Experience shows that in such circumstances the speed and effectiveness of the initial response measures invariably decide the final outcome of the operation.

Emergency Containment, Past and Present
In the distant past, sailing vessels carried almost unlimited stocks of canvas which would contain any damage to their wooden hulls (generally caused by collision or grounding). It was a simple matter for the carpenter to secure the canvass to the wooden planking. Later hulls were made of steel and engines replaced sails, and this relatively simple means of damage control was no longer available. The causes of damage became more varied and included internal explosion and cargo-related incidents, as well as increased risk of fire, grounding, and collision. In warships there was also risk of serious battle damage caused by missiles, shells, bullets, and shrapnel to be considered.

Current speedy on-site response options include the use of primitive collision mats, as well as a large range of even less sophisticated tools such as concrete boxes, wooden plugs, plywood, tarpaulins, and mattresses. For mores serious damage, heavy underwater plate repair involves using the unwieldy Cox underwater gun and specialized underwater welding. Most importantly, much time is lost in the manufacture, provision, and installation of a such a conventional temporary welding patch.

Even with all this experience, there is no single generally accepted method for sealing off damaged hull areas. The reason is presumably that no two damage cases are alike - indents, material, internal cargo, location, and weather conditions always differ from case to case.

Additionally, since the cost of having an immediately available underwater damage sealing system on board is seen as a shared responsibility between ship-owner/operator, insurance, maritime authorities, and the salvage industry, there is no standard arrangement for the provision of any first-aid response.

In an effort to offer a simple and cost-efficient solution, Norway's Miko Marine has introduced Magnetic Plasters. The patented technology represents a new approach to the fundamental principle of salvage to keep the water out and the oil in a damaged vessel.

Developing Magnetic Plasters
Two specific incidents led to the concept of this new system. In 1995, when the ex-Russian cruiser, Murmansk, was being towed to India for break-up and scrap, the tow parted and the vessel stranded off Northern Norway. A reputable Norwegian salvage company was awarded the contract to refloat the vessel, but failed to restore buoyancy. The company had difficulties welding replacement plating to the hull due to a mixture of fragile and variable thickness plating. The vessel remains sunk in position, where it presents no serious navigational or environmental threat.

Around the same time, a sister company of Miko Marine purchased a North Sea offshore loading buoy for scrap. Having extracted 4,000 tons of internal iron ore for alternate use as ballast on a crane vessel, the crew tried to close the opening prior to towing the buoy across the Bay of Biscay to Spain for final disposal. The task of full penetration welding the 40mm plate to ensure water tightness proved disproportionately complex and expensive.

These incidents illustrated the need for more simple means of providing temporary or semi-permanent watertight integrity. Subsequent analysis by Miko Marine identified the possibility that some form of easily applied, flexible magnetic patch or plaster might provide the necessary barrier.

Such a plaster, taking into account current developments in metal magnetization and nylon fiber manufacture, would provide a product of high mechanical strength combined with strong adhesive capability, while retaining flexibility in deployment, storage, and application. Goals for the plaster's development included low cost and minimum storage space requirements, making it an attractive onboard response tool. Most important to the design team was that no hot work be involved in its application.

The Miko development team achieved its goals, and the new plaster repair system is easier, quicker and cheaper and far less demanding on heavy equipment and support facilities than current techniques. It can be rapidly deployed by air to any maritime incident site, and has also found application in ports, harbors, oil rigs, etc. Of course, such a system does not replace current and long-proven techniques, but evidence suggests that it complements them, and should be considered as an option at the incident planning stage.

In technical terms, the individual features of strong magnetism in a rubber matting combined with recent fiber technology can produce predictable behavior in an underwater sealant. The patented heavy duty magnetic tarpaulin is called Miko Plaster. It is ideal for routine operations requiring a temporary watertight seal over hull openings, as well as emergency response damage resulting from collision and grounding.

Formally certified by Det Norske Veritas, Miko has supplied plasters to more than 200 different customers for applications, including routine afloat survey and repair (alternative to dry-docking), emergency marine salvage and wreck removal following collision and grounding incidents, and oil spill pollution limitation. Miko Plaster is also provided for closing sea chests on a storage tanker in the Norwegian sector of the North Sea using ROVs, in circumstances where diving operations are not permitted.

The Miko plaster adapts to the local geometry of the damaged area and the Kevlar/Aramide reinforcement provides strength and protection against puncture. Uneven steel plates, fractures and indents normally following a grounding are accommodated by using a special Hat Shaped Miko Plaster. This is a strong tarpaulin made of fabrics chosen for their high resistance to most chemicals and great mechanical strength. The main component has a high degree of stretch and shear strength. Aramide fiber matting - similar to that used in bullet proof vests - is used for further reinforcement and protection from puncturing. The patches are secured with rubber sealing and an aluminium frame that is stapled around the edge. When moving any damaged vessel in bad weather or a strong tideway, patches can be further secured with especially powerful magnets.

When fuel oil tanks are damaged following a vessel grounding, an immediate spill often occurs. The tank may still be half-filled with oil and authorities require a temporary sealing of the damaged tank before any off-loading or transfer to repair yard is permitted.

A damaged underwater hull is characterised by its protrusions, sharp edges, indents, and often oily surface. This underwater damaged area can present special problems. Large indents and protrusions in all directions makes a flat patch or tarpaulin unsuitable, so Miko developed the Hat Shape plaster. It follows the curvature and is supported by the remaining structure of the largest possible area when differential pressure is achieved. The patch is protected against sharp edges by the Kevlar/Aramide reinforcement, which can be altered in thickness and strength by varying the number of layers. The patch is temporarily secured using magnets and finally forced to the hull with a special tool called the HD 200. Its dimensions are one-tenth of the well-known Cox gun, but it penetrates the same steel thickness. It can be reloaded underwater and is very efficient. The diver brings with him preloaded barrels and simply pushes the barrel into the tool and fires the gun.

Examples from the Field
The Highland Faith went aground outside New York on December 22, 2000, causing an 82-foot tear and significant indent in the hull. Two cargo holds and the fuel oil tank, carrying 500 tons of heavy fuel oil, were damaged. The vessel was loaded with more than 70,000 tons of gasoline. The US Coast Guard would not allow the ship to move or off-load its cargo before the damaged area was patched. The vessel was anchored at the Gatwick oil terminal and other vessels were lining up to offload their cargo, so a quick response was very important.

One possible solution was to install a cofferdam, which would have required crane vessels, long preparation time, and high costs. The client instead chose Miko's Hat Shaped Plaster. Under difficult conditions, with snow, wind, freezing temperatures, and current exceeding three knots, the installation was completed within a couple of days. The vessel was allowed to offload its cargo and sail to a repair yard for permanent repair.

Miko's first repair came during December 1998, when the Russian vessel Piotr Vililij grounded in Norway. It was not allowed to continue its voyage before the heavy fuel oil inside the damaged tanks was secured. Miko patched the ship, and the next morning she was allowed to go to dry-dock for permanent repair In May 1999, the Asphalt Navigator grounded outside the Dominican Republic. More than 60 square meters of Miko Plaster was installed, allowing the vessel to cross the Atlantic and dry-dock in Piraeus, Greece.

On a side note, the work was approved by a warranty surveyor, but our main concern was how to get our supervisor back home after having successfully completed the job. He was so popular that instead of payment we had to pay ransom money to get him safely back home. Miko Marine does not claim to provide "magic patches" for all vessel openings, but the company has gained valuable experience in these specialized repairs over the years. Perhaps most importantly, the company is and aware of the limitations of their products and solutions, which enables them to effectively complement traditional salvage techniques. UW
Nicolai Michelsen is the Managing Director for Miko Marine AS. The patented Miko Plaster technology is represented in the United States by Jack Vilas and Associates of Morgan City, Louisiana (800-255-4643).