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    Bulb Weight - Clarification

    IRC Bulb Weight refers to the Bulb as defined by the ISAF Equipment Rules of Sailing. This document is provided as clarification that all under-fin spacers and infills shall be included in the total Bulb Weight.

    The ERS defines Bulb as
    E.1.2(e) A hull appendage containing ballast at the bottom of another hull appendage primarily used to affect stability.

    Ballast is defined as
    C.6.3(e) Weight installed to influence the stability, flotation or total weight of the boat.

    E.1.1 defines Hull Appendage as
    Hull Appendage Any item of equipment – including the items listed in E.1.2– which is:
    • wholly or partly below the sheerline or its extension when fixed or when fully exposed if retractable,
    • attached to the hull shell or another hull appendage, and used to affect: stability, leeway, steerage, directional stability, motion damping, trim, displaced volume.

    And clarifies that:
    Any of the following shall be included in the hull appendage:
     corrector weights,
    • integral ballast, and
    • associated fittings.

    Therefore, all under-fin spacers and infills shall be included in the total Bulb Weight.

    Addition in reply to a specific question:
    Q. We have read the latest IRC bulb weight clarification were it clearly states that all under-fin spacers and infills shall be included, but we are not clear about the bolts/nuts/washers. Do you mind clarifying if we should consider these items as part of the weight?

    A. As any retaining bolts and attachments, as well as infills and adjustable weights, are only there as part of the bulb and would not be there if it was not for the existence of the bulb, these would be included in the bulb weight.


    Changes to 2017 Certificates

    Please note the following layout changes to the IRC certificate for 2017 (listed from the top of the certificate):


    • New certificate header – these have been updated to reflect our new IRC logo.
    • Aft rigging replaces Runners/Checktays in the Detail section
    • The validity stamps have been updated and your certificate will show either ‘Standard’ or ‘Rating Authority Endorsed’, see below.

    If you have not already done so, please read the 2017 Rules and Definitions which are online at - changes for 2017 are marked with a sidebar.


    Endorsement:  This is denoted by the ‘Rating Authority ENDORSED’ stamp at the bottom right of the certificate.   ‘Non-endorsed’ certificates are now known as Standard as shown on the stamp.  If you need Endorsement for an event you are entering, please contact your local IRC Rule Authority office as soon as possible for advice (details at the end of this document).


    Will I get a mast sticker?  NO.  With all IRC certificates now being emailed, after 28 years we have discontinued the IRC mast stickers.  


     Validity dates are shown at the bottom of the certificate. When your certificate expires you will receive an invitation to renew it, please make sure your contact details are kept up to date by emailing us with any changes to your postal or email address.

    Please check the data and details on the certificate.   If there is anything you think is incorrect please contact us; however for production designs remember some standard data may have been used which differs from that submitted (usually hull data).

    Ratings may go up, down or stay the same from year to year, depending on changes and developments in the maths behind the rating calculation.  This is developed on an annual basis and is generic for certain design characteristics.

    Age Allowance is automatically applied to boats over 3 years old, but it is a small part of the calculation. (It cannot be assumed that the rating will reduce each year because of age allowance).

    Crew limitations IRC Crew Number is not variable by a boat and has no effect on TCC (see also ‘Fair Play’ in the Yearbook).



    Amended or Trial certificates:   We cannot accept data by telephone.   Please make sure you complete the ‘Source of Information’ to avoid any delays, thank you.

    Note that there are limits to the number of trial certificates that are allowed, you can find details on the IRC website.

    We reserve the right to refuse to amend a certificate if we believe its purpose is to take advantage of a forecast eg. reducing sail for a race that is forecast to be windy.

    If you have an Endorsed certificate, remember that any amendments to rated data will require official measurement, please refer to our website especially regarding sail data and talk to the Rating Office for advice if necessary.

    Change of Ownership:  If you sell your boat and the new owner wishes to race it, or if you buy a boat with a current IRC certificate, then Re-Registration is required. 

    Short-handed certificates:  If you do short-handed (1 or 2 people) racing, and your boat is in a different configuration for this, you can apply for a separate Short-Handed certificate, see IRC Rule 8.2.1.  

    STIX and AVS Stability data :  If you are planning to enter an event that is OSR Cat 3 or over you may need to have STIX & AVS (stability) data on your IRC certificate. Please check the specific events you are entering, to see if it is required. Information about STIX & AVS can be found on the IRC website: Once obtained, the information will be added to your certificate free of charge as long as there are no other changes.


    IRC Rule changes 2017 – a summary

    • The definition of STL has been changed to cater for boats that do not use a spinnaker but fly a large headsail from the end of the bowsprit. All ratings will therefore include an STL measurement even if not rated for spinnakers.

    • To simplify the Rule, a new definition Aft Rigging has been added: IRC will no longer distinguish between backstay(s), running backstays or checkstays.

    • New rule 19.6 has been added requiring declaration of materials over specific gravity of 8.0 (eg. lead) in some types of keel fin. This is to counter the trend of moving lead from the bulb into the fin.

    • Rule 2.6 has been updated to reflect actual practice.

    • The new ERS 2017-2020 now incorporate definitions that were previously included in the IRC Rule, so these have been removed or updated as appropriate.

    • A number of detail changes have been made throughout the text to correct typographical errors and inconsistencies in terminology. 


    What should be aboard my boat for weighing?

    If you are having your boat weighed for IRC it needs to be in IRC Measurement Condition.  This is described in IRC Rule 17.1 and 17.2 and also applies to measuring the Overhangs and the Draft.

    One way we often describe it is that if you turn the boat upside down and shake it, nothing would fall out (although we don't expect you to actually try this!).


    2016 IRC Certificate - Year Watermark

    A security date watermark will be printed across all valid IRC certificates issued from 19 May 2016.

    This will make it quick and easy to identify a valid certificate (or copy certificate) issued by RORC or UNCL.