A self-propelled offshore installation vessel

Abstract

A self-propelled offshore installation vessel (1) operates at an offshore position and has at least one water pump (27) being operable to pump water from a water inlet opening (22) to a water outlet opening (25) via water conduit pipes (24). The water system can eject water out through the water outlet opening(s), whereby the ejected water interacts with the waves to dampen waves in an affected area (35) of the sea at the self-propelled offshore installation vessel (1).

1 . A self-propelled offshore installation vessel having a hull with an outer side and with a water system, which water system comprises at least one water inlet opening in the hull associated with a controllable inlet valve, water conduit pipes, at least one water outlet opening in the outer side of the hull associated with a controllable outlet valve, and at least one water pump being operable to pump water from the water inlet opening and/or to pump water to the water outlet opening via the water conduit pipes, characterized in that the at least one water outlet opening is provided with a nozzle device and is located at the outer side of the hull at a position of less than 5 meters from the water line at a predetermined draught of the self-propelled offshore installation vessel. 
     
     
         2 . A self-propelled offshore installation vessel according to  claim 1 , wherein the predetermined draught is a draught at which the self-propelled offshore installation vessel is intended to receive a supply vessel, such as a barge with parts to be installed at an offshore installation site. 
     
     
         3 . A self-propelled offshore installation vessel according to  claim 1 , wherein the at least one water outlet opening is a plurality of water outlet openings in the outer side of the hull. 
     
     
         4 . A self-propelled offshore installation vessel according to  claim 3 , wherein at least some of the plurality of water outlet openings are arranged at different heights in the outer side of the hull, preferably arranged with at least one water outlet opening positioned below the water line corresponding to the predetermined draught of the self-propelled offshore installation vessel. 
     
     
         5 . A self-propelled offshore installation vessel according to  claim 4 , wherein several water outlet openings are positioned below said water line. 
     
     
         6 . A self-propelled offshore installation vessel according  claim 1  wherein the hull has a stern end and a cargo main deck and a side section extending upwards at either longitudinal side of the cargo main deck, that the self-propelled offshore installation vessel has ballast tanks and a ballast pumping system for changing the vessel draught between the predetermined draught, at which the cargo main deck is submerged below sea level, and a second draught, at which the cargo main deck is above sea level. 
     
     
         7 . A self-propelled offshore installation vessel according to  claim 1  wherein the at least one water pump is comprised by one or more ballast pumps of the self-propelled offshore installation vessel. 
     
     
         8 . A self-propelled offshore installation vessel according to  claims 1  wherein the at least one water pump has a total water pumping capacity of at least 9000 m 3 /h. 
     
     
         9 . A self-propelled offshore installation vessel according to  claim 1  wherein the at least one water pump is configured as from 2 to 12 water pumps, each having a water pumping capacity in the range of 1000 m 3 /h to 5000 m 3 /h. 
     
     
         10 . A self-propelled offshore installation vessel according to  claims 1  comprising two jack-up legs at a starboard side and two jack-up legs at a port side, one of said two jack-up legs being a forward jack-up leg and the other being an aft jack-up leg, and by the least one water outlet opening being a plurality of water outlet openings which are arranged either at the aft jack-up leg on the starboard side and on the port side, or aft of the aft jack-up leg on the starboard side and on the port side, such as at the starboard side and the port side of the stern of the hull. 
     
     
         11 . A self-propelled offshore installation vessel according to  claim 1  wherein the nozzle device has a cross-sectional area which is smaller than the cross-sectional area of the water conduit pipe connected to the water outlet opening. 
     
     
         12 . A self-propelled offshore installation vessel according to  claim 1  wherein the nozzle device directs the water in a direction different from the direction normal to the outer side of the hull. 
     
     
         13 . A self-propelled offshore installation vessel according to  claim 1  wherein the controllable outlet valve is a spade valve. 
     
     
         14 . A method of operating a self-propelled offshore installation vessel at an offshore position having a sea state with waves, which self-propelled offshore installation vessel has a hull with an outer side and with a water system, which water system comprises at least one water inlet opening in the hull associated with a controllable inlet valve, water conduit pipes, at least one water outlet opening in the outer side of the hull associated with a controllable outlet valve, and at least one water pump being operable to pump water from the water inlet opening and/or to pump water to the water outlet opening via the water conduit pipes, characterized in that the water system is activated to eject water out through the at least one water outlet opening, which has a nozzle device, whereby the ejected water interacts with the waves to dampen waves in an affected area of the sea at the self-propelled offshore installation vessel. 
     
     
         15 . A method of operating according to  claim 14 , wherein the offshore wind farm installation vessel is positioned with its bow facing in direction of the incoming waves, said affected area of the sea being located at least aft of the stern of the hull, and preferably the water system ejects water simultaneously out through water openings on both the starboard side and the port side of the hull.