Technical Issues: Salvage in Presence of Hazardous Cargo, Underwater Salvage, Refloating

A chemical barge, fully laden with a hazardous polluting substance and inbound to San Juan, Puerto Rico, breaks away from its tow off Isla de Cabras. The barge is double-bottomed, 300 feet long by 43.5 feet, with a depth of 18 feet. It contains 30,000 barrels of cargo in a 5-by-2 tank arrangement. The bottom is hard and the wind is onshore. The situation unfolds at two levels of complexity.


The barge grounds on a 12-foot pinnacle. The integral cargo tanks are intact. The grounding force is approximately 800 tons; however, the barge cannot be pulled off due to the danger of tearing open the remainder of the bottom. The barge is equipped with pumps, but the generator that drives them is disabled.


The barge is dragged over the pinnacle, is torn extensively, and sinks in 50 feet of water. The nature of the cargo is such that it must be removed and promptly. There is no leakage of cargo, but all double-bottom tanks and the after-rake compartment are breached. The wing tanks are intact. The barge is upright on a relatively flat, hard bottom with cargo vent valves closed. The underwater visibility is 10 to 20 feet, and all cargo pumping systems, piping, and valves are sound and in operating condition. The pump room is accessible to divers.


Technical Issues: Rescue Towing, Refloating, Jettisoning

En route from North Africa to a deepwater port in the Gulf of Mexico, a fully laden 250,000-DWT Very Large Crude Carrier (VLCC) loses power off Sombrero Key in the Florida Straits. She is carrying a full cargo of North African crude oil (44 º API). The foreign-flag VLCC is owned by a major U.S. oil company. The situation unfolds at two levels of complexity.

Mechanical Breakdown

The VLCC drifts toward shore. If she does not obtain a rescue tow, she ultimately will strand at Delta Shoal. The ship is in a head current of 1.5 to 3 knots, with a 25-knot south-southeast wind. Delta Shoal is 34 miles northeast of the ship when the ship loses power; the overall drift period to Delta Shoal, given the current and wind conditions, is 19 hours.


A tug fails to arrive in time, and the ship drifts and strands, with light pollution. The grounding force is 27,000 tons.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement