2020 Edition of the OK Dinghy Class Rules

2020 Edition of the OK Dinghy Class Rules

Following the email vote at the end of 2019, the 2020 edition of the Class Rules has been published and is now available on the World Sailing website.

The rules can be downloaded here and came into effect from 11th May 2020.


The amendments are listed here:


2019 Class Rule Amendments

World Sailing has just published the rule amendments that were approved by the OKDIA AGM in February 2019 In Auckland.

The amendments have been included in the current rules along with many corrections of spelling, punctuation and formatting.

The amendments can be found here


The current rules can be found here.


Alistair Deaves
OK Dinghy Technical Committee

OKDIA Technical update August 2018

Download as PDF

In early July the OKDIA Secretary and the Chairman of the Technical Committee met with World Sailing technical staff in London to discuss the current class rule proposals and several other matters regarding class rules and wider class matters. The current proposals were approved in principle, giving us the confidence to take them into the AGM.

World Sailing were also impressed with the standard of technical competence within the class. As the class conInues its recent growth it is important that we maintain this level.

A few days later and the day before the 2018 AGM in Warnemunde, a meeIng of the Technical Committee was held to discuss the proposals and a few new suggesIons. Measurers and manufacturers were also invited. The discussions went well and a couple of amendments were made to the proposals for the AGM. These amendments can be found in the AGM minutes. The minutes of the TC meeIng can be found below.

The AGM was run is such a way that any proposals that were not going to pass were not voted on. All of the proposals except No 1 on CerIficaIon were voted on and passed. The indicaIon from the meeIng was that the TC should go back and take another look at the purpose and intent of this proposal.

Technical Committee, Measurers and Manufacturers meeAng 7th July 2018
Warnemunde, Germany


Chair – Alistair Deaves
Chief Measurer – Dick Batt
IM – Klaus Luttkus
OKDIA Secretary – Robert Deaves
TC – Jesper Standberg, Greg Wilcox, Alex Scoles, David Bourne (on behalf of Bill Bradburn) Manufacturers – Chris Turner (Ovingtons), JS, GW, AS
Measurers – MarIn von Zimmerman (GER), Ralf Tietje (GER)

1. Bevels.

The proposal 9 in the 2018 AGM agenda was discussed with the vast majority being in favour of opIon B. The feeling of the meeIng was that opIon A would leave too much scope for the “look” of the boat to be altered.

2. Cockpit Liners.

The meeIng then discussed cockpit liners. JS was concerned that the introducIon of a rule to allow liners would (1) produce more weight concentrated boats, especially around the
centerboard case capping, and (2) would make it more difficult for home builders to make compeIIve boats. Also that boats should be able to be measured to the current rules. AS, CT and RD (regarding the Synergy moldings) pointed out that current cockpit liners weigh much less that two plywood bulkheads and that providing the details in the proposal were adhered to we would not see heavy liners being used. The 70mm for the outside flange was chosen as this allows floor mats to fill the enIre area inside the flange thus making a better looking product.

3. Three piece masts.

The meeIng did not have any objecIon to this as it was unlikely a three-piece mast could be made faster than a two or one piece. The only issue would be interchangeable secIons and so event marks needed to ensure that masts stayed together during an event.

4. Gooseneck Pin

There was a discussion about including the pin/bolt in the weight of the mast. This was intended to stop the progression to ever more expensive and lighter bolts. The meeIng rejected the idea.

5. Hull CoaAngs

The new rules do not specify any limitaIon on the types of coverings that are allowed, as they do for spars and hull appendages. The meeIng agreed that they should be limited to paint, varnish, gelcoat, resin and vinyl. Also that the TC should monitor new products

6. Standard mast length

Several years ago AD asked all the builders for their building measurements in items such as deck height and pintle distance. As a result, some builders changed their molds and most deck heights at the mast are now 465-470mm. It was decided not to look to introduce a standard mast length at this stage but to publish all the available data with a set of recommended numbers for manufacturers to build to.

6. Open Forum

1. Weighing hull with centerboard. Would only work with engraved cerIficaIon numbers and a maximum weight. Idea rejected.
2. VerIcal Rudder. JS said the Danes were keen to look at this. JS will make a prototype and do some tesIng.

7. Padding

InterpretaIons of the padding rules have caused much confusion in recent years as builders seek to allow their customers to hike higher and further out. Ader some discussion it was agreed to modify the current proposal to specify that padding on the gunwale must fit within a box of 10mm verIcally by 35mm horizontally, on top of the 35mm x 35mm exisIng box. This allows padding on the sheerline to be lower than padding on the gunwale providing both are no more than 10mm above the sheerline. AD to arrange for a new drawing to be made with the padding box rule included.

Meeing closed.

New Class rules in effect from 1st June 2017

After a long time and very hard work, the Class Rules are now re-written in accordance with the ERS (Equipment Rules of Sailing) which should clear up a lot of grey areas in the Class Rules while keeping the spirit and basic measurements of the boats the same.

You can view and download the Class Rules from the World Sailing website.

The new Class Rules should always be downloaded from the World Sailing website, as that are the ones in effect at the time.


Update to new rules

The final process in completing the SCR conversion for the Class Rules is taking a little longer than expected. Since the decisions at the AGM there have been many other modifications and changes. These are mainly rewording and reformatting. Some new rules have been introduced but the majority of the rules will have retained their original meaning.

Last week in Barcelona representatives of the OKDIA met with World Sailing technical staff to talk through the few remaining issues. Most have been solved and will be incorporated into the latest draft.

The plan is still to have these new rules come into effect in the new year.

Errors and corrections in draft of new Class Rules

There will be some errors in the draft of the rules. To avoid the same error being submitted many times we will list them here as they are found. The error will be underlined and the modification will be in red.

  1. Diagram 9 (F 3.5 Spars Dims.) Boom outer band is shown as being measured from the aft face of the mast (‘extended sail track’ aft face) 2640mm Max. Rule F.4.4 gives boom outer band being 2640mm from ‘gooseneck hole centre’. (drawing will be modified)
  2. F.3.3 (b)  The spar extrusion shall include a fixed sail groove or track which may not or may not be integral with the spar. (….may or may not…)
  3.  C.8.4.a  Foreside of rudder or its extension to:
    (i) transom at deck level …………………………………………. ….. 45 mm
    (ii) transom at keel level …………………………………………. ….. 45 mm
    Difference between (a) & (b)   (i) & (ii) .…………………… ……. 5 mm
    Intersection of leading edges of rudder below transom ……  … 50 mm


Q & A: Open or closed rules

What is the difference between closed and open rules, One Design and Development rules? What are we currently and what will we be under the new rules?

Closed class rules are where the default is that anything not specifically permitted is prohibited.

Open class rules are where the default is that anything not specifically prohibited is permitted.

One Design rules are for classes where the boats should be as identical as possible within a defined set of small tolerances.

Development rules are for where the purpose of the class rules is to control the parameters defining a permitted boat.

The current set of OK Dinghy rules are termed as One Design. (Class Rule No. 1). As such, the measurement of the boat is controlled by the defined tolerances.

With the introduction of SCR, closed and open categories replace One Design and Development classes.

So under SCR/ERS, rules must either be catagorised as closed or as open. Alternatively each section can be either open or closed. If a section is open however, then it has to list everything (and that means absolutely everything) that isn’t wanted.

Open rules can be used for Development classes where there is no need for stringent equipment control and where there is no desire to keep the equipment the same. Hence the development. However in some cases closed rules would also work.

The OK rules are based on measurement and tolerance, and keeping the boats as identical as possible. So we cannot have open rules.

Given that our new rules must either be open or closed, the proposed new rules have to be categorised as closed. This is stated in the Introduction to the new rules and at the beginning of Part II. This applies to all sections in Part II (C – G).

To all intents and purposes closed class rules and One Design rules are the same thing. The only minor difference is that closed rules have to be completely inclusive. The current OK rules are effectively closed except for a lot of practices and equipment that we have always used and assumed were accepted, but in fact have never been mentioned in the rules. For example, the tiller is never mentioned so under closed rules it must be included. There are a lot more examples and one of the tasks of the conversion was to include all these ‘assumed’ parts and practices.

Further afield, if we take a review of the 40 centerboard International classes we find the following.

So far 20 classes on this list have adopted SCR. Of these 20 classes, 11 are manufactured classes and have little or no measurement control. The remaining 9 are measurement controlled classes. However, ALL 20 classes have closed rules.

No class on the centreboard international list has, as far as I’m aware, yet adopted any SCR based open class rules.

The fact is that nothing, or very little, will change in the conversion from One Design rules to closed rules. The benefits are that the way OK Dinghies are made and measured will be better defined and controlled, and the rules will be easier and simpler to enforce.

By saying that the new rules are closed rather than One Design, we also have a perfect example of how the new rules are clearer and more specific and by being so are removing some of the ambiguity of the current rules. To try and remove all ambiguity would surely be an exercise in futility, but reducing it as much as we can is one of the main reasons for making the conversion.

New Class Rules

The 2016 OKDIA AGM will vote on the adoption of a new set of Class Rules.

The attached draft of the new class rules is only a conversion from the current rules to the WS standard format. It should not have any different meanings or allow for different measurements from the current rules other than those necessary to get them into the standard format. Where the new rules differ from the current, they will be presented as proposals to be voted on at the AGM.

If you should find something which could have a different meaning or measurement than the old rules, and that is not mentioned in the proposals, please let the TC Chairman know about the difference, stating both the old and new rule.

If any questions are asked then the answers will appear in the Q and A section. Any comments will appear in this section as news updates.

The draft of the new Class Rules can be found here.

New Class Rules 2017

The notes and proposals arising from the new Class Rules can be found here.

Notes and proposals on the New Class Rules