![Oklahoma Righting 01](https://upload.wikimedia.org/wikipedia/commons/2/26/Oklahoma_Righting_01.jpg)
Parbuckle salvage, or ''parbuckling'', is the righting of a sunken vessel using rotational leverage. A common operation with smaller
watercraft
Any vehicle used in or on water as well as underwater, including boats, ships, hovercraft and submarines, is a watercraft, also known as a water vessel or waterborne vessel. A watercraft usually has a propulsive capability (whether by sail, ...
, parbuckling is also employed to right large vessels. In 1943, the was rotated nearly 180 degrees to upright after being sunk in the
attack on Pearl Harbor
The attack on Pearl HarborAlso known as the Battle of Pearl Harbor was a surprise military strike by the Imperial Japanese Navy Air Service upon the United States against the naval base at Pearl Harbor in Honolulu, Territory of Hawaii, j ...
, and the Italian cruise ship ''
Costa Concordia
''Costa Concordia'' () was a cruise ship operated by Costa Crociere. She was the first of her class, followed by sister ships ''Costa Serena'', ''Costa Pacifica'', ''Costa Favolosa'' and ''Costa Fascinosa'', and ''Carnival Splendor'' built for ...
'' was successfully parbuckled off the west coast of Italy in September 2013, the largest salvage operation of that kind to date.
Mechanical advantage and difficulties
![Parbuckle](https://upload.wikimedia.org/wikipedia/commons/0/04/Parbuckle.png)
While the
mechanical advantage
Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. The device trades off input forces against movement to obtain a desired amplification in the output force. The model for t ...
used by a laborer to parbuckle a cask up an incline is 2:1, parbuckling salvage is not so limited. Each of the 21 winches used to roll the ''Oklahoma'' used cables that passed through two 17-part
tackle assemblies (17:1 advantage). Eight diameter
sheave
A sheave () or pulley wheel is a grooved wheel often used for holding a belt, wire rope, or rope and incorporated into a pulley. The sheave spins on an axle or bearing inside the frame of the pulley. This allows the wire or rope to move fre ...
s, eight diameter sheaves, and one diameter sheave comprised just half the mechanical effort.
A major concern during salvage is preventing rotational
torque
In physics and mechanics, torque is the rotational equivalent of linear force. It is also referred to as the moment of force (also abbreviated to moment). It represents the capability of a force to produce change in the rotational motion of th ...
from becoming a transverse force moving the ship sideways. , lost like the ''Oklahoma'' in the Pearl Harbor attack, was meant to be recovered by a similar rotation after the ''Oklahoma.'' As the ''Utah'' was rotated, however, its hull did not catch on the harbor bottom, and the vessel slid toward
Ford Island
Ford Island ( haw, Poka Ailana) is an islet in the center of Pearl Harbor, Oahu, in the U.S. state of Hawaii. It has been known as Rabbit Island, Marín's Island, and Little Goats Island, and its native Hawaiian name is ''Mokuumeume''. The isl ...
. The ''Utah'' recovery effort was abandoned.
Righting of ''Oklahoma''
''Oklahoma'' weighed about . Twenty-one electric winches were installed on Ford Island, anchored in
concrete
Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...
foundations. They operated in unison. Each winch pulled about by a wire operated through a block system which gave an
advantage of seventeen, for a total pull of 21×20×17, or . In order to increase the leverage, the wire passed over a wooden strut arrangement (a ''
bent'') which stood on the bottom of the ship about high.
Oil had been removed from the ship through the bottom. The ship was lightened by air inside the hull. There was a large amount of weight in the ship which may have been removed prior to righting, but not all could be accessed. About one-third of the ammunition was taken off together with some of the machinery. The blades of the two propellers were also taken off, but more to avoid damage to them than to reduce weight.
Tests were made to check whether restraining forces should be used to prevent sliding toward Ford Island. It was indicated that the soil under the aft part of the ship prevented sliding, whereas the bow section rested in soupy mud which permitted it. To prevent sliding, about 2200 tons of
coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...
soil were deposited near the bow section. During righting, excess soil under the starboard side was washed away by high-pressure jets operated by divers.
The ship rolled as it should have and was right-side up by 16 June 1943, the work having started 8 March 1943. The mean
draft
Draft, The Draft, or Draught may refer to:
Watercraft dimensions
* Draft (hull), the distance from waterline to keel of a vessel
* Draft (sail), degree of curvature in a sail
* Air draft, distance from waterline to the highest point on a vessel ...
of the ship after righting was c. .
Righting of ''Costa Concordia''
![Costa-salvage1](https://upload.wikimedia.org/wikipedia/commons/4/49/Costa-salvage1.png)
Following its
capsizing and sinking in January 2012, the hull of ''Costa Concordia'' lay
starboard
Port and starboard are nautical terms for watercraft and aircraft, referring respectively to the left and right sides of the vessel, when aboard and facing the bow (front).
Vessels with bilateral symmetry have left and right halves which are ...
side to the seaward face of a small outcropping very near the mouth of the harbor of
Giglio, Italy, resting precariously on the incline to deeper water. To right the vessel, four key pieces of apparatus were required:
* a "holdback" system of chains attached to the island on one end and the hull on the other to ensure ''Costa Concordia'' rolled in place;
* a man-made ledge inserted into the island face to provide a landing surface for the vessel;
* a series of
sponson
Sponsons are projections extending from the sides of land vehicles, aircraft or watercraft to provide protection, stability, storage locations, mounting points for weapons or other devices, or equipment housing.
Watercraft
On watercraft, a spon ...
s attached to the hull's
port
A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Ham ...
side so as, when flooded, to increase the torque on the hull and to unburden the
strand jacks;
* an arrangement of cables rising from the edge of the ledge over the sponsons on the port side of the hull.
Tensioning the cables started the roll of the ship. At about the halfway-to-vertical position the sponsons were filled with seawater, and ''Costa Concordia'' completed its roll to upright upon the ledge.
The hull was rotated 65 degrees to become vertical.
Parbuckling was accomplished in three phases:
#Freeing the hull
#Phase of rotation using cables
#Rotation by ballasting with sponsons
At the completion of parbuckling, ''Costa Concordia'' rested on the ledge at a depth of .
[
]
Holdback system
The holdback system consisted of 56 chains in total, of which 22 chains were attached to the port side to go under the hull to the island. Each chain was long and weighed about .[ Each link weighed .
]
Ledge
The ledge was part steel and part grout. There were six steel platforms. The three larger platforms measured each; the three smaller platforms measured each. The 6 platforms were supported by 21 pillars of diameter each and plunged for an average of in the granite sea face of Giglio. The grout filled the space between the land side of the platforms and the sea bed. It totaled 1,180 individual bags with a volume of over and over in weight.[ The grout bags contained an "ecofriendly cement," and were built with eyelets to aid post-recovery cleanup.
]
Sponsons
Eleven steel sponsons were installed on the port side of the hull: two long horizontal sponsons; two long vertical sponsons and seven short vertical sponsons.
*Each long horizontal sponson
**measured ,
**weighed about ,
**provided of buoyancy.
*Each long vertical sponson
**measured ,
**weighed of about ,
**provided about of buoyancy.
*Each short vertical sponson
**measured ,
**weighed about ,
**provided about of buoyancy.
Two steel "blister" tanks were connected together at the hull's bow. They measured in length, in height each, and had a total breadth of about . The whole blister structure (the two blister tanks, the tubular frame and the three anchor pipes) weighed about . They provided a net buoyancy of to the bow section.[
]
Cables
The cable system provided a force of about to start the ''Costa Concordia's'' rotation.[
]
Phase 1 – freeing the hull
The hull of ''Costa Concordia'' rested on two spurs of rock, and was severely deformed from the weight of the ship pressing down on the spurs. This phase began when the strand jacks exerted force and the ship started to return to an upright position. This was "without doubt one of the most delicate phases of the entire recovery plan."[
]
Phase 2 – rotation using cables
This phase began when the hull lifted from the seabed. Rotation continued by tensioning the cables operated by the strand jacks, and continued until the sponson water intakes reached sea level.[
]
Phase 3 – rotation by ballasting with sponsons
The hull continued to rotate, pulled down by the weight of seawater added to the sponsons. The strand jacks and cables went slack. Redundant systems were designed as a guard against failure. For example, two seawater inlet valves were provided to each sponson.[
]
List of parbuckle-salvaged vessels
*
*
*
*
*[
*]
* MS ''Herald of Free Enterprise''
*
*MV '' Janra''
*MV '' Repubblica di Genova''
* MSC ''Napoli'''s separated stern section
*Barge
Barge nowadays generally refers to a flat-bottomed inland waterway vessel which does not have its own means of mechanical propulsion. The first modern barges were pulled by tugs, but nowadays most are pushed by pusher boats, or other vessels ...
''Larvik Rock''
*Fishing trawler
A fishing trawler is a commercial fishing vessel designed to operate Trawling, fishing trawls. Trawling is a method of fishing that involves actively dragging or pulling a trawl through the water behind one or more trawlers. Trawls are fishing ...
''Nieuwpoort 28''
*Fishing vessel
A fishing vessel is a boat or ship used to catch fish in the sea, or on a lake or river. Many different kinds of vessels are used in commercial, artisanal and recreational fishing.
The total number of fishing vessels in the world in 2016 was es ...
'' Sandy Point''
* MS ''Costa Concordia''[
* Jackup work barge ''Sep Orion'']
References
External links
*
Pearl Harbor Raid, 7 December 1941 Salvage of USS ''Oklahoma'', 1942–44
Salvage of the battleship USS ''Oklahoma'' following the attack on Pearl Harbor 1942–46
The Parbuckling Project: ''Concordia'' wreck removal project informative website
*{{YouTube, nVxWhQVUaoI, The salvage of the ''Herald of Free Enterprise'', March 6, 1987
Marine engineering
Marine salvage
Rotation