North Technology Group Design Project - Carkeek HP 40 DECISION

Transcription

1 North Technology Group Design Project - Carkeek HP 40 DECISION By Steve Benjamin and Chris Williams We have been working together - as salesman and designer - since In those days we worked for Banks Sails USA, which was purchased by North in Having been through many projects we are well versed in most everything required for success. However, the DECISION Carkeek HP 40 was one of the most challenging and exciting projects so far. DECISION powers over her Class at the start of Race 4 at the LVSB with3di Inshore Main & J1.5 Photo by Dobbs Davis DECISION was conceived in July-11 as the first boat to be built to the new High Performance Rule (HPR). The HPR has a very simple promise - to fairly rate high performance racing yachts. Since the new rule was not complete, it was determined to proceed with the fastest offshore capable forty foot monohull racing yacht that

2 could reasonably be built (with fixed ballast and non-power winches). Several competitive designs were reviewed and the Carkeek Design Partners plan was selected. Discussions were held with numerous yards and McConaghy China was chosen as the builder. The hull mold was started in September-11. Next came the deck plan, sail plan, rig plan, and a thorough CAD combination of the entire project (more on that later) to optimize every detail. To reach the goal of achieving the highest performance possible a total integration was performed by Shaun Carkeek, Chris Williams of North Sails, Trent Justice of Southern Spars, and Brian Fisher of Rig Pro. 3Di upwind sails, TPT technology in the rig, EC6 carbon rigging, and a complete running rigging package by Rig Pro exemplify the North Group's latest technology employed on the project at every level. We were able to call on North's vast experience with similar racing yachts including the Melges 32, MC 38, Farr 40, Farr 400, GP 42, RC44, and TP52 among others. The shapes and tuning systems developed for these boats were analyzed in the development of the DECISION Carkeek HP 40 project. A full tuning study was completed for the Carkeek HP 40 to insure that the mainsail was designed to fit the rig rather than tuning the rig around the sail. Chris Williams and Jonny Knopp (Southern Spars Mast Designer) had just recently completed designing the Farr 400 Mast, also built at Southern Spars Cape Town. The specifications for the Carkeek HP 40 rig were focused entirely on producing the fastest possible mast without regard to the CSA (Caribbean Rule), IRC, ORC or ORR rules. Therefore, as with the Farr 400 mast, the topmast runners were slid down the rig to reduce bending moment, weight, and topmast deflection to windward. Backstay deflectors were also added - in conjunction with the Carkeek HP 40's wide chainplates and the tube's TPT construction the combination allowed for a stiff, yet very lightweight mast that easily achieves high headstay tensions. Careful attention was paid to the righting moment and wetted surface ratios relative to the latest Transpac 52 fleet (currently the most similar yachts to the Carkeek HP 40). Counter to the common perception, the latest TP52's have quite deep sails due to their very high righting moments. The genoa designs combined a deep draft forward shape with quite straight backs to allow for very tight five degree sheeting angle. The downwind sails are a development of lessons learned in the 2011 MedCup - primarily that forgiving asymmetrical shapes allow the trimmer to ease the sheet further, thereby helping the sailors to mode the boat in both high or low modes. By using Dropbox, Steve has easily been able to post photos of all the sails daily so that Chris can continue to develop the sail shapes further for the next generations. DECISION's hull was shipped to St. Maarten from Zhuhai, China, the rig was shipped from Southern Spars Capetown, and the sails were shipped from Milford, CT. Clearly there was no room for errors as all the components had to fit precisely together into an optimized package, and be ready to race a few days later! St. Maarten is one of the best Caribbean destinations to commission a new racing yacht. North Sails agent Ernst Looser runs the Tropical Sail Loft in Simpson Bay and is a reliable and efficient resource. On 18-Mar-12 Stephen Murray and Stephen Murray Jr. christened their new Carkeek HP 40 DECISION at the Saint Maarten Yacht Club. The sail trials for the new North inventory had already begun, in preparation for the new boat's first two events: the International Rolex Regatta (IRR) at St. Thomas and Les Voiles de St. Barth (LVSB).

3 Stephen Murray Jr. christening DECISION Photo by Steve Benjamin The Southern Spars mast was set up with dock tuning according to Chris's rig study and tuning guide. As the sail trials proceeded we quickly made many enhancements to the rig tuning to improve the mast/sail combination and to provide more rudder angle and lift. Basically, the mast step was moved forward and the headstay lengthened to increase the rake of the mast and add windward helm. By moving the mast step forward we also reduced the bend in the lower section of the mast, making the mainsail more powerful. Tuning the Carkeek HP 40 is simplified with hydraulic headstay and topmast backstay deflector controls. There is also an integral hydraulic mast jack.

4 3Di 870 Inshore Main in 7 knots TWS Photo by Steve Benjamin The mainsail is 3Di 870 with dpi and one reef. The jibs are all 3Di 870 and go through the wind range - J1, J1.5, J2, J3 and J4 (ORC heavy weather jib). The J1 is a new 3Di technology and is extremely light and powerful. As the sail trials progressed we determined more camber was required in the head of the square top mainsail, and we fitted a softer gaff batten (top batten or batten 1 ) which made a big improvement.

5 Upwind in last race LVSB with Inshore Main and 3Di J1 Photo by CC Harding Photography

6 Testing the new 3Di J1 Photo by Steve Benjamin DECISION is a modern fast planing boat and great attention was paid to the offwind package as well. The bowsprit is especially long to move the asymmetrical tack as far away from the mainsail as possible, and make room for the staysails and jibs to fly under the asyms. The asym inventory consists of a Fractional Code Zero (Fr0), Masthead Code Zero (A0), A1, A2, A3 and A4. There is also a Spinnaker Staysail (SS) and Genoa Staysail (GS).

7 Inshore Main, A2, & SS photo Photo by CC Harding Photography

8 With high performance boats like the Carkeek HP 40 every maneuver has to be carefully contemplated because in true wind speeds above eight knots the crew weight is needed on the rail hiking and if the boat is turning, it is not moving at its maximum speed potential. Therefore a pedestal winch grinder was fitted aft, so that two grinders could be used to hoist and gybe the asymmetricals. The winch system has a drum below deck for the string drop. Essentially, the retriever cord attaches to a patch in the lower middle of the asymmetrical and runs below deck to the transom, and then to the drum. For the drop maneuver the retriever line is pre-tensioned, the sheet is blown, the halyard and tack line are blown, and the asymmetrical is sucked below deck by the two grinders. To help complete the package, North Graphics inked the custom DECISION graphics onto three of the asymmetrical spinnakers. Customizing the graphics for racing teams is one of the many things we do best at North Sails and the DECISION artwork is a prime example.

9 DECISION's gavel graphics on A2 Photo by CC Harding Photography

10 Now you may be wondering how DECISION performed at the IRR and LVSB. At the IRR we finished fifth in a competitive Caribbean Sailing Association (CSA) Class that was won by the Melges 24 BUDGET MARINE (with North Sails and helmed by well-known Italian offshore sailor Andrea Scarabelli who is also a North salesman). A podium finish was nearly assured, until the beginning of the last race when a starting line collision forced retirement for repairs. At the LVSB the second overall in Class was accented by winning the last race. Following DECISION will be two more Carkeek HP 40's - DENALI 2 for Bill McKinley based in Harbor Springs, MI and SPOOKIE for Heidi and Steve Benjamin based in Long Island Sound. For more information please see - Carkeek Design Partners ( High Performance Rule ( - website under construction) Les Voiles de St. Barth ( North Sails ( Rig Pro & Southern Spars ( St. Thomas Rolex Regatta (