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:

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:

In Appendix E8 G.1.5 (b) (4) requires the prefix ‘1’ before a mainsail number only. Why?


This is a drafting error in the Appendix E rule E.8.

The following addition to the Standard Sailing Instructions used by IRSA Members for their events should be made.


1.4  Racing rule E8 will be changed as follows:

Add new G.1.5 (a) (6) ‘with sufficient space in front of the sail number for a prefix ‘1’.’

Delete G.1.5 (b) (4).


Question details:

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:

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.

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.



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.