irc IRC: 1.020 (provisional) Class IRC applied for.
Portsmouth Yardstick:
UK: 894
US: 70.4
phrf PHRF-NB: 105
I: 21ft 11 3/4″ (6.7m)
J:  7ft 5 3/4″ (2.28m)
P:  25ft 7 1/2″ (7.81m)
E:  10ft 3/4″ (3.07m)
LOA:  21ft 1″ (6.40m)
Disp:  749lb (340kg)
Draft:  4’6″ (1.37m)

US PHRF Sportboat Comparison Matrix

See how the Viper 640 stacks up:  regional sportboat PHRF ratings


From time to time new breeds of race boats appear on the racing scene. They often cause organisational problems for clubs and sometimes upset the results pecking orders. One example was the J24 which was introduced into a market dominated by IOR designs. Race organisers had to adapt their fleets to cope with this tippy 24 footer which was as fast as their 34 footers.

Well, it has happened again. The new breed of race boat known as the Sportsboat, although welcomed by those who sail them, has caused problems for race organisers. They just don¹t fit into the existing rating schemes. Some, like the Melges 24, have sufficient numbers to enable their major events to be run as class racing without the need for handicaps. However, from time to time individual boats will wish to race in handicap fleets and will need a handicap or rating.

Neither of the current schemes (Portsmouth Yardstick System and IRC) satisfies sportsboats. The answer, a combination of the two schemes, the RYA/RORC Sportsboat Rule (SBR) is exactly what has been jointly agreed by the RORC and the RYA.

The RYA will issue standard TCSs for class boats. This will be undertaken with TCSs being issued to classes where there are sufficient numbers of the boats racing, and the class association can convince the RYA that its class rules and measurement control is satisfactory. Classes falling into this category will be known as Recognised One-Designs (RODs). Any yacht of a ROD class, holding (and in compliance with!) the necessary One-Design certificate will be entitled to race in a sportsboat fleet using the new rule without applying individually for a certificate. The class association must of course first have applied for and been granted ROD status. At present only the Hunter 707 and the Melges 24 have ROD status.

For designs of which only a single example or a few boats have been built or when variations in design, weight etc. mean that a ROD TCS cannot be issued, the RORC issues individual certificates on the basis of physical dimensional data in a similar manner to the way it currently issues IRC ratings. The difference between this and IRC is that the algorithms used and measurements taken have been specifically designed to suit sportsboats, with the TCS itself being compatible with the ROD TCSs issued by the RYA.

For those familiar with an IRC certificate, it is worth noting that displacement/length ratio (DLR) is calculated slightly differently. Firstly, LWP in the SBR is taken to the aft end of the boat, irrespective of rudder and stern configuration. The effect of this is that the rated LWP of a sportsboat will often be longer than its IRC equivalent. Additionally, empty weight rather than sailing displacement is used for the other half of the equation. The net effect of these is that, for example, a DLR figure of 100 is equivalent in IRC terms to a figure of around 135.

The sail area/displacement ratio is a standard naval architectural parameter. Basically, the higher the number, the more generously canvassed the yacht. Typical IRC figures are in the region of 0.4 to 0.5 with such modern designs as the Mumm 36 at 0.58. At the other end of the scale, a Melges 24 sits on 0.88, ie on a comparable basis 50% more sail than the Mumm!

One point to make absolutely clear: The SBR IS NOT COMPATIBLE WITH IRC. It is an entirely separate rule. Any sportsboat wishing to sail in an IRC race must therefore apply in the usual way for her certificate. There is nothing to prevent a sportsboat holding both an IRC and an SBR certificate. Many will want or need to depending on the type of racing in their area. The RORC have recognised this and will allow 50% discounts on application fees to yachts applying for SBR certificates which already hold IRC certificates and vice versa.