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The Boat

The OK Dinghy was designed by Knud Olsen (1919-2010) of Denmark in 1957. Since then it has become one of the most popular singlehanded dinghies in the world with more than 15,000 boats built in more than 40 countries worldwide.

Class Rules

For all rule related information, please go to the dedicated rules website:

The Class Rules can be downloaded from the ISAF Webpage:
OK Class Rules at ISAF pages (
Please be aware that these rules may change, if in doubt, ask the Chairman of the technical committee about the latest version, changes and interpretations.

The Class Rules refer to the Plans, you can get a printout of the plans from the okdia secretary for a fee + post & packing.
You can also download them for free here, note that the scan is not the best quality, but all details are readable. The plans are from 1986
These plans are to be used in conjunction with the current class rules that may supersede some of the dimensions and redefine the tolerances.
They are supplied for guidance only and the official aluminium templates take precedence. This is due to the possibility of the drawings distorting during the printing.

OK-Dinghy hull
(PDF, 1044 KB)

OK-Dinghy stem and foils
(PDF, 442 KB)


We have a list of manufacturers here.

Trim guide

Nick Craig wrote a brief trimming guide for carbon masts (around 2005), older guides are all still for alu masts.
Trim Guide (PDF, 48 KB)

Technical Manual

This Technical Manual is based on a print version from the british association.
It is very old, some information is based on wooden masts, while carbon masts are the standard, so take care with the information given, some might be out of date.
As some new OK sailors still find some information in this manual useful, we published it.
Technical Manual