Expert Witness

Marine Accident Investigation

Tension Technology International (TTI) staff have extensive experience with investigating the causes of accidents in marine mooring and cargo systems. The accident investigation is important to establish responsibility as well as to prevent a recurrence. We can thoroughly evaluate the suitability of mooring and towing ropes, steel wire and chain, cargo hoses, and other factors as part of insurance and legal investigations and also to help prevent future accidents.

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TTI engineers have participated in almost a thousand break tests of fiber ropes and have analyzed many rope failures. We have a broad range of experiences in fiber rope design, application and laboratory analysis. In addition, we have unique tools for and experience with mooring and towing system analyses.

TTI has investigated three major towing accidents. One involved the use of two tugs towing a platform. We examined and tested the failed towline and performed computer analyses to predict probable loading histories during the tow. Our investigation enabled the client to establish a strong defense and settle for much reduced damages. In another case, we examined the towline and conducted yarn testing. Based on our testimony, the court ruled that the towline was inadequate.

TTI has investigated in excess of thirty single point mooring (SPM) hawser system accidents. We advised the U.S. Navy to use a more durable fiber rope material, which alleviated a pattern of breakouts at fleet moorings. In another case, we determined that improper splicing methods were causing accelerated rope fatigue and recommended changes which alleviated the problem. In an SPM accident case, we arranged for and analyzed computer analyses and model tests which demonstrated that mooring loads probably exceeded the strength of the failed component. We also reviewed and critiqued the SPM designer's calculations and design methods.

TTI has also investigated several pierside mooring breakouts. In one case, all 16 mooring lines on a cargo vessel parted. TTI's OPTIMOOR program was used to evaluate environmental loads on the vessel and to show that the mooring would have been safe if the mooring lines were in adequate condition. Examination and analysis of the mooring lines provided an objective assessment that their break strength was greatly deteriorated at the time of the accident. In another case, a tanker was pulled off a pier by a passing ship, causing a hose failure. OPTIMOOR was again used to evaluate the mooring arrangement. It was shown that several mooring points shown in the port information booklet did not actually exist, and their presence would have permitted an adequate mooring for the circumstances.

TTI has investigated many oil cargo hose failures. We have participated in over a hundred burst testing of new and used hoses of various designs and services and have examined many failed hoses. From these experiences we can usually identify the causes of hose failure. We can inspect and dissect failed hoses to identify failures caused by hose design and manufacturing defects and by age, in-service damage, and poor handling.

Three hose accident investigations involved spillage of hot asphalt or heavy fuel oil. In one case, we determined that the terminal's hose was not of the proper design and that the terminal had inadequate mooring facilities. The terminal then dropped its case against the barge operator. In another case, we determined that the hose manufacturer did not practice adequate production, quality control, and testing practices. In a third case, we determined that the hose manufacturer had recently changed to an inferior rubber compound for the critical inner liner of the hose, which then cracked at cold temperatures and caused the development of a massive hose failure under pressure. In both these later cases, the hose manufacturer took responsibility for the accident. Other hose investigations have involved large floating and underwater hoses used at SPMs and sea berths.

TTI has investigated many personnel injuries, including cases involving dock and marine personnel. In a case in which a line was thought to be too weak, we established that instead the dock personnel were using too many turns on the capstan and had attempted to free a snagged line with the capstan. We then recommended proper training procedures to prevent recurrence. TTI staff have also been involved in personnel injury investigations concerning umbilicals, lifting slings and webbing, oil booms, derrick slewing ropes, forestry ropes, and even `tug-of-war' ropes.

TTI has the wide breadth of experience to handle most aspects of a marine mooring or cargo system accident or failure investigation. Instead of just focusing on one element of a case, for example a hose failure, we can also assess if the mooring lines were of the proper type and in good condition and if the mooring arrangement was properly made and tended. We have the expertise to conduct detailed failure investigation and the experience to provide accurate and reliable testimony in virtually any case involving the use or failure of flexible tension components and systems.

TTI has investigated failures of steel wire ropes used for mooring gas carriers and chains in offshore spread moorings.