Owen Clarke One Design IMOCA 60 proposal

Is this really the future for the solo round the world class?

Wednesday March 21st 2012, Author: James Boyd, Location: United Kingdom

Owen Clarke Design presented to the executive of IMOCA and their own skippers/owners a report on the design and build costs (with information provided from two leading Open 60 yards) of a one design IMOCA 60. This, along with a generic design was presented before the meeting in Lorient in February 2012 at which some of the members of IMOCA discussed the way for ward for the class after the 2012 Vendee Globe. This discussion included this option as one of the possibilities among others for the future development of the class.

It’s apparent that from feedback we’ve had from outside this initial group that at least some portions of the report have been circulated to other design offices and sailors, which was part of the purpose of undertaking the work. With over a month since the meeting it now feels appropriate to distribute our findings more widely to fuel debate on this important decision, for what has been for many years the world’s premier offshore development class.

Owen Clarke Design IMOCA Mono-type, Design #18


- Pre-preg carbon and Nomex construction
- Stainless steel, twin hydraulic ram system
- Forged high strength stainless steel keel with composite fairings
- Canting keel fixed to max 40 degree cant. No ten degree, simplifies greatly measurement system
- One central aft ballast tank, 1500 litres, One central fwd ballast tank 1500 litres
- Rig, 27m above deck, carbon three spreader rig with discontinuous carbon rigging
- Shorter SPL, J, and I used to calibrate performance in different conditions and control cost/ease of use
- No bowsprit, gennakers and spinnakers tacked off the end of the ‘dreadnought bow’


Length overall 19.2m
Beam overall (withheld)
Draft 4.0 m
Displacement 8.9 t


The performance of the yacht was matched using our in-house VPP which was recently calibrated using the six 1/7th scale and one 1/3rd scale model used in the design of our 2011 Open 60, Acciona 100% Eco-Powered

By developing from the original Acciona model we were able to produce a yacht with the same performance within a few hours on a simplified Vendee Globe course. The work completed was sufficient to confirm the feasibility of the design and included the use of the race modelling program Router. A full design development program would be required to produce a final design.

WinVPP and the systematic analysis approach (as described on our web page Naval Architecture was used to develop each of the candidate designs.


We have not provided budget figures for the additional cost required in order for a new OCD IMOCA monotype to be 100% eco powered with zero emissions as per Acciona. However, we would assume the class would want lead the way in international yacht racing and to into this technology and the marketing potential either in monotype or otherwise for future IMOCA class yachts.

Budget costs

Owen Clarke approached two builders, one in the Southern Hemisphere with a specification for the yacht and asked them to produce build costs for new Open 60 designs and an IMOCA monotype based on the OCD design, including female moulds and on the basis of producing initially three to four boats.

Costs include design, yacht sailing (including first suit of sails/electronics) in Europe (including shipping from New Zealand) up to the end of builder’s trials. What is excluded are project costs such as management, office, salaries, travel and accommodation.

Euro 2,765,417 Build, New Zealand (conventional power) - Sailing in Europe at trials

Euro 2,967,759 Build, Europe (conventional power) – Sailing in Europe at trials

This compares to the build of a new OCD IMOCA Open 60 at Southern Ocean Marine, sailing in Europe at sea trials of:

New build in NZ from the same mould as Acciona (conventional power) : Euro 2,875,914

New build in NZ from a new mould and new design (conventional power): Euro 3,054,434

Although the two yards we supplied build materials and design drawings to were Southern Ocean Marine (New Zealand) and Green Marine (UK) we would welcome building a new OCD boat in France. The only reason we did not submit our design to the yards in France for the moment was one of confidentiality. We would very much like to have one of our yachts built in France, but although we began our 60 career by project managing the construction of an Open 60 in France, as designers none of our yachts have been built there yet. Despite having designed eight of the modern IMOCA 60’s (more than any other design office) and having had clients from Switzerland, Spain, New Zealand the UK and Canada, we have never yet designed a yacht for a French client. We hope that will change. Indeed, should creating a monotype be the final decision by IMOCA members OCD would co-operate on a joint design with other naval architects to see the yachts built in whichever shipyard/s might be selected.


Clearly there are other positives and negatives to be considered in the argument of whether to go to a mono-type design other than the overall budget build costs. We have not considered here project costs, ongoing maintenance, depreciation and the myriad of other issues that need to be taken into account.

In this presentation I have considered only the technical and budgetary comparisons for the desighn and build. These have however been considered on an apples for apples basis by ourselves and two very experienced builders, based on the construction of one off and production/semi-production build methods.

The situation may best be summed in these words by Geoff Stock of Green Marine in the UK who built the hulls of Foncia/Macif:

“I think that if we want to take a significant amount out of the build cost we'd need 6 or 8 boats. The problem is that to get costs down you need to make more and better tooling; but as you know the pay-back for tooling is about 3 boats which is what we’ve considered. I guess there would be an hours reduction when making a series of boats - but really only a few percent when looking at boats 2 and 3. We built two TP52 last winter and found that the overall hours for the second boat were higher because we were under pressure of an extra tight schedule. Clearly 8 boats in a row is a different matter. “

OCD Conclusion

In boat cost terms alone (ignoring political and commercial considerations which are the domain of IMOCA/sponsors) there seems little incentive from a technical or commercial cost to revert to monotype.

The alternative should also be considered, ie: to tighten up the existing rules by the introduction of some or all of the following:

- One design fin and bulb and/or mandatory forged steel fin with fairings.
- One design rudders
- One design daggerboards
- Mass and vcg rule for masts
- Revert back to AVS 108 degrees for the fleet. Do not grand-father 2008-2010 generation

This is not an exhaustive list of course, but may go a long way to at least restrict the rate of escalating costs. They would also potentially improve a great deal the projects costs from loss/damage, as well as the safety of the fleet.

Read more about the prospect of the IMOCA 60 going one design in our interview with Class President Luc Talbourdet here, and our interview with Merf Owen here.

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