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It’s not surprising that Owen Clarke Design is delving into the world of the medium size IRC and ORC racing sailboats. It is after all the latest rating rule and Fast 40 designs that have steadily increased sail area, reduced displacement and so now come within our sphere of expertise. It’s unlikely any design office in the UK, and few worldwide have completed as much development and testing on hulls and appendages for high performance yachts as OC in the last twenty years. We believe we have something new to offer, a game changing winner. Any one design class yacht cannot have an advantage over a wide range of conditions. It has to have a range in which it performs best. That will always be its disadvantage when it comes up against custom or semi-custom designs optimised for local conditions and/or a particular kind of sailing. This is what is in this offering from OC for those owners who want something different and/or want to be involved in the design and build of their own custom racing yacht.

This is Owen Clarke Design's first medium size IRC ORC rating rule offshore 40 foot racing yacht design the OCD 401

Over the last decade we’ve handled numerous enquiries worldwide from potential owners attracted to the idea of sailing fast with less crew and who wanted to race predominantly in shorter distance events under their local rating rules. The demand remains for an offshore performance orientated racing boat, not a racer cruiser and only so long as all the aspects of the design that made Class 40s rate badly are removed while maintaining the all positives and advantages that class has over ‘conventional’ racing yachts and racer cruisers. The process began with reviewing weather data for various areas around the French and British coastline, the English and St Georges Channels. Since the design would also have to compete in inshore regattas information was sourced for March to November for regatta venues from the Clyde to the Solent. Our inshore study extended to the Caribbean and North America looking at Key West, Lake Michigan and Long Island Sound.

Owen Clarke Design use polars created by our VPP to compare the actual finish time of a candidate design with the TCF time correction factor corrected time as part of the performance analysis when designing yachts to rating rules.

This initial performance study entailed developing datum designs from measurements taken in boatyards and from RORC certificates for existing boats from other design offices. Race modelling using WinVPP and Router reinforced our initial impressions that for races such as the Sydney to Hobart, as well as in North West Europe, the Caribbean, including Key West and some other classic regatta locations there was likely to be a strong case for a design optimised around higher mean wind speeds. Higher than those we believe most current designs are targeted at. Conservatively we estimated a target TCC of 1,22 would put us firmly in the ballpark and so we began work on optimising the two best candidates we had developed. As part of these studies the tables above show course time comparisons in different wind speeds for windward/leeward, inshore and Olympic courses, as well as the Fastnet Race for twin and single rudder candidate designs.

This is the OCD (Owen Clarke Design) latest Class 40 Open sailboat design, Cape Racing Yachts seen at the start of the Normandy Channel Race 2019 in which she finished third

Candidate designs were also computer modelled offshore in events such as the AZAB, Annapolis – Bermuda and Melbourne - Osaka Races. The final result is two distinct designs, with the same hull type, a choice of deck layouts and with the rigs and keels in alternate positions relative to the stem. The hull and appendages are a development of successful Class 40 designs such as our #157, Cape Racing Yachts, seen above. Proven high performance, dynamically stable, both easily driven in the light as well as capable of being pushed hard in moderate breeze and in waves. On the offshore design, the forestay attaches well aft of the stem, evidence of the keel’s position further aft than is the norm in IRC to date. The J measurement is longer than typical and we willingly pay a small rating penalty for that and the 188 square metre spinnaker. The epoxy glass/foam sandwich inshore design rates 1.213 under IRC and our offshore design with the water ballast option 1.225.

Owen Clarke design are experienced in the optimisation of racing yachts to rating rules such as IRC and ORC. The OCD 401 shown here is effectively a Class 40 optimised to the IRC rule.

To discuss your project contact: OC RACING

For an explanation of the technology behind the design process go to: NAVAL ARCHITECTURE

For an insight into our engineering and detailed design work go to: ENGINEERING

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