sail-world.com
 
 
News Home Cruising Photo Gallery Video Gallery
Sail-World.com : Interview with Mike Urwin, Chairman of the IRC Technical Committee
Interview with Mike Urwin, Chairman of the IRC Technical Committee

©
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.


by IRC / Louay Habib

  

Click on the FB Like link to post this story to your FB wall

http://www.sail-world.com/index.cfm?nid=95324

1:54 AM Tue 27 Mar 2012GMT


Click here for printer friendly version
Click here to send us feedback or comments about this story.







News - USA and the World

















Aldo Alessio Regatta - Three days of tight racing by Erik Simonson, Pressure-Drop.US,










Sailing Champions League - which is Europe's best sailing club? by Dan Ibsen & the Sail-World team, Copenhagen


Weta fun at the Wine & Roses Regatta by Bruce Fleming, Santa Barbara
















J/111 World Championships - The Winner is Shmokin Joe! by Stuart Johnstone, Cowes, Isle of Wight












2014 Detroit Cup - Morvan wins by Dobbs Davis, Detroit










2014 IFDS World Championships - Sunday’s race images by Tim Wilkes
Shark World Championships underway in Toronto
Anna Tunnicliffe: Alinghi second o'all - Extreme Sailing Series, Day 3
Formula Kite World Championships - Nocher and Bridge crowned Champions
Emirates Team NZ: Frustrating Day 3 in Extreme Sailing Series, Cardiff
Extreme Sailing Series: Light winds help The Wave Muscat - Day 3
Extreme Sailing Series 2014 Act five - Absent without leave – the wind
IFDS Worlds 2014 - Images: Race day five
Herreshoff Classic Regatta 2014 - Images by Ingrid Abery
Youth Olympics - Gold to Argentinean and Chinese Techno 293 racers
Youth Olympics Games Nanjing - Double Youth Olympic Gold for Singapore
Sevenstar Round Britain and Ireland Race 2014 - Two Handers celebrate
Audi Melges 20 U.S. National Championship 2014 - Brazilian dance party
IFDS Disabled Sailing Worlds Day 5 - USA fighting for Rio 2016 Berths
J/111 World Championship 2014 - Day 4: Shmokin Joe consolidates lead
Anna Tunnicliffe: Alinghi on top - Extreme Sailing Series, Day 2
2014 IFDS World Championships - Breezy frustrations
2014 Detroit Cup - Down to the final four
Sevenstar Round Britain and Ireland Race - Every finisher's a winner
2014 49er, 49er FX, Nacra 17 U.S. National Championship - Day 2
J/24 US National Championship - Will Welles leaps into lead   
J/111 World Championships - Day 3   
Extreme Sailing Series Act 5 – Day 2   
Light wind and a freak storm at Youth Olympic Sailing Competition   
31st Audi Hamilton Island Race Week - Declared 'best ever'   
2014 IFDS World Championships - Aussies on fire   
2014 IFDS World Championships - Saturday’s racing images by Tim Wilkes   
2014 IFDS World Championships - Day 5 images by Jude Robertson   
2014 Audi Melges 20 U.S. National Champ - Day 3 images by Joy Dunigan   
Holt’s 25-year dream comes true with 505 Worlds Victor   
Emirates Team NZ: Collision puts an end to bid for a better day at ESS   
Extreme Sailing Series: Ben Ainslie Racing - mixed results on Day 2   
America's Cup: New brand and image partnership announced with SME   
Extreme Sailing: Tough and testing day on Cardiff Bay - Day 2 + Video   
2014 49er, 49er FX, Nacra 17 U.S. National Championship - Day 1   
2014 J/111 World Championship - Bigger breeze arrives on day 2!   
2014 Detroit Cup - Quarter-finalists determined   
2014 AWT Quatro Desert Showdown - Best Amatuer final ever!   
Audi Hamilton Island Race Week - Last day images by Andrea Francolini   
2014 Newport Bucket Regatta - Day 1 images by Ingrid Abery   


For this week's complete news stories select    Last 7 Days
   Search All News
For last month's complete news stories select    Last 30 Days
   Archive News







Sail-World.com  


















Switch Default Region to:

Social Media

Asia

Australia

Canada

Europe

New Zealand

United Kingdom


http://www.sail-world.com/event_images/image/Twitter_logo_small.png http://www.sail-world.com/event_images/image/FaceBook-icon.png  http://www.sail-world.com/event_images/image/RSS-Icon.png

United States

Cruising Northern

Cruising Southern

MarineBusiness World

PowerBoat World

FishingBoating World

 

Contact

Commercial

News

Search

Contact Us

Advertisers Information

Submit news/events

Search Stories/Text

Feedback

Advertisers Directory

Newsletter Archive

Photo Gallery

 

Banner Advertising Details

Newsletter Subscribe

Video Gallery

Policies

 

 

 

Privacy Policy

 

 


Cookie Policy

 

 



This site and its contents are © Copyright TetraMedia and/or the original author, photographer etc. All Rights Reserved.  Photographs are copyright by law.  If you wish to use or buy a photograph contact the photographer directly.
XLXL NEW US
LocalAds   DE  ES  FR  IT