IRC inför 2010

Intervju med Mike Urwin, RORC Rating office. Små förändringar inför nästa år, men bra att man nu skall använda redskapsreglerna fullt ut.

What is IRC’s underlying philosophy?
We want IRC to be a permissive rule. IRC Rules say it is for ballasted monohull keel boats with not more than two masts; those are the only fundamental restrictions we want to apply. So, if someone comes along with something novel, like water ballast or canting keels or asymmetric spinnakers, or bowsprits… we want to embrace that but until we get to understand what the new idea is all about, we try as hard as possible to be cautious in the way we rate the boats. If we don’t know what the effect will be on the performance of the boat, we tend to over compensate. Do we always get that right? No. Do we then do something about it? Yes.

How in practice is IRC managed?
IRC does not rate individual boats, it rates the features of boats in general. We are not looking at individual boats but the whole fleet. So, as and when necessary, we make changes to the rule on an annual basis, it is very, very rare that we will make changes during the middle of a season. We run a research agenda and at the end of each year the IRC Technical Committee decides which things we want to change, which things need more work and which things are to be left alone, as they are perfectly alright. These changes all happen on a yearly basis; January 1st in the Northern Hemisphere, June 1st in the Southern Hemisphere.

We also look at what is going on, out there on the water, especially particular styles of boats that are doing well. At the recent UK IRC owners meeting, there was noticeable comment, from around the country that boats with bowsprits were doing perhaps rather too well. That fits with our own observation, so the likelihood is that there will be a small tweak to that next year.

There has also been a fair amount of ‘noise’ about the King 40 in America, Soozal, which has a powered winch package. I don’t think it is appropriate for a boat of that size to have high speed powered winches and others seem to agree with me and there will be a change in how IRC deals with that next year. We want to be permissive but we don’t want people to think they have to go out and fit powered winches if they are going to win a regatta, IRC does not encourage unnecessary expense. If a development comes along with value to the sailing community, we will not penalize it. If the development has little or no value than we will not look as favourably on that.

Powered winches are a great example; if the boat we are rating is over 100ft then everything is powered, if a boat of 50 ft is primarily used for cruising and has a powered main sheet winch, we don’t want to exclude those boats from IRC. We have to cut the maths differently for boats of various sizes and uses.

Powered winches on 40ft boats are rare today but we don’t want it to become de rigueur. The same goes for any other source of stored power, it will be treated in the same way.

What about Endorsed certificates?
We have no general opinion as to whether or not an IRC event should insist on endorsed certificates, it is up to the each organizing authority to decide. If asked, we will advise them but at the end of the day it is their decision. We would ask who the event is aimed at: If it is aimed at club racers there is little point in insisting on endorsed certificates; if the event is aimed at an international fleet of high performance yachts, such as a Mini Maxi regatta then perhaps there is a valid argument for entries having endorsed certificates.

What is interesting to note is that it is rare for a yacht to see any significant increase in its rating after its certificate is endorsed. It is much more common that a rating goes down. The boat is likely to be a bit heavier than thought and the sails a little bit smaller.

What about consistency of ratings? Do these differ from place to place and country to country?
The rating for a production boat can not differ from place to place or country to country unless the data for the boats is different. We have standard files for absolutely strict one-designs, but production yachts can and do vary significantly: the hulls may be the same but there are enormous variations in rigs, sails, keels and weight. The length and beam may be the same but we will need the individual rig and sail data for that boat. Building boats is a hand-crafted process, as a result of which variations are inevitable, and owners themselves contribute to variations in weight by specifying different fitout. All this means that a typical 40 foot production cruiser can vary as much as a tonne in weight from a sistership.

What about box rules? How do they fit within IRC?
IRC is a rating rule which applies a time on time handicap but there is no reason why we would not produce a box rule, if we were asked to do so by a group of owners. There is nothing wrong with a box rule, RORC have administered the Whitbread/Volvo 60 and Volvo 70 Box Rule. However, they do not suit owners who are club racing, primarily because the boats have multiple purposes. However, if a group of owners wanted us to develop and administer a box rule we would be more than happy to discuss that.

How do you police rule compliance?
A good example to use is stacking (ie moving all the gear to one side of the boat to increase righting moment). Under the racing rules of sailing (Rule 51) stacking is illegal and we support that. It is however permitted in IMOCA 60 Class racing and the Volvo Ocean Race, but the sailors hate it. The problem is policing it; inshore courses are probably too short to gain an advantage and boats are in sight of each other but offshore is a different matter. So we have to rely on the integrity of sailors which is no different from other areas of the sport, like going around a mark. In reality, there are much more efficient ways of cheating than stacking. The philosophy of RORC Rating is to continue to instill an ethos of competing within the rules of sailing.

2010. What changes can owners and sailors expect to see?
There will be many small changes next year, potentially issues such as bowsprits, and stored power. We will also be slightly refining the way we treat keels. One significant change to the rule is the way it will look. From the 1st January 2010, we will be adopting the Equipment Rules of Sailing, in their entirety. We are doing that because IRC is an international rule and we need to have measurements and standards that are common to all countries. We want to have measurers who have been trained by us or the relevant National Authority. We want to have consistency of training and measurement, throughout the world. In practice, this won’t actually change anything but it will result in improved IRC measurement standards around the world.

For a more information about IRC including frequently asked questions:


  1. Nobbe Oct 9, 2009 Reply

    Hur funkar IRC, justeras talen om en båt skattas felaktigt av nån anledning? Finns det nåt liknande som i SRS/LYS?

  2. Patrick L Oct 9, 2009 Reply

    Nej, IRC är inte en empirisk handicapregel utan en ratingregel. Man försöker vara tydliga med att man inte skattar enskilda båtar utan egenskaper hos en fleet av båtar.

    Men om flera båtar med liknande egenskaper får uppenbart felaktiga mätetal kan man väl gissa att RORC tar sig en titt på formelns subjektiva delar, för sådana finns. Så skedde väl med canters för några år sedan när de i stort sett var omöjliga att slå i IRC. Numera har jag förstått att det inte så längre utan canters har successivt fått högre mätetal. Men det är hörsägen, jag har inte kollat själv. Jag kan gissa att PelleL eller någon annan med koll på IRC vet bättre.

  3. MiniMe Oct 9, 2009 Reply

    Nja, Patrik det är väl en sanning med modifikation. Det finns en del subjektiva inslag i IRC t.ex. rigg factor, hull factor, bedömning av kölform mm. Visst är IRC en mätregel men med viss empiriskt inslag. Rating är väl allt som inte är entyp eller box-regel/scratch???

    jag vet dock ej om man gör en omvärdering om man ha klassas fel åt något håll.

  4. Patrick L Oct 9, 2009 Reply

    Nu blev det många frågor på en gång. IRC är väl inte en ren mätregel utan en ratingregel? Jag skrev också att det finns subjektiva inslag i själva formeln, till skillnad från t.ex. i ORCi.

    MEN: Om jag har fattat det rätt så uppger i alla fall RORC själva att de inte skattar enskilda individer utan egenskaper i en fleet. Om det stämmer i verkligheten eller ej är jag inte man att avgöra. Men jag tror inte att de kör en enskild båt, får ut ett mätetal och tänker “det var lite lågt, vi skruvar lite på HF”.

    Men däremot tror jag att om man generellt märker att en viss egenskap över- eller underskattas så ändrar man det – men i så fall för alla båtar som har denna egenskap i en fleet, inte bara för en individ:

    “IRC is a ‘live’ rule. By this we mean that the maths behind the calculation of TCC is continually adjusted on an annual basis to reflect changes in design, sailing practice, etc. The changes affect generic types and characteristics, not individual boats or designs.”

  5. PelleL Oct 9, 2009 Reply

    Det är ju som Patrik säger att IRC är en levande men hemlig regel. Det är nog så att det finns två personer som har full insyn i hur regeln funkar. Det empiriska eller subjektiva inslaget är litet och man säger själva att man använder en objektiv metod för att bestämma de subjektiva faktorerna…..sic..strukturen i matematiken är förmodligen samma som många regler haft sedan hedenhös nämligen att TCF=konstant*sqrt(mätt Längd*sqrt(segelyta)/depl^1/3)*ett antal korrektionsfaktorer

  6. MiniMe Oct 9, 2009 Reply

    Ja, det är just korrektionsfaktorerna. Sen kan man spekulera hur pass stor inverkan har de subjektiva inslagen. Som Pelle säger så är regeln hemlig. Hur som helst skulle de inte finnas om det skulle vara betydelselösa…. ;-)

  7. Author
    Peter Gustafsson Oct 9, 2009 Reply

    HULL FACTOR; The IRC Thermometer!

    Man kan ju kalla dem “subjektiva” men det verkar vara en ganska “objektiv” checklista som ger dessa värden. Finns en bra korrelation mellan olika båttyper och de ger inte uddabåtar med konstiga mätetal. Sedan påverkas såklart hela flottan, men det känns bättre än att folk gissar utifrån en inskickad spec :-)

    And putting the whole thing into context, ultimately within the sensible range for a particular concept of boat, the effect of HF on TCC is small, generally less than 0.005.

    Här är några av de svenska båtarnas HF.

    ASPECT 40 10,8
    HAPPY 10,8
    NEED SPEED 6 10,6
    GOOSE II 10,5
    ILDERIM 10,3
    FARR AHEAD 10,2
    KRUT 8,7
    WAIT AND SEE 8,7
    BLUR 8,6
    ELLVANN 8,4
    DEHLTA 8,4
    MATRISEN 8,3

    • MiniMe Oct 10, 2009 Reply

      är det bra eller dåligt???

      Jag tycker att ett empirisk eller subjektivt inslag kan vara bra och förenklar. Som Mike Urwin & Jean Sans själv säger så har de ingen kunskap om skrovformen av akruell båt i IRC utan där kommer kompensation i bilden. De säger okså att normalt är inverkan mindre än 0,005 men jämöfrelse mellan båtar som passar in i mallen är det sällan problem med.

      Intressant är att de svenska båtar inte skiljer så mycket i hullfactor. Kan man tolkar att hullfaktor sträcker sig från 3,2 för värsta cruiser till 14 för extrem racer? Så är det väll alla cruiser/racer med kanske viss tendens mot racer.

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