, particularly locking bolts and those parts which move at the platform's jack-up legs.

The invention particularly relates to a method, systems and devices in connection with a jack- up vessel or platform, which is designed to move quickly into an operative position and which can be quickly put into operation and subsequently quickly brought out of the operative position after the task in question has been completed. Such a vessel will be capable of making effective use of a short weather window for operations, as opposed to heavy crane vessels etc. which take a long time to get into position and are more difficult to put into operation when the weather window is opportune. At a number of locations in the world the weather window is as short as 48-72 hours and it is therefore advantageous to develop a vessel for fast response. This places demands on the mobility of the vessel, but also demands on the system which has to jack the vessel or platform into an operative position. The jack-up operation may also be conducted in several phases, where a preparatory phase is first implemented in which the legs are taken down to the seabed.

Furthermore, a preloading phase is often conducted where a small number of the legs, for example two of four legs, are pushed down, generally diagonally, into the seabed. A preloading phase of this kind may also be carried out several times. A jack-up phase is then conducted where the legs will sink down into the seabed to different degrees depending on the nature of the bottom. When the legs meet sufficiently high resistance, they will be secured and the vessel will be jacked up.

A jack-up vessel of this kind which can exploit a short weather window must, however, be capable of quickly carrying out the actual positioning process as well as jack-up, possibly with preloading etc.

In order to be fast enough, therefore, it is desirable to use new technology rather than solutions known in the prior art which substantially employ toothed racks and pinion gear for moving the legs in a vertical direction. In particular it is desirable to employ a solution which moves the legs in a vertical direction at a relatively high speed. The movement should also be smooth.

Previously known solutions with jack-up platforms often employ triangular legs of built-up framework. The present invention is based on the use of cylindrical legs, even though various other shapes may also be used.

The legs are provided with grip fasteners such as cut-outs, knobs or holes to enable the system and equipment, which have to move the legs in the vertical direction and jack up the vessel, to take a grip of the legs. The grip fasteners are placed or arranged in a row in the vertical direction of each of the legs with a predetermined spacing between each of the grip fasteners. In different embodiments several parallel rows of grip fasteners may be placed or arranged along the leg's

circumference.

Based on the superior requirements for the vessel's operative characteristics, a method is provided for moving the legs in a vertical direction on a vessel with three or more legs as well as jacking up the vessel into an operative position.

The present invention is therefore a method for creating relative vertical movement between legs and vessel on a jack-up vessel for use at sea, which vessel is provided with three or more legs which are moved in the vertical direction relative to the vessel, which legs are provided with a number of grip fasteners in the legs' vertical dimension. The method is characterised in that on the vessel a jack device is arranged at each leg, in which jack device there is provided a first and a second vertically movable lifting frame above each other in the longitudinal direction of the leg, which lifting frames are provided with activatable locking means which can engage with the grip fasteners on the legs, which lifting frames and locking means move in a pattern in order to create a relative vertical movement between legs and vessel.

In different embodiments of the invention the two lifting frames may move substantially simultaneously in opposite directions in the vertical direction and the locking means on the two frames alternate between being in engagement with a selection of the leg's grip fasteners. The relative movement may be entirely simultaneous but this need not be the case. In other cases parts of the movement may be simultaneous and the speed may also be different.

In an embodiment, moreover, the locking means' engagement with the legs' grip fasteners will overlap, with the result that one lifting frame's locking means engage with the leg's grip fasteners before the second lifting frame's locking means engage with the leg's grip fasteners. After both the lifting frames' locking means are in engagement, the first lifting frame's locking means will disengage from the leg's grip fasteners, thereby ensuring that at least one locking frame is engaged with the leg's grip fasteners at any time.

The lifting frames will be able to be controlled in various ways where the two lifting frames may be individually movable or they may be controlled by a common control system.

The locking means may be activated by different factors such as, for example, where the locking means' activation is coordinated with the lifting frame's movement. Furthermore, the locking means' activation may be coordinated with the lifting frame's position or in relation to the lifting frame's position relative to the leg's grip fasteners.

Furthermore, the locking means may be designed so that the locking means on the first locking frame can become engaged before the locking means in the second frame are disengaged while the two locking frames are still moving relative to each other.

In a further embodiment the locking frames' length of travel in the vertical direction along the leg may be equal to or greater than the distance between two succeeding grip fasteners on the legs.

According to the invention a system is further provided for creating relative vertical movement between legs and vessel on a jack-up vessel for use at sea, which vessel is provided with three or more legs which are moved in the vertical direction relative to the vessel, which legs are provided with a number of grip fasteners in the legs' vertical dimension. The system is characterised in that on the vessel a jack device is arranged at each leg, in which jack device there is provided a first and a second vertically movable lifting frame above each other in the longitudinal direction of the leg, which lifting frames are provided with activatable locking means which can engage with the grip fasteners on the legs, where each of the lifting frames is connected with an end of at least one linear motor, which linear motor is connected at the opposite end with the vessel, with the result that the linear motors move each of the lifting frames relative to the vessel. The movement is in the vertical direction, or along the leg's extension and longitudinal direction.

The linear motors may be of different design but it is preferred that the linear motors are hydraulic linear motors. Furthermore, in an embodiment the stroke length of the linear motors is equal to or greater than the distance between two succeeding grip fasteners on the legs.

In the system as in the method, in different embodiments there will be alternatives where the locking means engage with the grip fasteners on the legs when the locking means are activated or the locking means disengage from the grip fasteners on the legs when the locking means are activated.

If the locking means are in the form of cylinders or locking bolts, there could be a risk of one or more of the locking bolts becoming stuck during operation in a position where a locking bolt is in engagement with a grip fastener. For this reason a solution has been provided in accordance with the present invention where the locking means are releasably mounted on the lifting frame, thereby enabling the locking means to be released and replaced if necessary. This can be accomplished by the locking means' housing or attachment frame being releasably connected with the lifting frame, for example by bolt connection, placing it in a groove, flange connection or by other means.

Moreover, in a further solution according to the present invention, a lubricating system is provided on the various movable parts, with the result that the locking means' movement in its housing or holder or frame is lubricated by the said lubricating system, where a pipe connection and pump are provided for bringing lubricant from a lubricant sump to the locations where the lubricant has to be applied. The pump and any valves in connection with the pipe connection will preferably be controlled by a logic control such as a PLS or the like.

An embodiment of the invention will now be illustrated in the attached figures, in which:

Figure 1 illustrates a vessel with four legs, which vessel can be jacked up by means of the present invention.

Figure 2 is a principle drawing of a jack device according to the invention.

Figures 3- 10 depict a work sequence for the jack device as illustrated in figure 2, according to the present invention. Figure 1 illustrates a vessel 1 with four legs 2. The legs 2 are run through the vessel in a duct 4 in each corner. At each leg 2 there is provided a jack device 3 according to the present invention. During transport of the vessel the legs 2 may be lifted into an upper position where the legs' lower end is at the bottom of the vessel (not shown). Furthermore, the legs can be lowered by means of the jack device 3 to a position approximately as shown in figure 1. When the legs 2 meet firm bottom, the legs will cease moving downwards relative to the sea surface and instead the vessel will move upwards relative to the surface, whereupon the vessel is jacked up as a platform.

Figure 2 illustrates in greater detail a jack device 3 according to the present invention. A section of the vessel 1 is illustrated with a part of a leg 2 in a duct 4 through the vessel 1. A jack device 3 is illustrated in greater detail where an upper (first) lifting frame 5 is placed round the leg 2. The lifting frame 5 is connected with the vessel 1 via an upper linear motor 6, depicted here as a hydraulic cylinder, which cylinder can move the lifting frame 5 in a vertical direction along the leg's 2 longitudinal axis.

A lower (second) lifting frame 7 is also illustrated, which, like the lifting frame 5, is placed round the leg 2 and connected with the vessel 1 via a lower linear motor 8 which is also a hydraulic cylinder.

Both the lifting frames are provided with locking means 9 along their

circumference, which locking means 9, 1 1 are arranged and designed so as to enable them to engage with grip fasteners 10 on the legs' 2 circumference. The grip fasteners 10 are illustrated here as openings in the leg 2.

Figures 3-10 further illustrate how the jack device 3 functions in a cycle.

Figure 3 illustrates a starting point where locking means 9 is engaged with the leg 2 in a grip fastener 10. The lifting frame 5 is in the upper position and the lifting frame 7 is in the lower position. Locking means 1 1 is disengaged from the leg 2.

In figure 4 the cylinder 6 moves the lifting frame 5 to the lower position and the leg 2 is pushed in the vertical direction relative to the vessel. This may mean that the vessel moves up if the leg 2 is securely fixed to the bottom or the leg 2 moves down in the water if it is not secured to the bottom. At the same time the cylinder 8 moves the lifting frame 7 to the upper position.

In figure 5 the locking means 1 1 is brought into engagement with the leg in a grip fastener 10. The locking means 9 is still secured. This situation lasts only for a short time.

In figure 6 the locking means 9 is brought out of engagement with the leg 2. In figure 7 the cylinder 6 brings the upper lifting frame 5 to the upper position while at the same time the cylinder 8 brings the lifting frame 7 to the lower position, thereby causing the leg 2 to be displaced relative to the vessel (or vice versa) in the same way as in figure 4.

In figure 8 the locking means 9 is brought into engagement with the leg 2 in a grip fastener 10. The locking means 1 1 is still engaged and in the same way as the situation in figure 5, this situation is short-lived.

In figure 9 the locking means 1 1 is brought out of engagement and a lifting cycle has been completed with the result that the starting point in figure 3 has again been reached.

In figure 10 the cylinder 6 moves the lifting frame 5 to the lower position and the leg 2 is pushed in the vertical direction relative to the vessel. This may mean that the vessel moves up if the leg 2 is securely fixed to the bottom or the leg 2 moves down in the water if it is not secured to the bottom. At the same time the cylinder 8 moves the lifting frame 7 to the upper position. This is similar to the movement in figure 4.