Abstract:
A berthing facility and method of docking a maritime vessel that features greatly improved stability and is suitable at a wide range of depths. The floating berth is made up of a plurality of buoy components protected by a fendering assembly which constitutes the breasting and mooring dolphins of a conventional fixed berth. The fendering assembly presents shock-absorbing fender panels that help absorb the impact from docking ships, the combined system allowing absorption of large berthing energies with reduced reactions and greater safety. The buoy components are preferably each of a type known commercially as a Satellite Separator Platform (SSP)

Description:
[0001]     This application claims priority to U.S. Provisional Patent application Ser. No. 60/578,669 filed Jun. 10, 2004. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates generally to improved methods and systems for offshore mooring of vessels. In particular aspects, the invention relates to improved methods of configuring a berth and systems for docking maritime vessels at an offshore location. The berth may be used for the following purposes: loading or unloading of cargo; unloading of passengers; refueling or maintenance and repair of maritime vessels. Maritime vessels, in the context used, include naval or commercial ships, barges, tugs, offshore floating platforms and specialty vessels used for the offshore industries.  
         [0004]     2. Description of the Related Art  
         [0005]     An effective berth requires that the floating dock be able to sustain large forces from docking vessel impacts, winds, waves, and currents against the maritime vessel while it is at berth. The berthing arrangement must also permit the safe transfer of cargo, passenger crew, and components for maintenance or provisions from the maritime vessel to the floating dock. Additionally, a tanker captain or harbor pilot must be comfortable or somewhat familiar with the berthing facility in order to safely maneuver the ship and prevent novel and unfamiliar docking procedures to be used. The berthing facility should be economical, thereby allowing its construction and installation without undue expense that might otherwise eliminate or limit its practical use.  
         [0006]     Although floating docks are commonly used for docking of pleasure craft in yacht marinas, such an arrangement would not be suitable for use in deep water or for use with the offloading and loading of dangerous cargos in deeper areas farther from shore and from the general populace. The offshore application of a floating berth must account for required durability and safety.  
         [0007]     Known berthing arrangements for maritime vessels at sea are not optimal and include inherent risks during transfer of hazardous cargo. U.S. Pat. No. 6,546,739 issued to Frimm et al., for example, teaches a floating platform, such as a modified very large crude carrier (VLCC) that is tethered to a turret system or a CALM buoy, that is moored in place. The tether connection is a single-point mooring that allows for “weathervaning,” or movement of the tanker about that mooring point during current, waves or wind changes. Such movement of the tanker during offloading or during sensitive cargo transfer to another vessel is problematic because the relationship between the tankers can change quickly and such an arrangement may become substantially unstable in poor weather or sea conditions.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention provides an improved berthing facility and method of docking a maritime vessel. The invention features greatly improved stability and is suitable at a wide range of depths. In an exemplary embodiment, the floating berth is made up of a plurality of buoy components that are arranged in a linear fashion and protected by a fendering assembly which constitutes the breasting dolphins of a conventional fixed berth. The fendering assembly presents shock-absorbing fender panels that help absorb the impact from docking ships. The buoy components are preferably each of a type known commercially as a Satellite Separator Platform (SSP) include a center column assembly, the position of which may be altered as needed for movement of the SSP or for stationary placement. The floating berth is moored in place to the sea floor and, preferably, is provided with bow and stern buoys, for added anchorage and stability, which constitute the mooring dolphins of a conventional fixed berth. The general configuration, which constitutes a floating berth, is a central embodiment of the invention. The fendering system provided on the berth, which is an embodiment of the present invention, provides a degree of adjustment to improve fendering efficiency over a wide range of hull shapes thereby reducing local ship side panel loads and improving safety against ship damage. A related aspect of the present invention is the use of deep set fendering which tends to cause the primary reactions to occur closer to the ship keel thereby preventing overturning moments on the floating berth components.  
         [0009]     In practice, a ship, tanker, or other maritime vessel, is docked in a stable parallel relation to the floating berth, which facilitates safe conduct of a cargo, personnel or equipment transfer, or maintenance procedures. The lowered center column assemblies of the SSP&#39;s within the docking platform provide exceptional stability for the floating platform and allow means of gangways and personnel access between the individual buoys which are a further aspect of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     For further understanding of the nature and objects of the present invention, reference should be made to the following drawings in which like parts are given like reference numerals and wherein:  
         [0011]      FIG. 1  is a plan view depicting a tanker that is docked at an exemplary floating berth constructed in accordance with the present invention.  
         [0012]      FIG. 2  is an end view of the berth arrangement shown in  FIG. 1 .  
         [0013]      FIG. 3  is a free body diagram depicting reactions of the maritime vessel and an individual breasting buoy during docking.  
         [0014]      FIG. 4  is a plan view of a typical mooring pattern for a single buoy used within the docking arrangement shown in  FIGS. 1-3 .  
         [0015]      FIG. 5  is an illustration of physical forces involved in the exemplary breasting buoy arrangement shown in  FIGS. 1-4 .  
         [0016]      FIG. 6  depicts an exemplary floating berth constructed in accordance with the present invention as configured when emplaced at a location in the sea. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]      FIGS. 1-6  depict an exemplary floating berth and mooring arrangement, generally indicated at  10 , which incorporates a longitudinal floating berth or docking facility  12 . The floating berth  12  is located in an area of ocean  14  that is remote from shore. The floating berth  12  is made up of a plurality of buoy components  16  that support a protective fendering arrangement  18 . These buoys  16  are used as breasting and mooring dolphins which react against the side of a ship to hold it in position. While there are four buoy components  16 , shown in  FIGS. 1 and 2 , those of skill in the art will understand that there may be more or fewer breasting and mooring buoys, as necessary or desired for stability of the maritime vessel. The linear arrangement of the buoy components  16  as well as desired spacing may be maintained by a suitable system of lashings, struts and the like (not shown) but exemplified by the outline  18  on  FIG. 1 . The docking platform  12  is preferably provided with suitable upper walkways  17  (see  FIGS. 1 and 6 ), as well as stanchions and lines (such as lines  32 ) necessary for securing of a maritime vessel thereto. The docking platform  12  may be provided with loading equipment for the handling and processing of liquids, gases and solids or for other cargo that might be transported by a tanker or vessel. At the ends of the breasting buoys, other buoys  27  and  28  may be provided for attaching ship bow and stern lines. These buoys  27 ,  28  then function as mooring dolphins.  
         [0018]     The buoy components  16 ,  27  and  28  are preferably Satellite Separator Platform (SSP) floating vessels of the type described in U.S. patent application Ser. No. 09/980,944 filed Oct. 22, 2001, which is owned by the assignee of the present application. That patent application is incorporated herein by reference. The SSP vessel is also marketed commercially by OPE, Inc. and its affiliated companies located in Houston, Tex. Basically, the SSP vessel includes a floating hull portion  20  with a center column assembly  22  that may be extended or retracted vertically downwardly into the sea  14  to provide improved stability while floating. An SSP vessel is generally suitable for water depth applications from approximately 100 feet to approximately 10,000 feet. The center column assembly  22  may be used to store ballast or other materials including fire fighting chemicals or hazardous chemicals to protect them from any marine vessel impact by the security of the outer hull structure.  
         [0019]     The fendering arrangement  18  is a system of bumpers and/or shock-absorbing panels that surround the breasting buoys  16 . The fendering arrangement  18  also serves to present the buoys  16  in a substantially linear arrangement as a flat-faced dock.  FIG. 2  depicts an end view of a fender  18  on a breasting buoy  16  and indicates the means to alter the angle of the fender  18  by the fender adjustments  19 . As can be seen in  FIG. 2 , the fender  18  is deep set below the surface of the water  14  so that lower portions of the hull of the tanker  30  may be engaged by the fender  18  during docking. The fender adjustments  19  may be threaded adjustment bolts or other devices known in the art capable of adjusting the angle of the fender  18  with respect to the adjacent buoy  16 . By providing such adjustments at added portions of the fender  18 , the orientation of the fender  18  can be made to match the hull of a docking tanker or other maritime vessel  30 . Each of the buoys  16  is moored to the ocean floor  24 , as depicted in  FIG. 2 , by mooring lines  26 . There is a bow buoy  27  and a stern buoy  28  located at either end of the dock  12 , as shown in  FIG. 1 . The bow and stern buoys  27 ,  28  are each moored to the ocean floor  24  in the same manner as the buoy components  16  of the dock  12 . Their presence adds stability and anchorage for the berthing arrangement  10  and tanker or other maritime vessel  30 .  
         [0020]     Several docking lines  32  secure the tanker or other vessel  30  to the floating berth  12 . The tanker  30  is disposed in a substantially parallel relation to the dock  12 . This parallel docking arrangement eliminates weathervaning of the tanker  30  with respect to the docking platform  12  thereby vastly improving safety for a wide range of offshore activities. Two additional docking lines  34 ,  36  are used to secure the bow and stern of the tanker  30  to the bow buoy  27  and to the stern buoy  28 , respectively.  
         [0021]      FIG. 3  is a free body diagram illustrating how the deep set fendering arrangement  18  provides a reaction closer to the keel of the vessel  30 . As shown, the horizontal reaction of the fendering (illustrated as arrow  41 ) is above that of the mooring reaction (illustrated by arrow  40 ). This aspect tends to cause the dock fendering  18  to match the face of the vessel  30  and improve motions. It also prevents the vessel  30  from overrunning the dock  12 . The dock fendering being provided with fender adjustments  19 ,  FIG. 2 , maintains vertical buoy orientation under severe loading while improving the matching of well faired maritime vessel hull forms, such as LNG carriers, thereby reducing hull damage of vessels with volatile cargo. This feature increases safety for the vessel  30  and floating berth  12 .  
         [0022]      FIG. 4  is a plan view of a single buoy component  16  illustrating an exemplary anchoring arrangement of the buoy  16  to the sea floor  24 . As shown, there are multiple mooring lines  26  that provide load-sharing and redundancy. By mooring the individual buoy components  16  of the dock platform  12  to the seabed, the dock platform  12  is capable of absorbing significant energy from the impact of vessels, such as vessel  30 , while minimizing the forces that are imparted to the side shell of the docking vessels. The energy absorption is created by the compliant system, which is created by the effective linkage of the mooring lines  26  and the reserve buoyancy of the buoy components  16 .  FIG. 5  depicts this energy absorbing effect in a free body diagram of a simple linkage mechanism. The horizontal reaction is equal to the horizontal force to arrest the lateral motion or static forces acting on the vessel  30 . The reaction to the maritime vessel  30  is equal to the buoyancy divided by the trigonometric tangent function of the angle “A” shown in  FIG. 5 . The energy is the calculus integral of the horizontal force taken with respect to the horizontal distance which is related to angle “A.” The physical result is that the energy absorption is a result of the buoyancy offered by the breasting buoys and the angle of the reacting mooring lines. The energy absorption is increased by the amount of buoyancy implemented, therefore allowing increased lateral motion of the buoy, minimizing the horizontal reaction during impact. By utilizing buoyancy to absorb the maritime vessel reactions, the docking arrangement  10  helps to avoid damage to the vessel  30  that might otherwise result from severe winds, currents, pilot or attendant tug boat error. By providing a safe mooring away from shore and populated areas capable of many times the energy absorption of conventional breasting and mooring berths, the floating dock increases safety during loading and offloading operations of many hazardous materials and minimizes congestions and delays in busy harbors. Overly busy and congested harbors lead to difficult increases in controls for homeland security.  
         [0023]     The docking platform  12 , shown in  FIG. 6 , may be moved about by towing or by other means of propulsion.  FIG. 6  depicts the docking platform  12  in a stationary position within the sea  14  wherein it may be moored in place by mooring lines  26 . It is noted that the center column assemblies  22  of the buoy components  16  are extended into a lowered position, so that they extend well below the hull  20  of the buoy  16 . The lower portions of the center column assemblies  22  typically include weighted ballast (not shown). This adds significant stability to the platform  12  against wave forces that would create heave, pitch, roll or yaw motions by the platform. This feature allows for the use of walkways  17  between the buoys  16  that could be safely traveled during normal sea conditions. The use of interconnecting walkways  17  for the berthing system is a further aspect of the invention.  
         [0024]     Propulsion systems (not shown) may be incorporated into the docking platform  12  to augment or replace the system of mooring lines  26 . Supplementary thrusters with an appropriate dynamic control system may be used to minimize lateral motion or maintain station during maintenance of the docking platform  12 . During transport or movement of the berth  12 , the center column assemblies  22  may be raised vertically with respect to the floating hull  20  so that there is minimal drag on the berth  12  or when it is necessary to enter shallow water as a port.  
         [0025]     As a fully contained vessel/platform, the docking platform  12  can be fabricated in virtually any construction port in the world and fully equipped prior to being towed to its installation site and, thereafter, anchored in place. It is further apparent that the floating berth principles, especially when coupled with self-propelled mobility, offer a mobile port or offshore command center which, when coupled with larger versions of the SSP or similar components, yield a series of storm stable systems for a variety of both domestic and foreign applications.  
         [0026]     Those of skill in the art will recognize that numerous changes and modifications may be made to the exemplary systems and methods described herein without departing from the scope and spirit of the invention. In fact, the invention is intended to be limited only to the claims which follow and all permissible equivalents thereof.