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The 47-Foot Motor Lifeboat By the early 1980s, the Coast Guard began to recognize that the venerable 44-foot motor lifeboat was nearing the end of its service life, having seen two decades of heavy use in severe weather and sea conditions. In addition , since the time the 44-footer was designed, there had been a significant increase in non-rescue, law enforcement missions. As such, the Coast Guard was going to require a higher-speed, more multimission-capable lifeboat design than the 44-footer to facilitate its use in missions other than just search and rescue, i.e., in more of a utility boat role. In July 1985, the Coast Guard’s Boat Construction and Maintenance Branch issued a concept design proposal that was circulated among lifeboat stations as well as Headquarters staff for comment.1 In parallel, the Coast Guard also examined modern lifeboat designs from foreign lifeboat services to evaluate desirable features. Specifically, the RNLI was solicited for input from their experience with the Arun-type fiber-reinforced composite-hulled lifeboat, as well as the German Lifeboat Institute and Norwegian Society for Sea Rescue for input from their experience with their rescue cruisers (steel- and aluminumhulled , respectively). Following the receipt of initial comments from the field, a revised version of the design report was provided to the boatbuilding industry for comment since, by this time, the Coast Guard had determined that they were going to have such boats constructed by commercial boatbuilders rather than by the Curtis Bay Yard. The concept design called for a boat with the following enhancements in design and performance: Larger size than the 44-footer to improve seaworthi- • ness (with higher initial stability), but with limitations such that lifeboat stations would not have to expand boat mooring and repair facilities All-aluminum, hard-chine, deep-V planing hull for • higher speed and reduced rolling motion, rather than a soft-bilge, semi-displacement hull such as the 44footer , with an aluminum cabin and stainless steel fittings More powerful and automated diesel propulsion en- • gines to provide for higher speed for better surf avoidance and shorter transit times to a rescue case location Better protection for crew, with both open and en- • closed conning stations, to reduce fatigue and exposure during heavy-weather missions Four boat-control stations for better redundancy and • flexibility Better layout and electronics for multimission capa- • bility Port and starboard hull/deck recesses for easier res- • cue of persons in the water Slanted forward cabin windows to improve strength • and visibility, as well as to lessen glare2 This motor lifeboat was to be the first U.S. lifeboat design to incorporate multimission tasking such as law enforcement and military operations, and was one of the first acquisition projects in the Coast Guard to fully incorporate all the improved practices that had been developed by the U.S. Department of Defense for major acquisitions . It was also the first American lifeboat design with an aluminum hull, which initially raised concerns regarding hull strength and durability as compared to the Corten steel hull of the 44-footer. Up to this point, the only major class of boat that had been built by the Coast Guard out of aluminum was the 41-foot UTB, and 7 The Coast Guard Today 126 The Coast Guard Today stress cracks had occurred in some of the hulls of this type craft. Beginning in 1986, the Coast Guard began initial testing of the concept design with a ⅛th-scale model in towing tank and stability experiments conducted at the U.S. Naval Academy, as well as a full-scale wooden superstructure mock-up constructed for testing of humanequipment interfaces and layout. Finally, in 1988, the Coast Guard awarded a $6.7 million contract to Textron Marine and Land Systems (TMLS) for the construction of a full-scale prototype boat, with options for the construction of five other preproduction craft. This boat, CG47200, was completed in July 1990 and delivered to the National Motor Lifeboat School for an eighteen-month period of developmental testing and evaluation (DT&E) by a group of highly qualified and experienced MLB coxswains and surfmen that had been assembled for this purpose , as well as representatives from the Coast Guard Research and Development Center. Testing was assisted by the use of special electronic equipment installed on the prototype boat to collect data on boat motion and performance . The feedback from this testing was to be incorporated into the modified design for...

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