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www.sname.org/sname/mt April 2013 is process usually involves buckets of catalyzed resin that are used to wet out the reinforcement while operat- ing under a time window before the resin hardens. Brushes and rollers are used to apply the resin and special ribbed rollers are used to consolidate the laminate and remove air bubbles. e quality of the laminate is very dependent on the skill of the laminator and workers are exposed to vola- tile organic compounds (VOCs) present in the styrene-base resin system, which are suspected to be carcinogenic. Some builders realized that a vacuum bag placed over the laminate would help to consolidate it, especially when trying to bond cores in place. In 1990, Bill Seemann took the process one step further by placing the vacuum bag over a dry stack of reinforcement and using the vacuum to pull resin into the laminate. His biggest challenge was to keep the laminate from sealing itself o under vacuum so he invented what today we call ow media? to distribute the resin. He dubbed the technique the Seemann Composite Resin Infusion Process or SCRIMP, which today has evolved generically into resin infusion. Laminates produced using this method have uniform thickness, high ber and low void contents, and do not expose workers to VOCs. The aerospace industry requires even lighter, high- performance laminates in smaller quantities than boats or ships. ey typically use reinforcements that are pre- impregnated with partially cured resin, or prepregs. e prepregs are transported and stored in freezers to main- tain the state of partial cure; heat is applied only after the prepregs are placed in the mold and consolidated under vacuum. e consolidation or debulking? process often has to be done in stages, adding additional labor costs. Prepreg construction is used for high-performance racing boats but is not practical for marine applications with very large surface areas. Early berglass boat construction was truly like taking a time machine trip back to the Wild West. Some people made a lot of money and a lot of great discoveries were being made but the rule of law, or design guidelines, was missing. e term best practices? had yet to be invented, which contributed to the boom or bust mentality. Often spurred by material suppliers or end-users, the marine composites industry silenced early critics by systemati- cally addressing design, manufacturing, and in-service performance issues. Design tool development e rst berglass boats were designed using a trail-and- error methodology, which led to some early failures; but more often, it resulted in boats that were built heavier than necessary. is was not always a bad thing, as boaters nd ways to land themselves on the rocks or otherwise push their vessels beyond their intended service. Without the fty years of hindsight we now have, nobody truly knew how long these structures would last. Indeed, one of my favor- ite anecdotes about my dads rst berglass boat, a Block Island 40, has its designer, William Tripp Jr., repeatedly driv- ing over a test panel with the family car to prove how tough the hull would be. It must have worked, because I just saw the boat listed for sale 55 years after she was built (at six times what my dad paid for her). In 1960, Gibbs & Cox produced the Marine Design Manual for Fiberglass Reinforced Plastics , which provided insight on how berglass materials of the day performed as boat structure. Design details and laminate properties were presented via graphs and tables and this served as the primary design resource until the American Bureau of Shipping codied its Rules for Building and Classing Reinforced Plastic Vessels in 1978. ese prescriptive rules for plating thickness and scantlin g sizing produced designs that would be considered conservative by todays standards. Classical laminate theory (CLT) considers laminates as plies with unique strength and stiness characteristics that At approximately 900 tons (out?tted), the DDG 1000 destroyer deckhouse, an integral feature of the new Zumwalt-class destroyer, is claimed to be the largest composite structure ever built. Photo courtesy Huntington Ingalls Industries, Inc.