Pleased to have played a key role in the development of the highly sophisticated sailing yacht Hamilton, the UK-based composite engineering specialist STRUCTeam (STRUCTural Engineering for Advanced Materials) is celebrating her successful launch. The Hamilton superyacht is the first of the revolutionary new 100‐foot WallyCento cruiser racers by Wally Yachts.
With advanced composite materials playing such a major part in the construction of the 100ft luxury yacht Hamilton, STRUCTeam was invited by builder Green Marine to contribute its unique expertise in the structural design of composite yachts and other structures. Key elements were optimisation for both weight and performance, although cost and production engineering were to be taken into account.
The accumulated experience of STRUCTeam’s staff covers boats from America’s Cup contenders and Volvo 70s to Maxis, TP52s and a number of super yachts up to 200 feet. Just as for those craft, the structural design of Hamilton is critical to her success as both a cruising and racing yacht, with the primary objective of delivering a dependable and consistent structure of minimal weight.
The challenge for STRUCTeam was to engineer a structure that maximised the internal volume to accommodate the cruising interior while being capable of handling racing yacht loads (the compression load on the bowsprit is greater than 80 tonnes, for example). With reduced internal structural options the materials had to provide the necessary strength and rigidity. An additional factor that had to be taken into consideration was complexity introduced by the many rams and control systems for handling the sails that are required under the Wally rules.
The initial pre‐study phase produced a structural concept and specified the laminates for all the major components (hull, deck, keel support structure, mast support structure etc). This process involved working directly with Germanischer Lloyd (GL) on the development of the new “GL Guidelines for Racing Yachts, 2011” applicable to yachts over 24m such as the Wally Cento.
At this stage conceptual feedback was also provided to ensure that the proposed internal structure and layout did not conflict with the performance brief. STRUCTeam’s experience with high performance racing yachts and lifting keels was invaluable here. With that completed, STRUCTeam was further appointed by Green Marine to undertake the detailed engineering.
For the laminate engineering various “standard” laminates were built and their properties analysed using ESAComp software. The engineering team then applied these to the various components of the structural model and optimised them according to the projected loads. Once the structural engineering was completed the critical elements were appraised using FEA (Finite Element Analysis), as were the keel attachment and support structure, the bowsprit, the mast support structure, and the mainsheet bulkhead.
Other specific structural items, such as the rudder and composite chain plates, were engineered using in‐house detail engineering routines that STRUCTeam had written in order to be able carry out analysis and design tasks in an efficient manner.
To ensure a good level of global stiffness in the build, intermediate modulus fibres (circa 290GPa Modulus) were used for the hull, bottom and side decks. The remainder of the structure utilised standard modulus (circa 240GPa modulus) and high strength (>4.9GPa) carbon fibres, all in prepreg format.
The selection of the materials for the core was determined by weight, stability, stiffness, fracture toughness and impact resistance to slamming loads. The result was that a mixture of Kevlar honeycomb, Nomex honeycomb and high elongation structural foam was used both in the hull and deck. For the internal structure a combination of Nomex and Kevlar cores was specified.
“To meet the Wally ethos of Grand Prix racer meets luxury cruiser, and on such a large scale, was an exceptional challenge,” said STRUCTeam’s Julien Sellier, “and it was a privilege to have a leading role in achieving it on the first boat of a new class. The staff at STRUCTeam fortunately have both the experience and the tools to undertake projects of this complexity and it is immensely satisfying to see her out of the shed and preparing for the Superyacht Cup. We wish her owner and crew every success out on the water, and look forward to seeing the class grow and flourish.”