Fender assembly and method for locating a substructure or barge in a moonpool of a ballastable transporter

Abstract

The invention relates to a fender assembly which forms part of a floatable ballastable transporter ( 1 ) comprising pontoons ( 6 ) which define a moonpool ( 4 ) for the location of an offshore platform substructure ( 3 ) or a barge, and a load transfer construction ( 7, 10, 12, 13, 14, 25, 26, 27, 28 ) above the pontoons ( 6 ). The fender assembly comprises fender support structures ( 16 ) on opposite sides of the moonpool ( 4 ), the fender support structures ( 16 ) having sliding supports ( 17 ) sloping towards the moonpool ( 4 ), and fender members ( 20 ) which are slidingly supported by the sliding supports ( 17 ). The invention also relates to a method for locating and centring a substructure ( 3 ) or barge in a moonpool ( 4 ) by using a fender assembly according to the invention.

1 . A fender assembly which forms part of a floatable ballastable transporter ( 1 ), the ballastable transporter ( 1 ) comprising: 
 pontoons ( 6 ) which define a moonpool ( 4 ) for the location of a substructure ( 3 ) or a barge;    a topsides load transfer construction ( 7 ,  10 ,  12 ,  13 ,  14 ,  25 ,  26 ,  27 ,  28 ) above the pontoons ( 6 ), for transferring load from a topsides ( 2 ) above the moonpool ( 4 ) to the transporter ( 1 );    structural elements ( 8 ,  9 ) interconnecting the pontoons ( 6 ) and the topsides load transfer construction ( 7 ,  28 );    the topsides ( 2 ) can be lowered onto or lifted up from a substructure ( 3 ) or barge located in the moonpool ( 4 ) by lowering or raising the transporter ( 1 ) by ballasting or deballasting;    the fender assembly dampen relative movements in the sway direction (y) between the transporter ( 1 ) and the substructure ( 3 ) or barge, the fender assembly is characterized by 
 fender support structures ( 16 ) secured to the topsides load transfer construction ( 28 ) on opposite sides of the moonpool ( 4 ), the fender support structures ( 16 ) having sliding supports ( 17 ) sloping towards the moonpool ( 4 ), fender members ( 20 ) which are slidingly supported by the sliding supports ( 17 ) and are movable along the sliding supports ( 17 ) between an upper position ( 20 ′) and a lower position ( 20 ), and  
 fender elevators ( 21 ) arranged to selectively pull the fender members ( 20 ) up the sliding supports ( 17 ) or letting the fender members ( 20 ) slide down the sliding supports ( 17 ) by the force of gravity (g).  
   
     
     
         2 . A fender assembly according to  claim 1 , wherein the fender elevators comprise winches ( 21 ) secured to the topsides load transfer construction ( 28 ) and cables ( 22 ) extending from the winches ( 21 ) to the fender members ( 20 ).  
     
     
         3 . A fender assembly according to  claim 1  or  2 , wherein the fender members ( 20 ) are adapted to carry ballast.  
     
     
         4 . A fender assembly according to any of the preceding claims, wherein the fender members ( 20 ) have ballast compartments ( 23 ) for ballast water.  
     
     
         5 . A fender assembly according to any of the preceding claims, wherein the fender members ( 20 ) are elongated and extend along the sides of the moonpool ( 4 ).  
     
     
         6 . A fender assembly according to any of the preceding claims, wherein fender boards ( 24 ) are arranged on the side of the fender members ( 20 ) facing the substructure ( 3 ) or barge.  
     
     
         7 . A method for locating and centring a substructure ( 3 ) or barge in a moonpool ( 4 ) of a ballastable transporter ( 1 ) as defined in the preamble of  claim 1 , using a fender assembly according to any of the claims  2 - 7 , the distance (b) between the fender members on opposite sides of the moonpool in their lower position ( 20 ) being essentially equal to the width (w) of the substructure ( 3 ) or barge, characterized by: 
 a) pulling fender members ( 20 ) on opposite sides of the moonpool ( 4 ) up the sliding supports ( 17 ) by activating the fender elevators ( 21 ), to provide adequate clearance for entering the substructure ( 3 ) or barge in the moonpool,    b) entering the substructure ( 3 ) or barge in the moonpool ( 4 ) by a relative movement between the transporter ( 1 ) and the substructure ( 3 ) or barge in the surge direction (x),    c) letting the fender members ( 20 ) slide down the sliding supports ( 17 ) by the force of gravity (g) by deactivating or releasing the fender elevators ( 21 ), thereby reducing or eliminating the clearance between the fender members and the substructure ( 3 ) or barge, whereupon    a relative movement between the transporter and the substructure ( 3 ) or barge in the sway direction (y) pushes a fender member ( 20 ) up a sliding support ( 17 ) and produces a centring force (L) between the fender member ( 20 ) and substructure ( 3 ) or barge.    
     
     
         8 . A method according to  claim 7 , using a fender assembly according to any of the claims  3 - 6 , wherein the fender members ( 20 ) are ballasted to a predetermined weight.  
     
     
         9 . A combination of a fender assembly according to any of the claims  1 - 6  and a substructure ( 3 ) or barge, characterized by the distance (b) between fender members on opposite sides of the moonpool in their lower position ( 20 ) being essentially equal to the width (w) of the substructure ( 3 ) or barge.  
     
     
         10 . A combination of a fender assembly and a substructure ( 3 ) or barge according to claim  10 , wherein the distance (b) between the fender members on opposite sides of the moonpool in their lower position ( 20 ) is slightly larger than the width (w) of the substructure ( 3 ) or barge.