Design № 685
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The Class 40 fleet has undergone explosive growth in recent years by filling a market niche for fast, high performance offshore capable boats that are well suited to short-handed sailing. The class is governed by a strict set of rule controls that limit the principal characteristics of the design with an effort to tightly control costs and produce equitable performance between boats.
At Farr Yacht Design we have been watching developments in the Class 40 arena with interest for some time, looking for the right opportunity to bring our extensive Volvo Ocean Race and Open 60 offshore design experience to bear on this exciting class. In October 2009 we contracted with Lapo Ancillotti’s BTBoats of New Zealand to develop a new limited production Class 40 design to be constructed in New Zealand by Cookson Boats.
An intensive computational fluid dynamics based hull development program was undertaken to evaluate a number of candidate hull styles exploring the performance effects of chines, transom immersion, longitudinal hull shaping and section style etc. The results from this work, combined with our Open 60 and Volvo Open 70 design work have resulted in a hull that approaches the maximum beam allowed by the class and incorporates prominent chines over the length of the boat producing a shape well suited to high speed sailing. Significant focus has been applied to developing a hull shape that handles itself well in all sea states in order to maintain consistently high average speeds in long distance racing even in the worst of conditions. The water ballast tank placement has been optimized for maximum stability and longitudinally placed to provide trim adjustability.
This design has been carefully refined to meet the Class 40 rule requirements including Category 0 compliance from the outset. A detailed focus on the construction process and engineering of the yachts structure has allowed us to reach the minimum rule displacement and maximum 90 degree pull down test requirement placing the boat in the optimal position relative to the rule limits.
The deck geometry and deck layout incorporate input and feedback from a variety of areas to produce a clean, functional and ergonomically efficient arrangement well suited to short-handed sailing in distance races. The arrangement incorporates the dual companionway, central line tunnel concepts originally pioneered on our Open 60 Design 498 - Virbac Paprec, and a winch layout specifically suited to the unique Class 40 rule restrictions and demands. Careful attention has been paid to developing an ergonomic deck layout and efficient steering systems to maximize the ability of the crew to hand-steer and trim the sails easily. The waterballast control systems have been designed to allow operation from sailing positions on deck. A removable rigid dodger has been developed to enhance crew protection for long distance racing.
This logic has been extended through to the mast design and rigging layout where significant emphasis has been placed on maximizing the crew’s ability to control the sail trim and mastbend. This is highlighted by the selection of a keel stepped mast with a boom vang arrangement to improve mainsail control. The mast is a 2 spreader highly swept carbon mast with chainplates located inboard to allow sufficiently tight sheeting angles for the Code 0 sails. Detailed studies of sail sizes and parameters have been completed to develop a well balanced sail plan with appropriate head stay control. Care has been taken to develop an even usage profile over each of the sails to maximize sail life and to develop candidate inventories appropriate for different racing conditions. The boat has an articulating bow sprit fitted that has been closely engineered with the headstay attachments and pulpit to produce an elegant solution that can be easily operated even when under full sail loading.
The interior arrangement has been designed for racing functionality with ample berths, head and galley for offshore races. A tacking navigation station is fitted to allow crew weight placement outboard even when navigating. The interior features the 4 rule required fixed bottom berths that will be supplemented with pipe berths when racing. The head is located forward of the mast frame.
The keel is built from fabricated steel with a fiber glass fairing attached to a squished lead bulb. The keel attachment has been engineered to simplify boat assembly. The design features twin rudders with a direct linkage steering system with a single tiller.
The initial sea trials for the boat have been overwhelmingly positive and we are excited to see how she stacks up against the other top contenders in the class in the coming months.
PHOTOS Click to enlarge.