Difference between IRC and IMS

dunno about the technicalities (still bouncing around my brain they'll be here in about a day) but IMS is making some coyote ugly boats. I race PHRF and it seems to be ok, there's a couple of ratings needing adjustment but not by much.

 

All the measurement rules so far have produced ways to manipulate them and in general until you can measure all variables any rule will continue to provide that ability.

As for IRC my only concern with it is that in the US the people who are most vocal about moving to it to get out of PHRF are advocating for it for all the wrong reasons. IRC is just like PHRF and has the same limitations as PHRF. IRC is not a panacea and many of the people who think they are getting ripped off with their PHRF rating and not winning will be very disappointed when they find themselves still not winning under IRC. IRC will not make you a better sailor. The people who think they are going to get a better rating or someone else is going to get punished in their rating will soon become bitter enemies of IRC and we will find ourselves facing the same problem again.

IRC may be better than PHRF or may not be. ONe thing for sure it will not make you a better sailor and if you are looking to rating to help you win you probably will not like IRC anymore than PHRF, right now the grass is greener.

 

They are voluntary groups dominated by a particular groups preferences. Take out the variety and none of you would race under the boring, same old boats, rules. Variety causes conflict, that's what drew you into these associations. Right. Otherwise,everybody into the 60' Sunfishes.

 

Re "Here in France we practice IRC (ex CHS) since 1985, I could affirm you there is nothing inside IRC. it is only based on 2 subjective Coefficients (Hull factor ang rig factor) a large amount of Age alowance. And please stop to read Seahorse Mag to get info on handicap system it is not an objective way to lean about IRC or IMS !!!!!

A sorry I miss one factor for IRC ....politics....."

Well, I don't read Seahorse to get info on handicap systems. I sailed with an ORC councillor who supports IMS, rang up Frietrich Judel (who helps run the technical section of the IMS), spoke to Marcelino Bottin of B & C, Russ Bowler and Jim Schmicker from Farr, Jim Pugh from R & P, the Aussie IRC co-ordinator, Mike Unwin who runs RORC's rating office, emailed Jen his offsider, interviewed Mark Mills, John Corby and many other people.

NONE of them has ever said that IRC is totally subjective. As Jen from RORC said on another forum when the claim for any subjective result came up...."Where do people get this crap from? (mad.gif). The rating is what the formula calculates it as."

So there's the person who punches in the numbers saying that the formula calculates the rating.

Paul, re IRC, your boat and FP. Maybe any boat that extreme will under almost any rule, because there seem to be so many diminishing returns in such a boat.
I don't know how your boat will rate under IRC; the Thompson 8 doesn't rate too well but is mid-fleet on CT I think.. But how accurately can PHRF rate it?? Where can they start getting info that's better than the info from IRC?

If IOR was more accurate than IRC, why did ULDBs etc perform badly on IOR?

Re the IRC specials from BBH and S-H. The won that won the S-H lost the AC to a R/P canter, and the owner has won IRC overall (IIRC) and in class in the S-H with his previous Swan. I think he also won the Sydney 38 OD nationals froma fleet of 29 boats or something. So a S-H win to such a good campaigner seems fine to me.

Re "This thing not occour under the IRC rule. No displacement measurement are done, and every owner must input the boat's displacement..."

Not here, every IRC boat in Australia must be measured. I know, I repeatedly check with John Anderson at the YA NSW rating office 'cause I don't want to pay for my boat to be weighed and I think it should be OK for older boats to go off catalogue figures for local racing. It's not allowed here. All IRC boats must be weighed or use OD or IMS figures. How did the Skandia mess happen? Dunno. Similar (actually, worse) problems occurred under IOR and other rules.

I understand the appeal of IMS, I understand the appeal of PHRF, I'm just trying to defend IRC against attacks that don't accord with how I see it (not that I' m necesarily right, of course).

 

Influence of factors on IRC rating

There seems to be some experts on the IRC rule on the forum
can anyone tell me approximately how any or all of following modifications are likely to effect my TTC on a jeanneau sunshine36 LOA 10.7 m TTC 0.94
-Large increase of stern overhang by 1.2 m
-folding propellor
-oversized spinnaker 14.90x8.25 metres instead of 14.06x8.06
thanks

 

IRC modification

Hi,
the IRC rating formulae is secret and there is a "Subjective Factor" so that not only measurement data are taken into consideration during the rating process.....(another bad thing...).
Anyway, the best for you is to work on the boat overhangs as as much you measure overhangs as less the LWL will be rated, as slow your boat will be rated.

My suggestion is to work on the fore overhangs as I've noted that has more influence on the rating calculation.

To increase your spinnaker will have a bad reflection on the TCC, but I think that you have to work not only around the TCC but also on the real performances of your boat, so if she need more sail area downwing, do not care on the TCC and sail faster...

alex.

 

Hallo everybody,

In my opinion ims is the best ruel ever cause its the most accurat ruel.
The Vpp works really good and its the only way to go if you have completely different yachts with a large variaty of ages.
I just talked to Mr Judel from Judel & Vrojilk yacht design
and he explaind to me that not the rule is the problem
the problem are the race courses
the yachts are not optimised to the rule they are optimised for up and down
if they would have to sail the old olympic course with a reaching leg they would look different thats why you can winn an offshore race with a TP 52 under IMS
the IMS boats are optimised for up and down the tp 52 is an better alround design which goes fast an a reaching led which you have quite often in offshore racing

don't change IMS change the race course and you will see that IMS is much more accurat then IRM IRC
the currrent rule changes even favorit older boats

cheers konstantin

 

I may not have expressed myself clearly
I am not planning to make these changes, they had been made to the boat I bought except for the folding prop I installed (i.e. spinnaker coming from another model, and large extension on the stern)
If I measure the boat and apply for a certificate and think the TCC is unreasonably high I would like to know where the penalties are coming from
Does anyone know the penalty for folding prop ?
and for increase in spinnaker of 8% ?

 

All handicap attempts are bogus. The dynamics of the race course makes it so; it is not a stationary environment. Boats of different speeds sail in different conditions, especially on longer courses.

Race one-design, if you want to find out where you stand as a sailor. Race handicap if you can spend more money than your competition.