U.S. Navy Ship Salvage Manual Volume 6 - Oil Spill Response

S0300-A6-MAN-060Ships and craft, such as offshore supply vessels, tugs or barges, may be provided by a number ofsources, depending on the location of the spill and the nature of the response. Ships and offshorevessels provide convenient mobile command sites; some types of ships are suitable for use asworking platforms, for towing boom/skimmer systems or for providing berthing, messing, medicalor industrial shop support. Some ship types that are particularly useful during spill responseoperations include:• Offshore supply vessels (OSV). The relatively small size and maneuverability of thesevessels, coupled with a large, low-freeboard working deck and towing capacity, makesthese vessels ideal platforms for skimmer support, dracone towing, spill monitoring,personnel and equipment transport and chemical deployment. Many OSVs areequipped with mud tanks and can be used for transporting waste oil. OSVs can be usedas mobile command sites, although the smaller vessels may have very limited communicationsfacilities. Most OSVs have berthing for only the normal crew of about five,although vessels designed for anchor-handling or salvage work usually have berthingfor an additional 15 to 20 persons. Some OSVs, particularly those set up for salvagework are equipped with light cranes. Except for those equipped with controllable-pitchpropellers, most OSVs cannot maintain the one- to two-knot tow speeds required forskimmer operations. The utility of OSVs can be expanded by embarking berthing,communications, work or equipment vans or liquid cargo containers for transportingwaste oil.• Fishing vessels. Fishing vessels vary in size and capability. Most have clear workingdecks aft or amidships and deck winches or capstans. Many have derricks or A-framesthat can be used to lift skimmers, boats or oil boom. Most fishing vessels are suitablefor towing or deploying boom and for offshore work in rough weather. Boom deploymentoperations are very similar to some fishing operations and are readily grasped byfishing crews. Fishing vessels of appropriate size can perform most of the tasks listedfor OSVs.• Tankers and tank barges. Tank vessels may be required to lighter a stricken tanker thatis the source of the spill or to receive waste oil from skimmers or dracones.• Other barges. Hopper barges are good receptacles for oily debris. Flat-decked bargescan be moored at convenient locations as floating piers and work platforms to supportskimmer and small boat operations.• Dredges. Large liquid storage capacity combined with pumping systems designed tomove viscous materials make hopper dredges ideal receiving platforms for heavy orweathered oil. Some dredges are able to skim oil. A Soviet dredge employed on theEXXON VALDEZ spill was designed as a trailing hopper dredge with oil recovery capability;several U.S. Army Corps of Engineers dredges were also used in the EXXONVALDEZ spill without modification.• Tugs. Harbor tugs can deploy boom, tow boom, skimmers and dracones, transport personneland equipment, support small boat and skimmer operations, tow disabled3-24