Question details:

At certification, when the difference between the QBL dimensions is found to be outside the class rule limit, what is the correct action?


Large differences in the QBL lengths will occur due to one or a combination of the following:

  • lack of symmetry of the hull
  • placement of the hull off the centreline of the measurement equipment
  • lack of alignment of the hull with the centreline of the measurement equipment

As the permitted sail area can be increased (where there will be a QBL penalty) by enhancing the difference in port and starboard QBL measurements, the class rules specify a limit to that difference.

There is no requirement in the class rules for the centreline of the hull to be on the centreline of the measurement equipment. Moving the hull laterally on the measurement equipment can restore equality in the measurements. A rule of thumb that can help here is to move the hull one fourteenth (1/14) of the difference between the QBL measurements towards the side of the shorter measurement.

Alternatively, if the owner is prepared to lose some permitted sail area, the lower QBL dimension can be raised artificially to within the specified difference from the larger QBL dimension before recording.

Question details:

How close does the headsail tack, luff spar or boom swivel need to be to the centreline for compliance with A CR 8.4 (b)(2)


The word ‘approximately’ appears to introduce some latitude in the placement. As most boats are asymmetrical to a greater or lesser degree, making it impossible to define a centreline precisely, the requirement is that the attachment shall be approximately on the centreline.

For the same reason, it is impractical to state a maximum distance within which the attachment shall be made.

Generally, an attachment within 5 mm of the centreline will be compliant. Where a hull is conspicuously not symmetrical, this figure may be larger.

Question details:

When an A boat which has been originally measured under the previous class rules is remeasured, would that be under the current or the original class rules?



If a boat is being re-measured it is almost certain that this is because its flotation or other dimensions have been changed - that is A.11.1 a), b) or c) apply. A.12. 1 (b) is another possible reason. A.11.2 tells us what can be done when a boat ceases to comply with the class rules (which include its certificate) and option a) is for an official measurer to carry out certification control (i.e. re-measurement) of affected equipment (in this case, the boat).

The boat shall be certificated to the current class rules. However,  Sections D, E, F, G each tell us about possible grandfathering in cases where previously permitted equipment has become non-compliant due to class rule changes.

The hull shall comply:
(a) with the class rules in force at the time of its initial certification control;
(b) with the class rules relating to its certificate; or
(c) with the current class rules.

The hull appendages shall comply:
(a) with the class rules in force at the time of its initial certification
control; or
(b) with the class rules relating to its certificate; or
(c) with the current class rules.

(a) The spars and their fittings shall comply either with the class rules in
force at the time of the initial certification control of the hull or with the
current class rules.
(b) The standing rigging and running rigging shall comply with the
current class rules.

The sails shall comply either with the class rules in force at the time of their
initial certification control or with the current class rules.

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.

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:

An owner has purchased a boat and wants to register change of ownership. The boat, K4172, was registered in May 1989.

The previous owner(s) had not registered their ownership and can provide no certificate to the new owner. The CA has copies of the 1988 format certificates for the boat registered in the name of the original owner(s).

The new owner has the measurement form.

Note     K was the national letter for GBR in 1988.


What is required to obtain current certificate?

Can the boat compete without alterations?

Does the hull identification have to be brought up to date by using GBR instead of K?

Does the sail identification have to be brought up to date by using GBR instead of K?



At an event for Marblehead Class boats the current (2016, 2018 after 1st April 2018) Class Rules apply.

Section B states:

For a boat to be eligible for racing, it shall comply with the rules in this section.
B.1.1 The boat shall:
(a) be in compliance with the class rules.
(b) have a valid certificate.
(c) have valid certification marks as required.

The boat shall comply with the class rules and have a valid certificate. However, 1988 class rule 2.6.2 indicates change of ownership invalidates the certificate. Therefore racing by the new owner under the original certificate, even if it exists, is not an option.

The boat has no valid certificate. In order to race a valid certificate is required. CR A.12.1 (b) applies – by application of A.9. A.9 describes the process for obtaining a new certificate.


The boat shall be re-certified as per CR A.9.

The following points should be noted:
*The hull may comply with the class rules that applied at the time of its initial certification. This may be useful if any current class rule would prevent the hull from obtaining a certificate. On this basis the national letter in the hull may remain as K.

*The appendages shall comply with the current class rules.

*The rig shall comply with the current class rules.

*The sails shall comply with the current class rules or the class rules in force at the time of their initial certification. See 1988 CR 3.7.

*At world and continental championships the sail marks shall comply with the current RRS. The national letters shall be GBR.

*At other events the sail marks shall comply with the current RRS or the rules in force at the time of their initial certification. See 1988 CR 3.7 (f) to (h). Note that the use of national letters is not mandatory except at international events.

*If it is not clear when sails were certified they should be re-certified according to the current class rules.

Question details:

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.

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.

Question details:

 What equipment is optional for an A Class boat when racing?

This question is especially relevant to the Q&A concerning whether the boat may weigh less than the certified weight (less the tolerance).



Class Rule C.4.2 states that the boat shall sail with the hull, hull appendages, ballast, mast spar and main boom spar relating to the certificate. CR C.8.3 states the mainsail shall be set when racing. C.9.2 states rc equipment, if temporarily removed,  shall be replaced by items of similar weight in the same position. C.9.3 states the owner's flag is mandatory. CR F.1 states the rig shall consist of no more than one mast, one headsail luff spar, one main boom, one headsail boom, standing rigging, running rigging, wind indicators and owner's flag. CR G.1 states the sail plan shall consist of one mainsail and, optionally, one headsail.

From the above it is clear that the mandatory equipment comprises:

  • hull
  • hull appendages
  • ballast
  • mast spar
  • main boom spar
  • rc equipment of similar weight and position
  • mainsail

And the remaining equipment is optional comprising:

  • headsail luff spar
  • headsail boom
  • standing rigging
  • running rigging
  • wind indicators
  • replacement of rc equipment of similar weight and position
  • headsail

Question details:

When an A Class boat is raced without optional equipment on board, does it comply with the class rules when its weight is below the lower limit for boat weight because optional equipment is omitted?


The full text of the discussion and conclusion, under the 2017 CR and previous CR, will be posted here as a download. For the sake of brevity the conclusion is posted here:

The CR permit several items of the rig that shall be on board for certification control to be omitted for racing. The CR do not require sails to be on board during certification control. Further the CR permit the headsail to be omitted when racing.

It follows that the weight of the boat when racing is permitted to be lighter than the certified weight less the tolerance.

It follows that the weight of the boat when racing is permitted to be heavier than the certified weight plus the tolerance if the sails used weigh 200 grams or more.

At an event for A Class after 30th June 2016

At an event for A Class after 30th June 2016 the 2016 CR apply. Section C of the 2016 CR applies to all boats so this (discussion and) conclusion applies equally to boats competing under certificates issued under previous class rules.

Question details:

Should the 2016 software should be used when ownership of a boat first certified to the previous class rule changes?


No. The software for certification under the previous class rules should be used. Change of ownership causes the certificate to become invalid but it does not cause the boat to cease to comply with the class rules. A new certificate, to the previous class rules, shall be issued.

It is not possible to produce a certificate to the new class rules in the case of change of ownership because several measurements taken and used under the 2016 class rules are different to those used for the previous class rules.


A.12.1 A hull may be issued with a new certificate, showing dates of re-certification and initial certification as applicable:

(a) when a certificate becomes invalid upon change of ownership

by application of the new owner to the certification authority in the country where the hull is to be registered. The application shall include the old certificate and re-certification fee if required. In the case of an imported hull the certification authority shall request the measurement form(s) from the previous certification authority and a new hull registration number shall be issued,.

In this case there is no requirement to apply the procedure in A.9 (which describes how a hull is certified). Use of the software for certification under the previous class rules should be used.

Question details:

Should the 2016 software should be used when the owner of a boat first certified to the previous class rule elects to have his boat re-certified


A boat with a certificate first issued to previous versions of the class rules may have one or more alternative certificates issued using the process identified in CR A.12.1 (c).


A.12.1 A hull may be issued with a new certificate, showing dates of re-certification and initial certification as applicable:

(c) when one or more alternative certificates are requested to be valid concurrently with an existing certificate

by application of the procedure in A.9.

A.9 is the standard procedure for certification and no variation is necessary for a boat with a previous certificate.

Question details:

How does A Class rule G.3.2 (e) work where there are no batten pockets or battens?



G.3.2 (e) requires the batten pocket point to be found.

The batten pocket point is defined in the class rules as

"the intersection of the extended centreline of the batten pocket, or batten if there is no batten pocket, and the leech."

This case is much the same as a missing limit mark on the mast. If there is no batten pocket or batten the point cannot be found and the measurement cannot be taken. The official measurer should decline to sign the measurement forms (signing would indicate he had completed the task satisfactorily) or report that the measurement of the mainsail is incomplete on the measurement form and the certification authority will refuse to issue a certificate.

In practice the owner should be asked to add something that resembles a batten pocket (tape) or a batten (self adhesive glass sheet) in an appropriate place and the measurement (and in G.3.3) can be taken successfully.

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.

Question details:

What has happened to the previous interpretations? There were many interpretations to the previous versions of the Marblehead, Ten Rater and A Class Rules. Where are they now?


IRSA regulations restrict the life of an interpetation to two years - after that time any interpretation ceases to be valid. The reason for this is that it is expected that the class rules will be changed during the two year period to make the interpretation unnecessary.

Where the new class rules require equipment to comply with the current class rules, if the class rules incorporate the effect of the earlier interpretation(s), then clearly the intrerpretation(s) is no longer needed. This explains why some interpetations are no longer needed and have been removed.

Where the new class rules permit equipment to comply with earlier versions of the class rules (usually known as 'grandfathering') then the earlier interpretation, although expired, remains relevant and is retained for information. A few such interpretations are retained.

Many other interpretations that were issued in the period before 2014 have been revised and are presented here in the form of Q&As (see Q&A on the difference between an interpretation and a Q&A). Again, this explains why many earlier interpetations are no longer needed and have been removed.

Question details:

Can the aft QBL measurement points be on the transom?


1994 Class Rule

The 1994 A CR 3.2.4. states that "QUARTER BEAM MEASUREMENT POINTS are located on the surface of the hull one tenth of the waterline beam above the waterline and one quarter of the waterline beam from the centreline". The question is whether the transom is a part of the hull? Transom is a part of the hull according to the Equipment Rules of Sailing. Before the transom was included in the ERS definition of hull there was an interpretation in the Ten Rater Class that concluded the transom was part of the hull. There is, therefore, no reason to think that the definition of the hull in the Equipment Rules of Sailing, although not applicable for the 1994 A CR, should be unfamiliar to the average measurer/ builder/designer.

Quarter Beam Measurement Points may be located on the transom in accordance with requirements of A CR 3.2.4. Attention is drawn to the requirements of A CR 3.3.3 – the restriction on hollows in the surface of the hull apply equally to the transom.

2016 Class Rule

The QBL measurement points are required to be on the external surface of the hull shell (CR H.5.9). In ERS D.1.1 the hull is defined as 'The shell including the transom,.....'.


Starting in around February 2015, class rule changes were introduced and discussed within the IRSA Technical Committee. The proposed rule changes were circulated to IRSA Designated National Members (DNMs) around December 2015 and January 2016. A number of DNMs responded with comments, and these were addressed by the TC Chairman. The proposed revised class rules were then brought to the Executive Committee by the TC Chairman in March 2016, which the EC formally voted on and approved. The rules, and an explanation of the changes, were published in April 2016, and came into effect in July 2016 after minor errors were found and edits made. This is the process which has been used in the previous decades of rule changes by the IMYRU, ISAF-RSD, and now IRSA.  


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:

Use of boats with certificates issued by sources other than IRSA affiliated bodies?

Is it possible to enter an event described in the NoR and SIs as for boats of an international class (IOM,. M, 10R or A Class) with a certificate other than an IRSA certificate issued by a body affiliated to IRSA?



The IRSA international classes are distinct from classes using the same name but which are not administered (ultimately) by IRSA. For example the Naviga administered One Metre, Marblehead and Ten Rater classes are different classes and the certificates issued under those rules are not valid for IRSA events (world or continental championships) or events normally organised by IRSA affiliated bodies. The same is true for the Marblehead class administered by the American Model Yachting Association which uses class rules different to the international class rules.

The owner of a boat in one of those classes can obtain a certificate for the international class after having his boat measured to the IRSA class rule. To do this he should find an official measurer (please see the Equipment Rules of Sailing) and then contact his certification authority (normally the body in his country that administer rc sailing and is affiliated to IRSA). If he is a member of a body affiliated to his World Sailing Member National Authority (the body responsible for the administration of SAILING in his country) he will then be eligible to take part in events for the international class.

Question details:

A Ten Rater has its largest sails measured for the purpose of establishing its rating. Those sail sizes are entered on the measurement form and are recorded on the certificate. The same is true for an A Class boat and for a Marblehead (usually the largest of A rig, of B rig and of C rig). Is it necessary to have smaller sails measured and certified?



The smaller sails are measured to ensure they are indeed smaller and that they meet the other requirements and restrictions. Then they are certified (usually by the measurer signing the sails) to show that this porocess has bene completed satisfactorily.

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:

When the foot of a double luff sail falls below the lower limit mark, does it comply with the class rules?


The class rules (Marblehead and A Class) require that the tack point shall not be set below the upper edge of the lower limit mark. The tack point is normally aft of the mast spar but on a double luff sail (specifically a pocket luff sail) it may be forward of the mast spar. In this case it may be that the foot of the sail overlaps the lower limit mark (as shown on the diagram). There is no requirement in either class rule that the foot of the sail shall be above the lower limit mark.

A sail set as shown in the diagram complies with the class rules.

tack point_and_lower_limit_mark

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.

Question details:

Section C of the class rules requires the hull registration number to be displayed legibly on the external surface of the hull with a minimum height of 20 mm.

Section D of the class rules requires the hull registration number to be permanently marked on a non-removable part of the hull surface.

Can a single set of hull registration numbers satisfy both rules?


Yes. Providing the hull registration number digits are of minimum height 20 mm, are clearly legible, are easily visible, are painted, engraved, bonded in or moulded in, and are on a non-removable part of the hull then both rules are satisfied by a single set of numbers.

However, it is often more convenient and attractive to use vinyl numbers on the deck to satisfy the Section C rule and some more convenient method on an inside area to satisfy the Section D rule.

Bear in mind the purpose of the rules: the Section C rule is for the benefit of the race committee and other competiors at an event to help identify a boat when it does not have it's rig in place; the Section D rule is to permanently and uniquely identify a boat so that it may be grandfathered, if needed, at a later date. In 50+ year's time the number will also add value and interest to any boat that has survived that long.

Question details:

A recent ruling for the IOM class says the certification authority for the hull is the DNM of the country where the owner is resident.  Does this apply to the M, 10R, and A Classes too?



The IOM, Marblehead, Ten Rater and A Class class rules indicate the certification measurement forms (measurement forms) are sent to the certification authority in the country where the hull is to be registered. This seems to give the owner some choice over where his hull is to be registered.  However, ERS C.3.1 defines the certification authority as 'the MNA of the owner'. Where the term certification authority is used it shall be understood to be the certification authority in the country where the owner is resident or in the country of which the owner is a national. This is normally the DNM (Delegated National Member for radio sailing) in the country.

Question details:

Who issues a certificate for any of the IRSA classes?






The certification authority issues the certificate. As of 1st July 2016 all the IRSA classes have the same administrative section. It is A.9 that indicates it is the certification authority that issues a certificate.

The term 'certification authority' is defined in the ERS as:

For the hull: the ISAF, the MNA of the owner or their delegates.

For other items: the ISAF, the MNA of the country where the certification shall take place, or their delegates.

The members of IRSA are the bodies to which the administration of RC sailing has been delegated (if not the MNA of the country itself) and which are known as the DNMs. So, for the hull it is the IRSA DNM of the owner.

For other items it will usually be the same but it could be the MNA or delegate of MNA in another country where the emasurement took place. This would apply where, for example, sails were certified in house by a sailmaker who had been delegated the authority to do that.

See also the related Q&A concerning who is the certification authority, or DNM, for an owner.

Question details:

What sail identification marks shall be displayed when a hull holds a certificate in more than one class.


When a boat races it shall carry the appropriate sail identification marks for that class. Providing they do not affect the legibility of the marks, alternative class insignia may remain on the sails.


No. C.6.3 prevents the movement, articulation, retraction or extension of hull appendages (including the ballast). Additionally RRS 51, which is not excluded by Appendix E of the RRS, states that movable ballast ‘for the purpose of changing trim or stability’ is not allowed.

1994 CR 4.1.1 prevents movement of the ballast fore and aft and canting keels per se are not prohibited. However, when a race is un using the RRS and RRS 51 is not cancelled the effect is the same.

The same logic applies to the other classes too.


Yes. Class rule C.7.2 applies to the spars, which may not be replaced unless lost or damaged beyond repair, and does not apply to the rigging or fittings on the mast and main boom.

The 1994 A Class rules do not use the ERS definitions so the requirement to use the original mast and/or main boom should be understood to apply to their spars i.e. the structural members to which fittings and rigging may be added.

Owners are reminded that the boat shall still comply with other class rules (weight, flotation etc) that may be affected when rigging is changed.


Except when the original mast spar or main boom spar are damaged, no. CR C.7.2  permits that the mast spar and main boom spar, when lost or damaged beyond repair, may be replaced with the approval of the race committee.

C.4.2 requires the boat to sail with the mast spar and main boom spar used when the boat was measured for the certificate in use at the event.

The clear implication of C.4.2 is that if the mast spar or main boom spar are replaced then the boat shall be re-measured. If the boat complied with its certificate (and the dimensions on it) no further action is required. If it does not comply with its certificate then the necessary adjustments shall be made to the boat and/or the measurements forms and a new certificate shall be issued.

The 1994 class rule has the same effect.

Question details:

Is it permitted to have a small raised area of deck to house mast partners and a mast ram at the mast point and a small recessed area just aft of that point?


Yes. D.2.3 (d) (1994 CR 6.3.5) allows for a limited amount of transverse deck round, being 1/24th of the beam at any point. The class rules do not place any fore and aft or transverse restrictions on deck camber, only that it shall not exceed the permitted amount.

Question details:

Is the extension fitted to the sails in the photograph to be considered as part of the sail or as a halyard? If the extension is part of the sail then:

  1. Do these sails comply with G.3.2 (b) (1994 CR 6.3.1)?
  2. Where is the head point?
  3. How are the "correct positions" of the battens to be found for clause G.3.3 (1994 CR 6.3.2)?
  4. Do these sails satisfy the requirements of measurement form item 10 (1994 MF item13)?



a      Yes. The upper part of each sail is clearly not separable from the remainder of the sail and is therefore part of the sail. Taking the individual points raised above in turn:
The class rules are open class rules and therefore anything which is not specifically prohibited is permitted. CR G 3.2 (b) requires the mainsail to be trilaterial and bounded by the luff, foot and leech. There is no rule which prohibits a concave leech but hollows shall be bridged as described by ERS H.5.2. For the 1994 class rules the IYRU SMR describe how to handle measurement of a sail with a hollow leech. The sail is not a quadrilateral sail and has the three required edges. Restrictions are placed on the shape and size of the sail elsewhere in the CR and the sail shall comply with those restrictions.

b      The head point is defined in the ERS G.4.2 and is found as the intersection of the luff, extended as necessary, and the line through the highest point of the sail at 90 degrees to the luff. For the 1994 CR the IYRU SMR apply but the effect is the same. The design of the sails referred to does not affect this measurement.

c      The batten position is limited as in G.3.3 (1994 CR 6.3.2). The design of the sails referred to does not affect this measurement.

d      Yes. See (a) above.

Question details:

Can a boat with a certificate in one class also hold a valid certificate in another class?


There is no rule in any of the International One Metre, Marblehead, Ten Rater or A Class class rules which prevents a boat from having a valid certificate for another class.