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

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7 Three DUKWs, amphibious passenger vessels used for commercial tours, have sunk with passengers on board since 1999. In total, across the three major marine casualty events, 32 people have died, including a number of children. The most recent sinking, the Stretch Duck 7 while touring on Table Rock Lake near Branson, Missouri, in 2018, took 17 lives. DUKWs in commercial service in the United States currently number about 200 vessels, under the jurisdiction of either the state of Wisconsin or the United States Coast Guard (USCG).1 USCG’s jurisdiction over DUKWs extends only to their water operations and is part of the agency’s regulatory oversight of vessels that engage in commercial operations on the navigable waters of the United States. USCG administered regulations aim to ensure that passenger vessels under its jurisdiction operate safely with minimal risk of death or injury to passengers and operating crew. The original DUKW was designed and manufactured for military use during World War II. After the war, surplus DUKWs were used for tour opera tions as early as 1946. A surprising number of WWII DUKWs are still in service today, and tour operators often celebrate the vessels’ his- tory and ties to the military. In the 1990s and 2000s, two variations of the WWII DUKW came into use. Stretch Ducks and Truck Ducks up- dated the WWII design for use in the commercial touring industry. USCG sought recommendations from the National Academies of Sci- ences, Engineering, and Medicine (the National Academies) on improving 1 The DUKWs under state jurisdiction in Wisconsin operate on non-navigable waters of the United States. 1 Introduction

8 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS the safety on navigable waters of all three types of vessels, collectively referred to as DUKWs. In response to its charge, the National Academies appointed an expert committee to produce this report, which considers and offers recommendations on candidate technologies to prevent flooding and to keep DUKWs afloat and upright, criteria for evaluating the safety of operating areas, design options for improving the safety of canopies, re- quirements for life jackets, and other means to improve the safe operation of DUKWs. The committee also recommends that USCG use a consistent risk-assessment methodology to evaluate the risks of each type of DUKW. STUDY ORIGINS, CHARGE, AND APPROACH In response to the sinking of the Stretch Duck 7 in 2018 and the long history of discussions regarding DUKW safety, the USCG Assistant Com- mandant for Prevention Policy (CG-5P), Office of Design and Engineering Standards (CG-ENG) asked the National Academies to provide guidance to USCG on steps that could be taken to improve the safety of DUKW vessels. Specifically, USCG asked that this guidance be based on a review and assessment of investigations of past casualties involving these vessels; technical studies of vessel modifications having the potential to reduce the risk of casualties; and any enforcement and operational changes that may be required to implement the modifications. The full Statement of Task is provided in Box 1-1. In seeking this guidance, it asked for suggestions on places where USCG regulations and policy documents could be modified to implement one or more of the identified options. At the request of USCG, the committee focused only on the DUKW type of amphibious passenger vessels. Other amphibious vessels have dif- ferent designs, are fewer in number, and have not experienced similar levels of casualties and injuries as the DUKW vessels. The committee only considered in-water operations. Issues related to over-the-road operations were not part of the study. The National Academies formed a committee to respond to the USCG Statement of Task and to provide the desired industry and engineering input on how USCG could improve DUKW safety. The members of the committee and their backgrounds are listed in Appendix A of the report. Public Meetings The committee began its work in January 2021, and all but one of its meet- ings were convened virtually because of the COVID-19 pandemic. While the virtual meetings had drawbacks, including constraints on interactive discussion and a spread in time zones, they did allow for a larger number of briefings. The committee was able to use these many opportunities for

INTRODUCTION 9 briefings, as well as requests for more detailed follow-on correspondence, to take a multi-pronged approach to the study. The committee conducted three meetings open to the public where it received briefings from industry and the sponsoring agency. Meeting dates and presenting organizations are as follows: January 22, 2021 Representatives from the USCG Commercial Regulations & Standards Di- rectorate, Office of Design & Engineering Standards, Naval Architecture Division, reviewed what they were seeking from the committee, provided background on the topic, and discussed the data they could make available. They also responded to written and verbal questions from the committee. January 25, 2021 Boston Duck Tours representatives presented an overview of their company, its operations, and the many measures they have taken to improve the safety of the DUKW vessels they operate. They also responded to questions BOX 1-1 Statement of Task A study committee appointed by the National Academies of Sciences, Engineer- ing, and Medicine will review the safety record of amphibious vessels (DUKW boats) when used for commercial passenger service and identify options for improving their safety performance through changes in vessel design, engineer- ing, and outfitting. The committee will review findings and recommendations from investigations of casualties involving these vessels by the National Transportation Safety Board, the United States Coast Guard, and other marine safety authorities in the United States and abroad. It will examine the results of technical studies of options for vessel modifications to reduce the risk of a casualty and increase the potential for crew and passenger survival. The committee may also explore other related options that deserve consideration, including any enforcement and operational changes that may be desirable to implement vessel modifica- tions. The committee will summarize the options in terms of the risks they can mitigate and the ways in which the use and operation of DUKW boats could be impacted. Based on its expert appraisal, the committee will identify and sug- gest places where Coast Guard regulations and policy documents could be modified to implement one or more of the options, such as in the Navigation and Vessel Inspection Circular 1-01 (Inspection of Amphibious Passenger Carrying Vehicles).

10 OPTIONS FOR IMPROVING THE SAFETY OF DUKW TYPE AMPHIBIOUS VESSELS from the committee. Following the meeting, Boston Duck Tours sent further information on the design of their Truck Ducks and the safety measures they have implemented. March 19, 2021 A representative from the Passenger Vessel Association (PVA) made a pre- sentation describing the DUKW operators who are members of PVA and highlighted the many studies and meetings sponsored by PVA to facilitate communication and understanding between USCG and PVA members and to improve the safety of DUKWs. The presentation provided an overview of pending legislation on DUKW vessels2 and suggested areas of focus for the committee. Also, the former owner of the Chattanooga Ducks presented his knowl- edge and thoughts on DUKW operations, safety concerns, and remedies im- plemented by his former company. Chattanooga Ducks operates four WWII DUKW vessels on the Tennessee River along the Chattanooga waterfront. The information presented by industry during the open meetings helped the committee to understand current DUKW operations and the many mea- sures industry has taken to address the safety concerns with these vessels when operating on the water. It also helped the committee understand some of the challenges faced by the operators in implementing additional safety measures. USCG provided valuable information on the many studies undertaken over the years and provided valuable fleet data and prior studies, USCG recommendations and responses to the prior casualties, and National Transportation Safety Board (NTSB) recommendations from casualty inves- tigations.3 The committee had access to the NTSB and USCG investigation reports on previous casualties, studies done by USCG on DUKW flotation after flooding, and USCG studies on DUKW intact and damage stability. Because DUKW type vessels are also operated in other countries, the com- mittee had access to the United Kingdom’s Marine Accident Investigation Branch investigation reports on DUKW casualties and Canadian govern- ment casualty reports. 2 S.62 - Duck Boat Safety Enhancement Act of 2021, introduced January 7, 2021, https:// www.congress.gov/bill/117th-congress/senate-bill/62/text; and S.1031 - Duck Boat Safety Enhancement Act of 2020, passed by Senate December 10, 2020, https://www.congress.gov/ bill/116th-congress/senate-bill/1031. 3 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.

INTRODUCTION 11 In addition, the committee reviewed designs for reserve buoyancy and canopies used on DUKWs overseas and in Wisconsin, where DUKWs operate under state jurisdiction, as well as vessels that are purpose built amphibious touring vessels. REPORT ORGANIZATION The rest of this report is divided into an overview chapter, five subject-spe- cific chapters, and a final chapter that presents summary findings and rec- ommendations. Each subject-specific chapter reviews major casualty events from the perspective of the chapter’s subject, examines regulations, and evaluates potential solutions. Chapter 2 provides an overview of DUKW boats and their regulation and introduces the major casualty events on water that the committee studied, as well as the findings from casualty data. Recommendations from casualty reports from the United States and the United Kingdom are reviewed. The chapter closes with an overview of survivability, including how the concept applies to DUKWs and their operations. Chapter 3 examines the intact stability of DUKWs, methods to increase reserve buoyancy to keep a DUKW upright and afloat, and solutions to pre- vent flooding through hull penetrations and engine-cooling air vents. Chap- ter 4 examines why certain bodies of water pose higher risk for DUKWs and how to make the evaluation of operating areas and operating restric- tions more rigorous and objective. Chapter 5 explains why canopies are both an important part of DUKW touring businesses and an impediment to the survivability of persons on board. The chapter then reviews canopy designs currently in use and potential designs that are likely to increase the survivability of persons on board during sinking events. Chapter 6 reviews the data for increasing safety by requiring the wearing of life jackets, the difficulties posed by the requirement that DUKWs carry Type I life jackets, and the potential for Type III life jackets to provide more safety. Chapter 7 looks at the human side of safety on DUKWs, covering the number of personnel, crew training, and passenger responsibilities. Chapter 8 presents the committee’s summary findings on higher risk operations, lists the committee’s recommendations, and, in support of the committee’s recommendation that USCG use risk assessment to assess DUKW safety, provides examples of risk-assessment methods.