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January 2012 www.sname.org/sname/mt changes in the way of plating and framing thickness result- ing from the selection of high strength steel. Bollinger chose to use higher strength steels, such as AH-36 steel, in the FRC and was thus able to take advantage of the increased strength of the hull material and reduce plating and stiener thicknesses, while optimizing the design to the ABS HSNC Rule requirements. Significant weight sav- ings were achieved in the hull plating where the company was able to reduce plating thicknesses. Osetting these savings, however, was the additional weight of added watertight bulkheads due to floodable length consider- ations, heavier equipment foundations due to the higher power ratings of the main engines and gears, and the addition of weapons foundations not found on the parent craft. e primary reason that high-speed craft fail to perform is an unantici- pated increase in the weight of the craft. To reduce the risk of this happening, Bollinger did an analysis of the parent craft?s inclining results, showing that it was less than 1% dierent from the parent craft?s weight estimate, thus verifying the parent craft weight estimate. e company also prepared a lightship weight estimate based on the dierences between the FRC design and the Damen parent craft, to ensure that the FRC lightship weight esti- mate is accurate. Bollinger used a combination of higher-strength hull steel, lightweight outfitting, and removal of parent craft equipment not required by the COR to reduce lightship weight. These tech- niques proved effective in the 87 foot WPB program. The company also accomplished a thorough review of the applicable ABS classification require- ments, and adjusted the design and weight estimate to suit. The parent craft has an endurance of 14 days and a range of 3500 nautical miles. The vessel operates in the South African Exclusive Economic Zone, an area of the Southern Ocean, which can experience extreme weather conditions during the winter months. Thus, the parent craft had a heavily-built hull structure, with considerable stores space. Its fuel oil capacity was greater than that required for the FRC. In addition, a firefighting sys- tem, which includes a large dispersant tank, is also fitted on the parent craft. Optimization of the hull structure to ABS HSNC, elimination of the firefighting system and associated dispersant tank, reduction of the fuel capacity, and opti- mization of outfitting enables Bollinger to incorporate all the features required by the COR and still meet the maximum draft limitation of 3.05 m. e result is that the FRC full load dis- placement diers by less than 1% from that of the parent craft, which contributes to successfully achieving the speed/power performance. In addition, while incorpo- rating the changes required to satisfy the COR requirements, Bollinger was able to carefully manage the location of the cen- ter of gravity of the FRC design so that the longitudinal center of gravity and trim requirements are met. e Damen parent craft was designed to meet the International Maritime Organization A749 standard stability crite- ria, surviving one-compartment damage. To meet the required two-compartment standard of damage, it was necessary to rearrange the below-deck spaces, intro- ducing three additional transverse bulkheads. e FRC design also increased the sheer aft compared to the sheer line of the parent craft. MTDennis Fanguy is vice president of quality manage- ment system at Bollinger Shipyards, Inc., in Lock- port, Louisiana. þÿ AA United States þÿ NNavy 179-ft. Cyclone class patrol boat, the original design of which was developed by Bollinger from a Vosper Thornycroft in-service parent craft. e coast guard initiated the acquisition of the Marine Protector class of 87-ft. coastal patrol boats (CPB) in 1993 to replace the aging 82-ft. Point class patrol boats. 26_31_FanguyFRCfeature_SNAME_Jan12_P3.indd 3112/22/11 3:37 PM