McConaghy’s IRC 41 Racer ‘Ambush’

Our IRC 41 design currently under construction at McConaghy’s is the result of a long and detailed R&D program aimed at optimising the performance for Asian conditions both inshore and offshore.  The first boat ‘Ambush’ is for repeat clients in Hong Kong, and reflects their experience racing locally in their previous custom Mills 41, as well as their views about the best way to approach the fleet with a new design.   

The design process involved a comprehensive CFD driven VPP study with our research partners KND / Sailing Performance, looking at multiple hull shape options, foil configurations, and sail plan sizes.  This work built on our previous studies for new designs based on increasing form stability when heeled, resulting in significant gain upwind in a breeze.  The focus for this design was to ensure these gains could be combined with strength in light/medium airs, as well as breezier conditions offshore in events like the Vietnam Race.  Since these ambitions are not always mutually compatible, it became clear that including as much modability as possible into the basic boat would offer a range of benefits: firstly it provides the client a far wider range of competitive configurations by adjusting the key components of Draft, Displacement, Trim, and Sail Area.  Secondly in the light of the IRC rule’s transition in recent years towards accommodating lighter faster designs including wide modable ranges in as many parameters as possible opens up the ability to respond to future rule adjustments flexibly, extending the competitive life of the boat.  Thirdly it allowed the basic hull shape to deliver a wider range of possibilities for other clients looking to optimise future builds of the design more significantly for different conditions.  A key compnent in achieving this is a bulb/fin attachement developed from our Mini-Maxi Alegre 3 that allows quick and easy draft, displacement, and trim adjustment.

Engineering partner SDK of Rhode Island is perhaps the worlds leading composite raceboat engineer with prominent TP52 and Mini-Maxi designs as well as the current America’s Cup holder.  They have produced a refined structural layout with a focus on weight reduction, global stiffness, and ease of movement internally, resulting in a simple interior with features such as a basic galley and cooler stowage on either side of the mast, Nav seat on the engine box, and a head to Starboard forwards adding offshore functionality. 

Hull 1 in particular reflects the lead clients desire to keep the boat very simple and offshore-friendly, combining a rating conscious e-glass/epoxy/foam hull and deck construction with carbon in the high load keel structure to reduce weight and increase stiffness.  One benefit of the high quality semi-custom build process for future builds of the 41 at McConaghys is their ability to easily adjust significant items such as the deck geometry or build materials to meet clients specific requirements, or easily include basic options such as wheel steering, retracting propeller.  We look forward to discussing this design in more detail with anyone consider a new performance IRC 41