Are you tired of reading about IMS boats yet? I hope not. We should all be interested in development classes that give designers the opportunities to increase performance. So far, the IMS has had its problems, but boat speed has not been one of them. I have not yet talked to a sailor who has raced on a new IMS boat who did not rave about boat speed relative to older designs. This is exciting.
The new C&C 45R, designed by Bill Tripp, is a perfect example of this type of yacht and shows clearly the direction the IMS type is heading. On the surface, it looks like we are witnessing a pure horsepower race, but there is more to it than that. We have found that the IMS hulls are forgiving when pressed hard and, therefore, can get away with a bigger rig. Stability is increasing with bulbish-type keels and deep draft enhanced by high-tech construction resulting in larger ballast-to-displacement ratios. This, too, allows the rig to go up. True, it is a horsepower race, but a race made possible by a general improvement in the basic format of the rule.
Note that this design breaks with the tradition of all C&Cs being in-house design projects. With one of the Cs (Cassian) working in that big design office in the sky, and the other (Cuthbertson) long retired, we've seen the design chores at C&C ably handled by Rob Ball. Rob is now with Concordia Yachts. C&C went to Bill Tripp for this new design. Bill has had considerable success with the IMS rule and was a natural for this effort.
While the origin of the new boat is a departure for C&C, I think the intent of the new boat is very much in line with past efforts of C&C. The new boat will once again combine speed and beauty in three versions, ranging from an all-out racing model, the "R", to an "XL" model, meaning extra luxury and extra light, combining the high-tech racing materials and equipment of the R model with the best joinerwork. Rigs and keels can be modified to keep everyone happy.
This rig gives a SA/D ratio of 24.79 which, believe it or not, is quite tame for a new IMS boat, as we have seen this ratio exceed 28 recently. Note the long boom with the mainsheet traveler actually aft of the helm. I think two things are interesting about this E dimension. The first is that I don't think the boom could have been any longer without the roach of the main overlapping the backstay too much. Secondly, we have come to associate long booms with off-the-wind performance, but Tripp states, in his designer's comments, that the focus of this design is upwind speed. The IMS rule is quite sympathetic to the E dimension.
One of the things that strikes me in looking at this hull shape is that it is not too unlike the MORC shape that works best. The bow overhang has been reduced to almost nothing, and the long raked transom we saw with IOR boats is gone. Note the location of the rudder. Tripp has pushed the rudder forward to get into cleaner water where it won't be fighting with, and compounding, the quarter wave. Considering the lines are fair and clean, there is a lot of boat aft in this design. This keeps the pointy end real pointy to slice through the waves and puts the power aft where it can be used to keep the boat on her feet.
"Balanced ends" is a term that you hear cruising designers use, but it has always been a mystery to me. Both ends of the boat do very different jobs, and once your boat begins to move forward, all the arguments line up in favor of asymmetry in the ends. The D/L ratio of this design is 143. The general purpose IMS rating of this boat is 558.9 seconds per mile.
If we have spotted a weakness in this rule, it has to be the interiors, with interiors designed only to the letter of the rule and not the intent. C&C, while recognizing the critical weights question, has gone a step beyond the rule minimum interior. They have come up with a layout that, at the time of this printing, is still undergoing refinement, so we won't show you a drawing. Initial drawings show this layout to be a comfortable compromise aimed at true dual-purpose usage.
The hull uses C75K 200, a Kevlar hybrid, in conjunction with aircraft grade pre-impregnated balsa coring with vinylester resin. Stingers and frames of Kevlar hybrid construction reinforce the high stress areas.
I have been a fan of the C&C yard for years. Tripp has given us a design that should be very quick and wrapped it in an attractive look that should win new converts to both the IMS rule and C&C.
|Sail Area||1107 sq. ft.|
|Auxiliary||Yanmar 4JHE 44 hp|
This story originally appeared in Sailing Magazine, and is republished here by permission. Subscribe to Sailing.