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1/4 tonners + the cup

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Post Options Post Options   Quote Pabs Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 9:02am
Okay for some one who is not massivly experianced in yachting but is intrested in and the idea of the 1/4 tonners can some one give me an idiots guide to IRC/IOR what they are how they work etc
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Stefan Lloyd View Drop Down
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Post Options Post Options   Quote Stefan Lloyd Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 10:03am

IRC and IOR are/were measurement-based handicapping systems. There are around 8000 IRC certificates in issue worldwide and it's the main handicapping system in the UK for boats with beds. IOR was an alternative system that began in the 60s and died around the early 90s. Ton Cuppers were IOR boats built to a specific target IOR rating so they could race together without handicap - a concept somewhat like a development dinghy class. There has been a revival of the quarter-ton (around 26 foot) and half-ton (around 30 foot) classes for boats that previously had IOR ratings that made them eligible for those classes. However for reasons discussed elsewhere in this thread, they race today under IRC.  

 

Quarter tonners



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Post Options Post Options   Quote craiggo Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 10:24am
IOR and IRC are measurement based handicap schemes.

IOR was used extensively until the mid 80s but the current scheme used around the world is IRC.

IOR basically allowed you to calculate a length in ft which was then used to correct the boats elapsed time. From this several open classes formed ie, 1/4, 1/2 and 1 tonners. Basically these boats dont actually weigh 1/4, 1/2 or 1 ton but end up with an IOR length which is less than a given value for that class. From memory 1/4 ton IOR length was around 19ft by the mid 80s.

Unfortunately IOR created some strange designs, with hulls having large bumps to reach girth measurements and relying on lots of movable ballast, ie crew, to keep them going. The boats when measured had very low ballast ratio. Also the measurement was performed with the boat upright so large overhangs were used to gain waterline length when heeled. In the aftermath of the notorious Fastnet race, the IOR rule was heavily criticised for creating un-seaworthy boats, and some small mods to the rule were made during the 80s to try and sort this but the rule had already moved into decline.

IRC is the current measurement system in use, and I have to say I dont know exactly how the calcs are performed but it does seem to favour boats of a certain length. Ballast ratios seem high as do sail areas but I believe there has always been a 'fudge' factor applied by the ratings office which has often been the subject of much contriversy.

Anyway the re-born 1/4 ton cup is being run under IRC so many 1/4 tonners have been optimised with increased ballast (ie bulbed keels), fractional rigs with non overlapping headsails and larger spinnakers (area taken from the overlapping jibs).

The joy with any measurement based rule is that you can always optimise your boat to suit it, but it costs!!

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Post Options Post Options   Quote Stefan Lloyd Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 10:46am

Originally posted by craiggo

Basically these boats dont actually weigh 1/4, 1/2 or 1 ton but end up with an IOR length which is less than a given value for that class. From memory 1/4 ton IOR length was around 19m by the mid 80s. !

Eighteen feet in fact. The rating is just a number though: the boats were typically around 26 feet LOA.

 

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Post Options Post Options   Quote alstorer Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 11:34am
As I understand it, one of the differences with IRC is that the formula used is NOT public, and that it also also revised quite often. Part of the idea is that whilst designers can make good guesses as to what will rate "better" (ie essentially create a boat faster than those on the same calculated rating) they should not be able to know for sure. I think it also essentially gives bonuses to features which improve seaworthiness and onboard comfort?
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Post Options Post Options   Quote laser193713 Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 11:38am

The rule for IOR is actually under 18.5 ft not anything to do with metric!

The whole point in the IRC rule is that we dont know how it works, but through trial and error sail makers and designers have managed to work out a few general formulas, the important thing though is that it is not a performance based handicap.  Unfortunately there is a measurment called "hull factor" which is a measure of the racyness of a yacht, in quarter tonners this seems to change a lot and is known to be a fudge factor that they use to performance equalise the boats. The ratings office would not agree of course.

If anyone is confused, a performance based handicap is one like in golf, where the skill of the player is equalised by their handicap, a measurement based handicap would take measurements such as the height and weight of the golfer and the clubs they used and give them an expected handicap.  This would favour the better golfers of course which may be a good thing, but it is much harder to please everyone with a measurment based handicap system.  People spend a lot more money to get their boats right on a system like IRC than a performance based system like PY, so the sailing industry prefers measurement based systems.

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Post Options Post Options   Quote craiggo Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 11:48am
Originally posted by laser193713

The rule for IOR is actually under 18.5 ft not anything to do with metric!




Laser193713, I meant to write 19ft not m, so my previous post has been edited and is now correct.
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Post Options Post Options   Quote laser193713 Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 12:04pm
ok, i thought u meant it, i just wanted to clear that up, the metric system had hardly been heard of back then!
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Post Options Post Options   Quote Stefan Lloyd Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 12:32pm

Originally posted by laser193713

If anyone is confused, a performance based handicap is one like in golf, where the skill of the player is equalised by their handicap

In general in sailing performance based handicap doesn't mean that. It's meant to be a handicap for the boat, not the helm and crew. I say "in general" because some clubs do apply personal handicaps to some racing but that's different from what systems like PY and PHRF set out to do, which is to handicap the boat or class.

How the administrators of performance-based systems can actually differentiate between the performance of the boat and the skill of the crew for one-off boats is perhaps, like the manufacture of sausages, something best not looked into too closely.  



Edited by Stefan Lloyd
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Post Options Post Options   Quote laser193713 Quote  Post ReplyReply Direct Link To This Post Posted: 04 Sep 09 at 1:52pm

Dont let this forum make them sound boring! They're great boats to sail despite looking funny in some cases, we're glad our boat looks normal though!

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