Boat concept

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The K36-SAMURAI is a light-weight high performance boat designed to fit into the HPR (High Performance Rule) class of racing yachts. Suitable for both inshore around-the-buoys and offshore long distance races the design is targeted to a race oriented owner who wants to enjoy fast and fun sailing more easily and effortlessly and at a more reasonable cost than with a 40 footer race boat. The performance has been intensively studied to also be competitive under the ORC and IRC rating systems.

Although it is true that light-weight high performance boats have relatively higher ratings compared with heavier cruiser-racers especially in the medium winds around 12kts, the unfavourable difference will be a few percentage of the rating and can be overcome by the significant performance improvements available in a modern light-weight design. It is also true that the high performance boats can provide much better performance in light winds and in planing conditions and therefore get tactical benefits by sailing ahead of other boats in the fleet.

The K36-SAMURAI design benefits from ACT’s extensive CFD experience of over 20 years in the America’s Cup, with other classes of racing yachts, and also in the competitive commercial ship market, which similarly requires significant performance improvements. CFD is one of the technologies often utilized for scientific design but to achieve useful results it requires careful technique and years of experience. This technique and experience have been applied to the hull shape and appendage configuration of this new design. The hull shape has been intensively refined to have lower drag in combination with stability and power and has been evaluated by CFD at various boat speeds in downwind, including planing conditions, and in multiple upwind heel and leeway conditions. A total of more than 300 cases design simulations were run to finalize the shape. The keel position was optimized to achieve the best trim over a wide range of wind conditions by considering the changing of LCG position with varying crew placement. The rudder position was studied to give good yaw balance and enough lift force to enable easy handling.

The specifications were determined by careful study of the VPP results, consideration of the applicable IRC and ORC rating systems, and comparisons with multiple recent HPR designs. The maximum beam was chosen to keep the stability well balanced with the sail plan and displacement.

The deck arrangement was designed to be as simple and spacious as possible with crew ergonomics considered over a range of crew positions to allow optimal fore-and-aft trim. All control lines except vang line are led above deck without any holes into the interior to avoid water intake keeping the interior dry for both comfort and to avoid unnecessary weight.

To achieve the best structural arrangement for a light and stiff hull SDK Structures LLC has drawn upon their extensive experiences in light-weight high performance race boats engineering. Structural ideas have been borrowed from the competitive TP52 and Maxi 72 classes and scaled down to suit a 36 ft yacht. The structure is designed to satisfy the ISO Category A and ISAF OSR Category 1 to ensure years of competitive racing in potentially rough conditions.

The Pauger Carbon Ltd is the builder for both of the boat and rig. Pauger has years of experience in building both carbon composite racing yachts and high performance carbon rigs. Drawing on this experience they are infusing the hull and deck in female molds using high strength carbon fiber and Airex structural foam core. The interior structure is also of carbon and foam and the majority of the carbon is unidirectional material for optimal strength, stiffness, and fiber content. The keel fin is fabricated of high tensile steel with composite fairings to provide a low VCG.