Please select your home edition
Edition
Naiad

Interview with Mike Urwin, Chairman of the IRC Technical Committee

by IRC / Louay Habib on 27 Mar 2012
© .
Mike Urwin, joint Chairman of the IRC Technical Committee, is interviewed by Louay Habib on some detail technical aspects of IRC.

LH: One objective of IRC is to provide a rating that will allow the existing fleet to be competitive while not being a disincentive to development - a delicate balancing act and one that is more important than ever in the current environment. Would you like to comment on the 2012 rating changes designed to change the balance between boats with non overlapping headsails and designs with overlapping headsails?

MU: Recent years have seen a steady trend towards new designs having non-overlapping headsails. This, and the trend among some boats originally designed with overlapping headsails to convert to a non-overlapping configuration, has prompted sail designers to develop improved designs for these sails in lighter airs. Allied with the fact that modern sailcloth is better able to deal with the higher loads in tall, high aspect ratio sails, this has changed the balance slightly in favour of the non overlappers.

The changes this year are twofold. We have firstly taken a fresh look at the efficiency of different styles of headsail going back to fundamental physics and recognising also the sail design and cloth improvements. As a result, we have made some detail changes in this area. Secondly, historically, IRC has taken no account of leech hollow meaning that any boat with a hollow leech headsail (sailmakers want to build hollow in to improve sail longevity and to minimise leech curl and ‘motoring’) was paying a small amount for area that they did not have. Reviewing this, we could see no reason not to properly account for leech hollow.

LH: There is always a question with new sails regarding size versus the rating and getting the balance right for a particular boat. What kind of help and information can be obtained from the rating office, e.g. Trial certificates.

MU: A trial certificate tells an owner/designer/sailmaker what the TCC would be for the proposed change. It is then up to the owner/designer/sailmaker to decide in the particular circumstances of that boat and the racing that she does whether the change is worthwhile. We do not and cannot give consultancy in this respect.

But (without giving away secrets!) the sort of questions that owners might perhaps be asking themselves are related to in what wind speed do we change down/reef? Is my crew generally underweight? Do we do lots of reaching? Do we race in predominantly light/heavy airs? Are we more competitve in light/heavy airs? Upwind? Downwind? What sort of courses do we do? All windward/leeward? Passage races? Etc, etc.

Answering those, and all the other issues, then helps in deciding how to configure the boat.

LH: How does IRC treat spinnaker pole length? And what about ‘prods’ shorter than STL?

MU: In the good old days, boats could have spinnaker poles to a maximum in length of J. 1mm longer incurred huge rating penalties. That has not been the case under IRC for as long as I can remember. Firstly, STL (Spinnaker Tack Length – the length of the longest pole or bowsprit or tack point on the deck) is linked to spinnaker area, not J. Secondly, if the pole is a little longer, or a little shorter, the TCC will be a little higher or lower. This then allows the owner/designer to vary (within reason....!) STL to suit the actual boat and her sail wardrobe rather than be constrained by the somewhat artificial J.

IRC does not care about boats with short (ie shorter than the spinnaker pole when measured from the mast face) prods. Provided that the boat is rated for a spinnaker pole, she can also have a centreline bowsprit no longer than the rated STL without rating increase. If the prod is longer, then its length from the face of the mast becomes STL.

LH: What, if any, special circumstances affect the rating of yachts set up for two-handed sailing? What if I race my boat two-handed and fully crewed, can I have two certs?

MU: IRC Rule 9.2.1 addresses short handed certificates. This is clear firstly that a shorthanded certificate is only valid for shorthanded races and secondly that only the data listed in that Rule can be varied from that on the normal (primary) certificate.

IRC TCC for shorthanded certificates is calculated in exactly the same way as for normal ceriticates. So, the only point of a shorthanded certificate is to allow a boat to hold two IRC certificates in different configurations, one for fully crewed racing and the other for short handed racing, avoiding the necessity (and cost) of continually amending and re-amending the certificate. The corollary to this is that a boat that is only ever raced short handed does not need to hold a shorthanded certificate.

LH: How is it possible for Hull Factor to change either during a year or from year to year?

MU: Except in the rare case of an error here, or clarification of detail by a boat, HF will only change during a year if the boat is modified. That may be any physical change: a new or modified keel, re-ballasting, a new/modified rudder, or removal/addition of fitout. This latter is addressed here.

The asessment of HF is continually reviewed to firstly improve our assessment methods and secondly to incorporate novel developments in the design and construction of boats. Any changes to our methods are incorporated at the beginning of the next certificate year. So, an HF change from one year to the next without any change to the boat is most likely to be due to a detail change or changes to the methodology that the rating offices use to assess HF.

LH: RORC races typically announce class splits well before the event, however some regattas do not, which means that competitors have little idea of which class they will be in and who they will be racing against. Does the rating office have any guidelines to remedy this or are there plans to address the problem at IRC events?

MU: No! This is a matter for event Organising Authorities, not us. Although we are always happy to advise Oas.
This is always difficult for events. For long standing regular events particularly those such as the RORC Series which runs over the course of the whole season, the pattern of entries will be well established allowing class breaks to be pre-determined. For events where the number and type of entries may well vary significantly from event to event, the organisers need to retain the flexibility to set class breaks based on actual entries. If the class breaks are set in stone months before an event, very uneven class numbers are often the inevitable result.

LH: What are the advantages of getting an endorsed IRC certificate?

MU: The disadvantage is that it will cost a little more in terms of both cost and effort. So, if you just want to get racing, don’t bother! Get the boat (and the crew.....!) up to speed first.

Once you are up to speed, having the boat weighed and measured for Endorsement is likely (but not guaranteed!) to result in a small decrease in TCC because of the rating office’s conservative approach to unproven data. As an example of this, for unweighed production boats, we will use the weighed weight of the lightest example of the design. The likelihood is that your boat will be a little heavier. A similar policy is used in respect of unmeasured rig data.

The intangible benefit of an Endorsed certificate is the knowledge among you and your competitors that your TCC is correct. So, when you win, you can hold your head up high at the prizegiving.

LH: How does IRC prevent a boat with a ‘cosmetic’ carbon fibre interior rating the same as a boat with an identical interior but one built for everyday use?

MU: We weren’t born yesterday! We have numerous photographs of boats showing vases of flowers, bottles of wine, napkins, etc, etc on the boat’s saloon table. Which is in fact the engine box…..!

IRC application forms include questions about a boat’s fitout and also the materials used. If we are in any doubt, we invariably ask for greater detail by way of drawings, or preferably photographs.

We then have a standard methodology to asses this aspect of the boat. Work on this during the last couple of years has further improved our ability to detect the purely ‘cosmetic’ and to be confident that we are getting this right.

LH: Thanks Mike. There are many more questions I could ask. But that’s enough for now.

Note: IRC is jointly owned by RORC and UNCL. Mike Urwin (RORC) and Jean Sans (UNCL) are joint Chairmen of the IRC Technical Committee.
North Technology - Southern SparsInSunSport - NZBarz Optics - Floaters

Related Articles

CYCA Land Rover Gold Coast Race - Start video from Boatsontv
Geoff Waller of Boatsontv was on the water to capture the start of the CYCA land Rover Gold Coast Race Geoff Waller of Boatsontv was on the water to capture the start of the CYCA land Rover Gold Coast Race, which is used as a feeder for the race fleets to the popular Queensland winter regattas such as Hamilton Island Race Week. He also talks with Scallywag skipper David Witt a few days before the start of the winter classic.
Posted today at 12:17 pm
South Australians early casualties of Land Rover Sydney GC Yacht Race
The two entries representing South Australia in the 2016 Land Rover Sydney Gold Coast Yacht Race became early casualties The two entries representing South Australia in the 2016 Land Rover Sydney Gold Coast Yacht Race became early casualties after both sustained bow damage in separate incidents, joining a NSW yacht that was involved in one of those incidents, all three within the first half hour of the race.
Posted today at 9:20 am
LMAX Exchange wins the Clipper 2015-16 Round the World Yacht Race
LMAX Exchange was confirmed last night as winner of Clipper 2015-16 Round the World Yacht Race. LMAX Exchange, skippered by Frenchman Olivier Cardin, was confirmed last night as winner of the tenth edition of the world’s longest ocean race, the Clipper 2015-16 Round the World Yacht Race.
Posted today at 9:03 am
CYCA Land Rover Gold Coast Race - Images of supermaxi Scallywag
Sydney photographer Michael Chittenden filed this gallery of images from the start. The supermaxi Scallywag made her ocean racing debut in the CYCA Land Rover Gold Coast Race which got underway on Sydney harbour on Saturday afternoon. After a tight start the David Witt skippered supermaxi settled into her work and began the chase with her long standing rival, Wild Oats XI.
Posted today at 7:19 am
Edgartown Race Week - Final
It was a rainy and dreary start to the day out here on Marth’s Vineyard. The racing started at 11:00. It was a rainy and dreary start to the day out here on Marth’s Vineyard. By 11:00, it became a blustery and rainy day. The racing started at 11:00 and I haven’t sailed in that much rain in a while.
Posted today at 6:20 am
Nic Douglass - On the dock and on board with the 'fat bottomed girl'
Nic Douglass, caught up with the crew of the supermaxi, Comanche, after she had completed her latest mission Adventures of a Sailor Girl, Nic Douglass, caught up with the crew of the supermaxi, Comanche, after she had completed her latest mission and had chopped 27.5hrs off the trans-Atlantic Race Record for a manually powered monohull. The last time I was waiting for Comanche to arrive after achieving a goal that they had set out to achieve was a very different scene
Posted today at 5:25 am
CYCA Land Rover Gold Coast Race - Replay coverage of the start
Replay coverage of the CYCA Land Rover Sydney Gold Coast Race start Replay coverage of the CYCA Land Rover Sydney Gold Coast Race start. The fleet got away to a clean start this afternoon in Sydney. The supermaxi, Wild Oats XI (Oatley family) led the 177 strong fleet through Sydney Heads, with ScallywagHK, the former Ragamuffin 100 in second place. Commentary bought to you by Bob Killick and Warwick Rooklyn.
Posted today at 4:33 am
SAP Extreme Sailing Team and Alinghi apply the pressure in Hamburg
Morgan Larson’s dominant Omani team who go into the clubhouse in first place at the half way stage of the Act. 2016 Extreme Sailing Series™ - A sunny day on the River Elbe coupled with a lively breeze saw SAP Extreme Sailing Team and Alinghi challenge Oman Air for honours on the second day of the Extreme Sailing Series™ in Hamburg, but it’s Morgan Larson’s dominant Omani team who go into the clubhouse in first place at the half way stage of the Act.
Posted today at 2:55 am
Comanche sets new trans-Atlantic Record - Video of the Finish
High definition video of Comanche crossing the virtual finish line off the Lizard to set a new monohull trans-Atlantic r High definition video of Jim Clark and Kristy Hinze-Clark’s supermaxi, Comanche setting a new, provisional world record for crossing the Atlantic for a monohull, in a manually powered sailing vessel of 5 days, 14 hours, 21 minutes 25 seconds. The video was recorded on and off the boat as she crossed the virtual finish line off the Lizard, southern England.
Posted today at 1:06 am
Close fight around Wight on Day 6 of Brewin Dolphin Commodores' Cup
20-25 knot winds and glorious sunshine made for one of the most memorable races around the Isle of Wight on record With a win for Eric de Turkheim's A13, Teasing Machine (despite destroying a kite), and a second for Daniel Andrieu's Sun Fast 3200, Cifraline 4, France Blue have leapt ahead in the overall results, now holding a 35.5 lead margin over the second placed Flanders North Sea Team.
Posted on 29 Jul