Techniques and devices to assist an offshore unit in going on location and coming off location. A device may include an interface configured to receive a signal indicative of motions of an offshore unit. The device may also include a memory configured to store a set of values corresponding to acceptable motions of the offshore unit, as well as a processor configured to determine if a measured motion of the offshore unit exceeds at least one value of the set of values and generate an indication that going on location by the offshore unit can be undertaken when the processor determines that the measured motion of the offshore unit is less than or equal to the at least one value.

A self-installing offshore platform includes a top deck that supports an offshore facility, a column having a top end and a bottom end, the top end connected to the top deck, the column that supports the top deck to maintain the top deck above water in a water body in both the deployed state and the undeployed state of the self-installing offshore platform, a skirt connected to the bottom end of the column, the skirt residing above a floor of the water body in the undeployed state of the self-installing offshore platform and residing on the floor of the water body in the deployed state of the self-installing offshore platform, and a ballastable float positioned between the top deck and the skirt, the ballastable float floating in the water when the self-installing offshore platform transitions from the undeployed state to the deployed state.

An offshore platform lifting device for lifting operations at sea after sailed to a certain position of a sea surface includes an upper deck, a plurality of upright columns, a rail seat, a base disposed on the rail seat, two davit arms, two first winches, and two second winches. The upper deck has a lower pontoon. The upright columns are connected between to the upper deck and the lower pontoon. Each upright column is provided with a support leg that is longitudinally inserted through the upright column, thereby positioning the offshore platform lifting device on the seabed through the upright columns. The two davit arms are disposed the base and drives the base to move laterally through a pushing device. The two second winches each have a second cable passing through the two davit arms. A hook is disposed at a distal end of the second cable.

An apparatus for use in marine platform jacking is disclosed herein. In one aspect, a jetting valve includes a valve body with a piston assembly disposed therein. The piston assembly is selectively operated to open and close the valve. A biasing member is coupled to the piston assembly. The piston assembly includes a first piston and a second piston. The dual pistons, in cooperation with the biasing member, allow the valve to self-seal thereby preventing entry of a fluid which is external to the valve.

The present disclosure generally relates to movable offshore platforms for installing wind turbines, and methods of forming the same. The movable offshore platforms are offshore platforms which were previously used in hydrocarbon production, such as jack-up units. The movable offshore platforms may be decommissioned and retrofitted with equipment for installing wind turbines. The movable offshore platforms may be American-made or otherwise Jones Act compliant. Methods of forming the same are also included.

An offshore platform lifting device for lifting operations at sea after sailed to a certain position of a sea surface includes an upper deck, a plurality of upright columns, a rail seat, a base disposed on the rail seat, two davit arms, two first winches, and two second winches. The upper deck has a lower pontoon. The upright columns are connected between to the upper deck and the lower pontoon. Each upright column is provided with a support leg that is longitudinally inserted through the upright column, thereby positioning the offshore platform lifting device on the seabed through the upright columns. The two davit arms are disposed the base and drives the base to move laterally through a pushing device. The two second winches each have a second cable passing through the two davit arms. A hook is disposed at a distal end of the second cable.

Techniques and devices to assist an offshore unit in going on location and coming off location. A device may include an interface configured to receive a signal indicative of motions of an offshore unit. The device may also include a memory configured to store a set of values corresponding to acceptable motions of the offshore unit, as well as a processor configured to determine if a measured motion of the offshore unit exceeds at least one value of the set of values and generate an indication that going on location by the offshore unit can be undertaken when the processor determines that the measured motion of the offshore unit is less than or equal to the at least one value.

A measurement system that comprises at least one horizontal load measuring unit, that is preferably arranged on the leg guide is provided. The horizontal load measuring device measures or determines horizontal load on the position of the leg where the device is placed, which gives a more accurate indication of the leg bending moment than the rack phase differential measurement. Advantageously, multiple load measuring units can be provided along the leg guide.

A first permissible operating range of the self-elevating vessel is determined based on a first structural analysis of the self-elevating vessel under a first set of conditions. A structural utilization ratio of the self-elevating vessel is determined based on a second structural analysis of the self-elevating vessel under first and second sets of conditions. Safety of lowering the self-elevating vessel from an elevated state to a first hull draft level is determined when the structural utilization ratio is less than a predetermined value. Safety of lowering the self-elevating vessel from the first hull draft level to a second hull draft level is indicated when positional displacement data obtained while the vessel is at the first hull draft level indicates that the positional displacement of the self-elevating vessel while at the first hull draft level is within the first permissible operating range.

A self-installing offshore platform includes a top deck that supports an offshore facility, a column having a top end and a bottom end, the top end connected to the top deck, the column that supports the top deck to maintain the top deck above water in a water body in both the deployed state and the undeployed state of the self-installing offshore platform, a skirt connected to the bottom end of the column, the skirt residing above a floor of the water body in the undeployed state of the self-installing offshore platform and residing on the floor of the water body in the deployed state of the self-installing offshore platform, and a ballastable float positioned between the top deck and the skirt, the ballastable float floating in the water when the self-installing offshore platform transitions from the undeployed state to the deployed state.