FAQs

What does IRC stand for?

International Rating Certificate

What does TCC stand for?

Time Corrector IRC

For how long is my certificate valid?

All IRC certificates expire on 31st December of the year they are issued (30th May in some overseas areas, as printed on the certificate).  This is because the software is developed and updated at the end of each year.

You will be invited to renew your certificate just before it expires.

Can I hold more than one valid certificate for different configurations?

Yes, once you hold a valid primary IRC certificate, you may apply for a secondary valid certificate with a different configuration, e.g. sails, variable ballast. Please see Rule 8.2 for the full details.

Your  secondary certificate will have a different certificate number to your primary certificate. 

From January 2023 the shorthanded certificate is incorporated into the new secondary certificate, and there are more data that may vary from the primary certificate (see rule 8.2.1). When you revalidate an expired shorthanded certificate you will receive a secondary certificate.

Why are the rating formulae not published?

We believe the confidentiality of the IRC formulae is it’s main strength. It helps to prevent designers and builders producing boats specifically to ‘cheat’ the rule, thereby disenfranchising the existing designs for which IRC was created to cater.

My boat's IRC rating has lapsed for a few years, do I need to complete the whole new form?

This will depend on when the last valid certificate was, and what design of boat you have.  Please contact your local Rule Authority who will advise you or check with the Rating Authority about what is required for your boat.

I’ve just bought a boat which has a current rating – do I have to do anything?

Yes, the IRC certificate is invalidated by change of ownership so you will need to apply for ‘re-registration’. Please apply through your local Rule Authority. Some check measurement may be required.

Do you hold standard data for designs?

We hold complete data for IRC one-designs and standard hull data for hundreds of other production designs. For production boats (not one-designs) we still always require actual rig and sail measurements.

My boat has held an ORCi / ORR / other measured rating certificate – can I get all the information from that ?

Usually, yes, if the boat is still in the same configuration. From an ORCi/ORR certificate you can get all the data except: bow and stern overhang, y,h,x; FL.

Please send a copy of the latest certificate with your application.

Does my boat have to be weighed and/or measured by an official measurer?

No, unless you require an Endorsed certificate (see below), or your local Rule Authority or an event NOR or race organiser requires boats to be weighed/measured.

What is an Endorsed certificate?

An ‘endorsed’ IRC certificate is one for which the data on the certificate has been audited and if necessary verified by measurement or other methods. There is a set of common standards for the IRC Rating Authority and Rule Authorities to apply when endorsing a boat’s IRC certificate. See also “Accepted sources of data”.

Generally, IRC is a self-measurement system and this is acceptable for a Standard certificate. There is no general requirement for an owner to have his boat officially measured or weighed unless either he chooses to do so, or his Rule Authority and/or an Organising Authority for a race requires official measurement, generally resulting in an endorsed IRC certificate.

To apply for an Endorsed certificate contact your local Rule Authority. A payment may be involved.

Check measurement may be required on change of ownership or at intervals after original measurement.

Do all sails need to be measured, or only the largest ones?

The largest ones, plus the longest luff length of any headsail (HLUmax).

What changes on my boat need to be declared to the Rating Office?

Any changes which may affect the performance of the boat (see rule 9.6 & 27.1.).  If you are not sure whether you need to declare a change you are making, please check with your Rule Authority.

Can I remove items like the saloon table or other fitted equipment?

If items are removed, which are either standard on a production boat, or were included in the previous certificate, then this must be declared and may affect the rating. Removing items such as (but not limited to) table, doors, floorboards, toerails, cooking equipment, heads, berths, cupboards etc. will increase Hull Factor, as IRC discourages this practice as it is not within the spirit of the IRC Rule.

IRC Rules state (see current rule text for full formatting/definitions):

22.2 Hull Factor
22.2.1 Hull factor (HF) is calculated by the Rating Authority and is an evaluation of features of the boat and their character and efficiency.
22.2.2 Stripped out interiors, the use of light and hi-tech structures and/or materials, removal of furniture or other fitted equipment, etc. may lead to the application of higher than standard hull factor to compensate for potential increase in performance. Such features shall be declared to the Rating Authority.
22.2.3 The rated Hull Factor assumes that the boat is fitted out at least to the production specification and materials and/or to the condition when last measured/inspected. This does not negate owners’ responsibilities under Rules 8.9, 22.2.2 and RRS 78.1.

PRODUCTION BOATS:

The removal of fitted standard items SHALL BE DECLARED and, in addition to any decrease in weight, may incur an increase to Hull Factor as follows:

• table + 0.1
• any other items + 0.1 each

eg. a production boat from which the table, floorboards and 2 doors were removed could have the hull factor increased by 0.1 (table) + 0.1 (floorboards) + 0.1 (door 1) + 0.1 (door 2) = total HF increase 0.4.

NON-PRODUCTION BOATS (one-offs etc.)

The same may apply as for Production boats if changes are made to the accommodation and/or interior since the last application or information supplied for rating.

Full details of the items removed and their respective weights shall be advised to the Rating Authority via your Rule Authority.

How can I see what affect changes I want to make might have on my rating?

You can run up to 6 trial certificates; these are not valid for racing. See limitations and conditions below:

Trial Certificate Policy

The underlying purpose of an IRC trial certificate is to allow an owner to assess the effect of a proposed modification to his boat which because of the confidential nature of IRC he is unable to calculate for himself.

A parallel is what is known as a ‘designer trial’. This is a trial certificate issued to a designer based on design data before construction of a boat to enable the designer to estimate to the owner what the boat will rate.

Noting IRC rule 2.4: The Rule discourages unnecessary expense at all levels, it is essential that a trial certificate system is in place. However, it is also essential that this system is controlled to prevent abuse and hence ‘leakage’ of the confidential elements of the rule.

The Rating Authority has seen an increase recently in trial certificates and specifically in designer trial certificates giving rise to cause for concern about confidentiality. In the interests therefore of satisfying both of the above, the following offers guidance on the number and type of trial certificates that will be issued.

1. The Rating Authority reserves the right to refuse to issue a trial certificate without stating a reason and to amend these conditions at any time without notice and without stating any reason.
2. The following is given as guidance only. There will inevitably be exceptions which will be treated on an individual basis.
3. All requests for trial certificates shall specify definitive data. Trials of the form ‘What must E be to achieve a TCC of x.xxx?’ will not be issued.
4. Requests for trial certificates should be accompanied by a drawing showing hull, appendages, fitout, rig, etc. as appropriate. This will always be the case for designer trial certificates. The Rating Authority reserves the right to request further information before running trials
5. Discrete series of trial certificates, exploring the effect of incrementally varying a single variable, will not be issued.
6. Not more than 6 trial certificates will be permitted in any one calendar year for any existing boat. Not more than 3 of these may concern modifications to the hull or appendages.
7. Not more than 25 designer trial certificates will be issued to any one design office in any one calendar year. Within this number, not more than 6 will be issued in any 2 metre range of LOA, of which not more than 3 may concern variations to the hull, appendages or weight.
8. Requests for designer trials shall clearly identify the boat and any previous designer trials issued for that boat.

I need to amend some measurements / I want to run a trial certificate, what should I do?

Please apply through your your Rule Authority.  Application methods will vary depending on which country you are in.

How do I get a copy of another yacht's certificate?

Copies of any other boat’s last valid certificate can be purchased for a small fee. However, please see limits below:

IRC Copy Certificates

Due to a concern about the number of copy IRC certificates that are being supplied, the Rating Authority has a policy regarding the number and cost of copy certificates as follows.

• First 10 copies £12 each (ex VAT)
• Further 10 copies £50 each (ex VAT)
• Further 10 copies £100 each (ex VAT)
• No further copies will be permitted.
• No more than 5 copies of any single design class will be allowed.

The Rating Authority reserves the right to alter this policy at any time at it’s entire discretion.

Payment must be made at the time of request.

Can I see what measurement data was submitted for another yacht?

Only the measurements and data shown on the IRC certificate are publicly available, by buying a copy of their latest valid certificate.

How is age allowance applied?

Age Allowance in IRC is automatically included as part of the IRC rating calculation. It is based on the mean of Series Date and Age Date and starts when that mean figure is 3 years old.

Example 1:
Series Date 1995
Age Date 2003
‘IRC Age’ for age allowance = 1999. In 2019* age allowance started for boats with ‘IRC Age’ of 2016 or older, so for this example it would get 17 years allowance (2016-1999).

Example 2:
Series Date 2007
Age Date 2007
‘IRC Age’ for age allowance = 2007.

The amount of age allowance is small, not even 0.001 per year, and is just one aspect of all the many changes that take place in the formula each year. Hence ratings do not automatically reduce each year because the boat is older, but the age is taken into account in the TCC calculation.

Maximum age allowance is reached at 40 years (in 2023 this was extended from 20 years).

*example only

Will my rating be the same each year? Why has my rating changed from last year even though my boat hasn't?

Your rating may go up, down or stay the same from year to year, depending on how it is affected by program changes. It will not automatically go down each year due to age allowance, although this is an integral part of the TCC calculation. IRC is a ‘live’ rule. By this we mean that the maths behind the calculation of TCC is continually adjusted on an annual basis to reflect changes in design, sailing practice, etc. The changes affect generic types and characteristics, not individual boats or designs.

For more information on changes in specific years, see the Rule & Policies page under ‘Policies & Information’.

Why is my rating higher than that of a sistership?

Ratings are based on rated data; therefore any difference in measurements or other details may affect the rating.

My boat doesn't have a proper sail number - does it matter?

IRC rated yachts must have a sail number approved by their National Authority, please contact your local Rule Authority for advice.