construction material. However, the modulus of elasticity is very low compared to steel and aluminium. Tis means much more elastic deformation under load with possibly undesirably large deflections and possibly a potential for harmful effects on the natural frequencies of the structure. Tis requires careful consideration to in extending the use of FRP to hulls of more than about 70 m in length.
1960 – 1980
Until the early 1960s FRP laminates were generally single- skin E glass fibre, CSM or WR, reinforced polyester. It was used extensively for smaller, high production, recreational craft where many hulls could be laminated and cured in a short time using the same female mould. In 1960, the Marine Design Manual for Fibreglass Reinforced
Plastics, authored by Gibbs and Cox, became the first major publication that addressed engineering theory for the construction of fibre reinforced plastic hulls. This Design Manual gave design criteria for both E glass reinforced single skin and sandwich laminates; design examples; design details; identified potential problem areas and enumerated mechanical properties based on test results of many different E glass fibre reinforced plastic laminates. The book was the foundation for establishing the technology of GRP as a boat building material and provided the means of extending the use of GRP to much larger vessels. The Gibbs & Cox manual gave designers guidance for
minimizing the disadvantage of low modulus of elasticity for local structure through the use of sandwich laminates, which are formed by two thin single-skin laminates enclosing a very light core material such as PVC foam. As the foam core weight is negligible, the sandwich laminate has vastly greater strength and stiffness for a lesser weight than a single-skin laminate. However, the greater number of potential failure modes of a sandwich laminate do require increased care in the design and a higher level of quality assurance during the building process. Also, the sandwich laminate has a much lesser resistance to impact damage than a single-skin laminate. Designers must take into account the drawbacks of the lighter weight hull structure, of otherwise comparable strength, against sea loads. During the 1970s, responding to industry need, classification
societies developed and published Rules for FRP hulls. In doing this, classification societies also developed standards for the building process and quality system, an important step in verifying that the constructed hull attained the required design strength. At this time, FRP was used primarily for most recreational craft, up to about 20m in length, for nearly all lifeboats, for many fishing vessels and for relatively large minesweepers.
Ocean Racing Yachts
By the late 1970s the design of sandwich laminates was well established and designers were looking at advanced
48
performance FRP materials used in the aerospace industry, such as epoxy resins and carbon and aramid fibres, which had improved mechanical and physical properties compared to polyester resin and E glass fibres. These new techniques introduced a revolution in the design of ocean racing yachts. Lighter, higher performance hulls which, for the same
displacement, allowed greater ballast in the keels, offered improved racing speeds. Designers of ocean racing yachts for category 0, 1 and 2 ocean races regulated by the Offshore Racing Council (ORC) turned to epoxy resin reinforced by carbon, aramid and glass fibres to achieve this. Te hulls were entirely of sandwich laminates, except in way of the keel structure, the mast and other critical locations where the concentrated loads were supported by thick single-skin laminates. While the use of advanced FRP laminates resulted in lighter hulls for the same strength, those same advanced composites also demanded more sophisticated design and higher construction quality assurance to realise their full potential. Inevitably there was a learning period. Not all of the potential
failure mode mechanisms for advanced composite hulls had been identified for inclusion in the design criteria available at that time. As a result, there were some prominent hull structural failures of these high performance yachts during severe weather. Tis led the ORC to decide that a structural standard was
urgently needed for offshore, ocean racing yachts constructed of advanced FRP materials, as well as conventional FRP. Te ORC contacted ABS and proposed that ABS, together with the International Technical Committee (ITC) of the ORC, develop this structural standard for offshore racing yachts. Two members of ABS and three members of the ITC developed the standard based on input from many prominent racing yacht designers. Te resulting ABS Guide for Building and Classing Offshore
Racing Yachts also included extensive requirements for the building process and quality system, recognizing this as an important component of the design strength being attained in the completed hull. Following publication in 1981, the ORC required all yachts racing in Category 0, 1 and 2 races to comply
HMS Wilton was the first warship in the world to be constructed from glass reinforced plastic
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64 |
Page 65 |
Page 66 |
Page 67 |
Page 68 |
Page 69 |
Page 70 |
Page 71 |
Page 72 |
Page 73 |
Page 74 |
Page 75 |
Page 76 |
Page 77 |
Page 78 |
Page 79 |
Page 80 |
Page 81 |
Page 82 |
Page 83 |
Page 84 |
Page 85 |
Page 86 |
Page 87 |
Page 88 |
Page 89 |
Page 90 |
Page 91 |
Page 92