ORC rules change: what about the boats?

The 2015 ORC regulations brought significant changes: specifically, the introduction of a new system for dividing classes, CDL (Class Division Lenght), was a game changer. With the help of one of the foremost experts on optimizing boats for ORC rating, Maurizio Cossutti, designer of many winning boats, we tried to understand the new margins of action to make your boat perform better in racing.

BEFORE YOU START: EVERYTHING YOU NEED TO KNOW ABOUT CDL

AT THE END OF THE DAY, DEAR OLD IOR…
“The CDL formula, which does not go into the merits of fees because it only serves to divide boats into classes,” Cossutti explains, “is based on the vessel’s tonnage length (i.e., hull length plus any corrections), which is coupled with its average upwind speed in 12-knot winds. It is a formula that is very insensitive to changes in boat weight and sail plan, so theoretically, it should limit the phenomenon of large boats decreasing even a small amount of sail area and finding themselves racing in the lower class with obvious advantages“. This was often the case with the system based only on GPH (General Purpose Handicap). “We went back to the concept behind the IOR tonnage.”

WHAT DOES IT CHANGE IN CONCRETE TERMS?
“The choice of upwind speed in medium winds as a key parameter,” Cossutti continues, “leaves a lot of freedom for shipowners on the choice of aft sails. The spi will be able to be larger, with obvious advantages from the point of view of performance at the carriers. It will be up to the owner to figure out the right balance between increased performance in actual and increased handicap in offset resulting from the larger sail area“. Regarding any changes to the hull “the stiffness of the CDL allows very little room for maneuver. I believe it is not worthwhile to adopt expedients (which might have made sense until last year) such as reducing fin weight to decrease the stability of the boat (and thus its speed), because the game is not worth the candle: the loss of performance would outweigh the gain from entering a smaller class“. Having to design a new boat, not much will change: “It will be necessary to work on volume distribution so as to minimize tonnage length. If a leaning boat was favored by tonnage before, it will not be favored now“. The importance of crew weight also comes out much scaled down: “Reducing crew members gains very little in terms of tonnage length: we are talking about one, at most two inches less. Ask yourself whether it is worth racing with four when there could be eight of you, especially from the point of view of ease of maneuvering“.

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THE OTHER (NECESSARY) ADJUSTMENTS
The new ORC regulations have undergone other minor adjustments, such as in the aerodynamics of jibs and Code Zero type sails and in the calculation of implied wind (i.e., the theoretical wind determined on the time taken by the boat to complete the course and the speed indicated by its polar curves), “in the past tended to disfavor smaller hulls. Now we will see. If you want to optimize your boat, you will now be freer to play on its performance in real“. The philosophy of the designer devoted to ORC, Cossutti concludes, will not undergo substantial changes: “You have to start with the strengths and weaknesses of the boat. Try to minimize the latter without going to the former“.

SO, ASK YOURSELF, IS THE GAME WORTH THE CANDLE?
In three points, we explain what to do (and not to do) to optimize your boat in ORC with the advent of Class Division Lenght:

1.
Since the CDL is based on the average speed of the upwind boat, you will have a free field as far as load-bearing sails are concerned: it will no longer be of any use to reduce their surface area to fit into a lower class. You will pay for the larger size in terms of fees, but it may suit you in terms of real boat speed (e.g., for easier glide).

2.
Low CDL variability allows little room for maneuver: it may not be worthwhile, for example, to reduce bulb weight to decrease boat stability. The loss of performance may be such that it may not justify the benefits of entering a smaller class.

3.
Think twice before reducing crew weight by leaving someone ashore: very little is gained in terms of tonnage length (1-2 cm) at the expense of crew efficiency in maneuvering. With the new CDL, the benefits of being few on board are minimal.

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