Options for Improving the Safety of DUKW Type Amphibious Vessels (2021)

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1 Executive Summary Safety on DUWKs—amphibious vessels first produced during World War II and long used for sightseeing tours—has been an area of special concern for the United States Coast Guard (USCG) and the National Transportation Safety Board (NTSB).1 A mass fatality sinking in 1999 led to significant changes in how USCG oversees the DUKWs under its jurisdiction. When another DUKW sank, costing 17 lives, while on a tour in 2018, both government and the tour industry revisited their previous responses and recommendations and looked anew for solutions. The USCG Assistant Commandant for Prevention Policy (CG-5P), Office of Design and Engineering Standards (CG-ENG) asked the National Academies of Sciences, Engineering, and Medicine (the National Academies) to provide guidance to USCG on actions that will increase safety on DUKWs used for commercial passenger service. USCG specifically requested inves- tigation of changes to vessel design, engineering, and outfitting and also encouraged the exploration of operational and enforcement changes. DUKWs are essentially military cargo trucks that float. Although tour operations that use the historic vessels from World War II have adapted the DUKWs to meet modern safety standards to the extent possible, some hazards of the original design remain. Modified DUKWs, such as Stretch 1 An independent agency, NTSB investigates accidents—often in conjunction with other agencies—but will independently analyze any collected evidence. NTSB will then release an accident report that determines probable cause and issues safety recommendations. While the NTSB recommendations are not mandatory, within 90 days, the designated party (in this case USCG) must respond in writing as to why it agrees or does not agree to the recommendations.

2 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS DUKWs from the 1990s, and Truck Ducks, purpose built in the early 2000s for sightseeing tours, have remedied some of these remaining hazards, but not all. Moreover, because of the many adaptations over time, individual vessels within the DUKW fleet exhibit a significant amount of variability. DUKWs are at greater risk of sinking—and sinking more quickly—than modern small passenger vessels. They sit low in the water and can be easily swamped by waves. In addition, the requirements for operating on land meant that the historic vessels had numerous locations where water could enter the hull. Maintenance procedures and operating restrictions have long been used to compensate for the vessel’s design shortcomings. NTSB and USCG have identified the presence of canopies as a contrib- uting factor to the loss of life during DUKW fatality events. Tour operators use canopies and, in some cases, clear plastic side curtains, to provide cus- tomer comfort during tours. However, if the vessel sinks, these enclosures can prevent passengers from escaping. After the 2018 casualty event, NTSB and USCG both recommended that tour operators remove canopies. The report examines actions that will improve survivability for the vessel and for persons on board. The report reviews design, engineering, and outfitting options to provide reserve buoyancy and prevent flooding, and it assesses the potential for additional restrictions on operating areas to provide a safer environment for waterborne tours. It also evaluates the advisability of wearing life jackets while on the water and covers methods for improving safety operations. Recognizing that DUKW tour operators have improved canopy designs since the 1999 sinking, the report reviews the designs for canopies and side curtains currently in use. Still, improvements are needed. Canopies should be considered “restrictive canopies” unless demonstrated to be the safety equivalent to no canopy. Any canopy that makes wearing a life jacket in- advisable should also be considered a restrictive canopy. The risks to passengers on DUKWs vary significantly depending on the DUKW vessel, the operating area, and operator diligence. The committee’s recommendations to USCG distinguish between higher risk and lower risk operations and target the most rigorous measures to higher risk operations only. The factors defining higher and lower risk operations are listed in Box ES-1. The risks listed are related to the vessel design, systems, and operating area and are considered physical attributes of the vessel and its environment that are permanent features, unless physically altered. Issues related to operations management, such as lack of proper maintenance and insufficient crew training, could be addressed by improving safety management practices that could apply to any passenger vessels and could be monitored by USCG.

EXECUTIVE SUMMARY 3 RECOMMENDATIONS The committee offers USCG the following recommendations, starting with the use of risk assessment for DUKW operations and then providing spe- cific recommendations to mitigate the hazards discussed in the chapters on flooding, operating areas, canopies, life jackets, and safety operations. All recommendations are specific to WWII DUKWs, Stretch Ducks, and Truck Ducks. Use of Risk Assessment Recommendation 1: USCG should base updates to regulations and enforce- ment practices on the risks to passengers, operators, and the environment posed by each type of DUKW in its intended operating area. Recommendation 2: USCG should use a consistent risk-assessment meth- odology, applied at the industry level, to better understand the risks to passenger safety and to allow USCG to focus regulations and requirements on those DUKW operations that present the greatest risk. BOX ES-1 Higher Risk and Lower Risk Operations Related to the Vessel Design, Systems, and Operating Area Factors Leading to Higher Risk Operations • Fast Sinking Times • Low Freeboard • Lack of High-Capacity Bilge Pump • Multiple Hull Penetrations • Engine Air Cooling Vents • Potential Exposure to High Winds and Waves • High Traffic Areas • Restrictive Canopies Lower Risk Operations • None of the Factors Above • Reserve Buoyancy, Unless in High Winds and Waves

4 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS Flooding and Survivability Recommendation 3: USCG should investigate requiring the installation of external inflatable bladders or buoyant floats, alone or in combination with internal flotation foam, to provide reserve buoyancy for DUKWs used in higher risk operations. Recommendation 4: To reduce the flooding risk from hull penetrations, USCG should investigate requiring DUKW operators to a. Permanently seal all drain plugs and valves that are not necessary for safe operation and maintenance of the vessel. b. Install carrier bearings. c. Install reliable bilge pumps of sufficient capacity to respond to flood- ing through the largest remaining through-hull penetrations, as per NVIC 1-01. Recommendation 5: USCG should require vessel operators to demonstrate that adequate engine cooling is available for the expected operating areas and risks found in that area. Operating Areas Recommendation 6: USCG should develop uniform guidance to assist Of- ficers in Charge, Marine Inspection (OCMIs) in evaluating the suitability of bodies of water for DUKW operations. Recommendation 7: USCG should develop requirements for equipment, training, and operations that leverage the National Weather Service’s severe weather alert system to reduce the likelihood that a DUKW will encounter wind and waves that exceed its operating capabilities. Restrictive Canopies Recommendation 8: USCG should require DUKWs in higher risk opera- tions to remove canopies or to adopt canopy designs that have been dem- onstrated to provide the equivalent in safety to no canopy. Life Jackets Recommendation 9: USCG should consider making the wearing of life jackets mandatory during the waterborne portion of tours run by higher risk operations.

EXECUTIVE SUMMARY 5 Recommendation 10: USCG should investigate the use of Type III life jack- ets in place of Type I life jackets. Safety Operations Recommendation 11: USCG should require that owners and operators de- velop an effective company operating and safety manual, as recommended in NVIC 1-01, that incorporates training, maintenance, and operational standards as well as emergency response plans. Recommendation 12: USCG should require, and the OCMI should confirm, that the operations and safety manual includes procedures for monitoring changing weather conditions and adjusting operations accordingly. Recommendation 13: USCG should require, and the OCMI should confirm, that the operating and safety manual includes a discussion of the number of personnel and their duties.