Question details:


The ERS is a document maintained by the ISAF which is a revised on the same 4 year cycle as the Racing Rules of Sailing. The current version may be found on the ISAF website and there are several versions in translation listed there too.

Question details:

What is the difference between a Q&A and a Class Rules Interpretation?


An interpretation is requested when it is not clear (to a designer, builder, measurer, class association or certification authority) how a class rule shall be interpreted. When an interpretation is issued it should be kept in mind that the interpretation is valid until the class rules are changed or for two years maximum only. The purpose of this last rule is that two years gives sufficient time to consider if the effect of the interpretation is a) desirable or b) undesirable. Depending on the decision or choice (a or b, by the IRSA TC or the class depending on whether there is an independent class organisation or not) the class rules can be revised accordingly.

Thus, when drafting any interpretation, it should be kept in mind how the class rules should/could be revised to make the original interpretation request redundant.

It follows that, if no revised class rule can be written, there is no need to issue an interpretation. Where no interpretation is required, but only an explanation of the effect of the class rules, it follows that it would be appropriate to deal with the original request by issuing a Q&A to be published on the IRSA website and elsewhere as appropriate.

This is the guiding principle used by the IRSA Technical Committee when considering any question about the class rules whether it is a formal request for an interpretation or not.


Question details:

At what point, on change of ownership, does the certificate become invalid?


The certificate becomes invalid upon a change of ownership. The change of ownership is the important criterion – not the signing of the certificate by the new owner – not the issue of the new certificate in the new owner’s name.

However, while the concept of ownership is normally well understood between any two people it may be that the law of the land becomes relevant in particular cases and this may vary depending on the contract involved and where the ‘transaction’ takes place.

The view is that IRSA class rules are not intended to, nor do they, shed any light on ownership or when it changes hands.

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Does an alternative sail have to fit within the profile of the 'largest' measured sail?

The 2002 class rules C.8.1 Limitations stated: "The profile of each alternative sail shall fall within the profile of the sails recorded on the certificate."

Is this no longer a requirement in the 2016 class rules?




Diff Profilesgb1No. Under the 2002 class rules it is required that 'alternative' sails shall fall within the profile of the sails recorded on the certificate. The 2016 class rules do not require this.

Sail makers will be aware that sails are 3D objects and small changes to the inbuilt shape at the seams will have an effect on the profile of the sail. Although apparently simple in its requirements, the 2002 class rule creates several problems. Unless the sailmaker knows the leech length of a sail he is replacing he is unable to make a sail of the same profile (even if it is a purely 2D object). Even 1 mm more, or 1 mm less, leech length or luff curve results in the profile of the replacement sail not matching the original. It is not smart to have a class rule that does not allow the owner to replace his equipment and easily meet the class rules. Further, unless the sails measured and recorded on the certificate are retained by the owner when he has replacement sails they, and the other 'alternative' sails cannot be checked according to the class rules.

The 2016 class rules no longer require alternative sails to fall within the profile of the sails recorded on the certificate but treat the issue in a slightly different way that solves the problems mentioned above and gives other benefits. How?

The way in which the 'largest' sail is placed on the measurement grid has been revised marginally - the head and tack are placed on a line perpendicular to the transverse grid lines with the clew placed on a grid line. At and above the clew the cross widths are taken as usual (but at 200 mm intervals instead). Below the clew the depths are taken at 50 mm intervals. The dimensions are recorded on the certificate.

'Alternative' sails are checked by placing them on the grid in the same way and checking that their dimensions (measured in the same way) are equal to or less than the certificate dimensions.

There is no requirement for these 'alternative' sails to fall within the profile of the 'largest'. This introduces freedom to have sails made with different luff curves (or fullness/camber for example) but which comply with the certificate. Any width added at the luff needs to be removed at the leech. Provided the cross widths measured at all grid lines remain less than or equal to the certifiate values, the sail complies. See the diagram above.

The sail maker has all the information he needs to make sails that comply with the class rules as extended by the boat's certificate without asking for more. At equipment inspection there need be no difficulty in establishing a sail's compliance under the 2016 class rules.

This freedom exists for boats with certificates to the 2016 class rules only. Boats measured to the 2002 class rules and any new sails made for them shall continue to comply with those class rules. 



Question details:


It is inevitable that a new set of class rules may have a rule which is thought to be in error or in need of amendment. Suggest a rule change to your DNM. If it agrees, or if you are the DNM, send it to the TC Chairman for further discussion. Please read carefully our regulations and Q&A to avoid unnecessary work before you send any suggestions to the TC. Proposals for rule changes should be based on meaningful technical evidence and not on loud repetitions.  

Question details:


An event can be run using "single certificates"

If it is considered desirable at a particular event to ensure a sailor cannot choose the best configuration to suit the prevailing conditions, the event organiser can issue a Notice of Race, and a Sailing Instruction, requiring a certificate to be lodged at some prescribed time ahead of the event and to use the boat in that configuation. This also prevents owners of multiple boats from choosing which boat to use at the time of the race.


Question details:

Does the Certification Authority have to use an official stamp in the relevant place when issuing a certificate?


There is no prescribed requirement for the size or style of ‘official stamp’. At an event the person inspecting the official stamp on a certificate has no means of knowing if it is the correct one or not. The important thing is that the issuing Certification Authority will recognise it at some future stage should the certificate be referred back to it for any reason.

Any size or style of official stamp will suffice providing the CA is happy that it can recognise it as authentic at a later stage.

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How large can the sail maker label be on sails? Or the manufacturer label on other items of equipment? The class rules do not restrict this?


The relevant rules are contrained in the World Sailing Advertising Code, also known as Regulation 20.

Clause 20.7.1 states that the display of manufacturer's and sailmaker's marks is permitted at all times as detailed in Table 2 but not in areas that area reserved for Event Advertising. For radio controlled boats the area reserved for Event Advertising is 40% of the hull length on each side of the hull from the foremost point on the hull. No Event Advertising is permitted on the boom(s), backstay or sails.

20.7.2 tells us a manufacturer's mark may include the name, logo or other identification marks of the designer or manufacturer of the equipment.

20.7.3 tells us that a sailmaker's mark may include the name, logo or other identification marks of a sailmaker or of the sail cloth manufacturer or the pattern or model of the sail.

Table 2 – Manufacturer’s and Sailmaker’s Marks

Radio-controlled boat

Hull  - On each side of the hull, and may include the name or mark of the designer or builder - One mark to fit within a rectangle measuring 15% of hull length x 150mm                     

Spars and Equipment - On each side of spars and on each side of other equipment - One mark not exceeding 50mm length                    

Sails - On each side of sails and kites - One mark to fit within a 50mm diameter circle






Question details:

Why are the spreadsheets that create certificates (M, 10R & A Classes) openly available?


Prior to 2016 there were two versions of the spreadsheet for each class.

In each case (M, 10R and A Class) the version available to the public (for use by official measurers, designers, sail makers and owners) allowed for data entry and calculation only and could not produce a certificate. The version made available to the IRSA DNMs only for use by their certification authority could produce a certificate. The idea was that it would be impossible forofficial measurers or others to have access to the certificate creation page.

In practice this did not work and the certificate creation versions were openly available. Recognising the way these things work in real life led the IRSA TC and EC to the conclusion that only one version of the spreadsheets is needed as it is the signature and official stamp on a certificate that authenticates it rather than the software from which it is produced.

Certification authorities are advised to take care to ensure that the method of signing and attaching their official stamp does not lend itself to illicit copying.

Each spreadsheet contains a (hidden) algorithm that finds a two digit code that is printed on each sheet of a certificate. The same code will be created each time the same data is entered. This is a simple precaution that confirms that the 'certificate' has been produced on the official IRSA version of the spreadsheet.

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Can the spreadsheets for creating certificates and other spreadsheet based certification control forms be used on Apple computers?


It seems they may not open and/or work correctly on Apple computers. IRSA does not have the resources to develop the same software to work correctly on Apple computers so, sadly, the options seem to be for official measurers and certification authorities to acquire the use of a pc or to use an emulator.

However, if you have been using IRSA certification material on Apple computers in the past, it is quite likely that you will be able to in the future.

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August 2018 changes to 2018 65 Class and Marblehead class rules. Why? And why have the Ten Rater and A Class rules not been changed?


The 65, M, 10R and A class rules have certain restrictions and limitations relating to booms. In 2018 it became apparent that the ERS definition of a boom - a spar attached at one end to a mast spar or a hull and on which the clew of a sail is set .... and its fittings - meant that the class rules did not work well for swing rigged boats.

The class rules for the 65 and Marblehead class rules have been changed by the IRSA EC - effective 1st August 2018 - acting to maintain the previous common understanding of the class rules. The A Class does not permit swing rigs so the class rules need no change. One DNM has provided a proposal to change the class rules in the 10R Class and so this will pass through the formal procedure for dealing with such proposals.

Please see the related Q&A - Does a typical rc yacht balanced headsail boom meet the ERS definition of a boom?

Question details:

Does a typical rc yacht balanced headsail boom meet the ERS definition of a boom?


The ERS definition states:

F.1.4 (b)  BOOM

A spar attached at one end to a mast spar or a hull and on which the clew of a sail is set and on which the tack and/or foot of a sail may be set. Includes its rigging, fittings and any corrector weights, but not running rigging, running rigging blocks and/or any kicking strap/strut arrangement.

The question is raised because the attachment of a typical rc yacht balanced headsail spar to the hull is not at the very end but some distance, typically 10-20% of its length, from its fore end.

For a definitive answer this question would have to be answered by seeking an interpretation from the WS ERS Working Group. There are certain problems with the ERS definition(s) relating to spars which have been made known to the ERS WG and it may be that a defnitive answer would not be made. In the meantime the following discussion is offered.

Points to consider

1     Where it is important to identify the very end of a spar the ERS has such defintions e.g. the mast top point and the mast heel point. If it were necessary to require the very end of a boom spar to be attached to the mast or hull then we can assume a 'fore end point' would be defined. It has not been and so we should not take the ERS defintion of boom to mean that the very end of the spar is the critical point.

2     Experience shows that all practical main booms are attached to the mast using a fitting with the attachment point some distance from the very end. As these booms are not attached at the very end we should be able to assume that the very end is not intended as the required attachment point.

3    Spars can be considered to have two ends and a middle. If each of these regions is 1/3 of the total length then the attachment point of a typical rc yacht headsail boom is well within the end region.

Question details:

Sailboat RC from Croatia (EU) as a manufacturer of IRSA radio sailing boats, its part and components has been warned about possible problems in the future with governments/customs regulations around the world dealing with the shipping of the parts made of lead.
According to the IRSA radio sailing Class Rules materials of keel and rudder shall not be of density higher than lead (11340 kg/m3 ).
Having in mind possible harmful consequences of using lead on the marine environment you are kindly asked to let us know whether the IRSA radio sailing boat bulb made of lead and coated with the long-lasting eco-friendly protective layer/coat is permitted.


IRSA radio sailing boat bulb made of lead and coated with the long-lasting eco-friendly protective layer/coat is permitted according to the current Class Rules of all IRSA radio sailing boats.
So far, World Sailing (WS) as the world governing body for the sport of sailing has not issued any ban on the use of lead as ballast in the keels. IRSA as the worldwide radio sailing organization and an affiliated member of World Sailing (WS) will follow their possible future guidelines/rules aiming to reduce the harmful impact of lead or any other material used in boat construction which may danger the environment.