One Design classes require all new boats to be measured in order to establish that they have been built in accordance with the Class Rules. Each new boat is issued with a Measurement Form (sometimes called a Worksheet), which has the detailed measurements made on the newly built boat. At this point, the new owner should apply to their National Authority (the ADA or CDA in our case) for a Measurement Certificate, which certifies the ownership and the measurement. You should keep both documents. In fact, the Dragon Class Rules say that you can't take part in Class races unless you have a valid Measurement Certificate.
Change of ownership invalidates the Measurement Certificate and it should be returned to your National Authority (ADA or CDA) who will issue a new Certificate to the new owner. This allows the National Authority to track ownership and confirm that all boats that are racing are indeed Dragons. So a Measurement Form is proof that your boat measured in as a Dragon and a Measurement Certificate is a record of ownership.
Sounds simple, but...
Does it really matter that much? Seems like bureaucracy. Well, if we want to grow the class as a One Design racing class in North America we need to follow the Class Rules. While we're just doing a little club racing or handicap racing it may not seem like a big deal, but when we have class starts and National Regattas, we need to start acting like a One Design class. And that means ensuring the boats are equal, to the best of our abilities. We have no existing class measurer on the continent, but there are a lot of things we can do before we take that step. And we have National Measurers from other classes who can help. It's pretty easy to measure the rigging and make sure we are in compliance with the equipment rules. The hardest thing to do is weight distribution and shape. But unless one boat is suspiciously fast, I don't think we need to organize a swing test or buy templates. If we want to host a Worlds again some time in this decade, we need to start now to do everything we can to comply with the Class Rules. While it's the individual owner's responsibility to keep the Measurement Certificate, the ADA/CDA have set up an online DropBox where electronic copies of these important documents are filed.
I can't find my measurement certificate. Check those old files from when you bought the boat. It's surprising what turns up. Ask the previous owner. Ask the builder, assuming they are still in existence. The builder is supposed to send a copy to the IDA, so that may be an option. Finally, send us an email to discuss possible options.
I am thinking about a big renovation - do I need to re-measure? Dragon Class Rules say that you need to re-measure after major repairs or major renovations. The also say you should consult the IDA Technical Committee prior to starting your renovation. And like all renovations, you need to "bring her up to code" - you will need to comply with the newest set of rules, not the one she was built under.
I don't race - do I need a measurement certificate? The short answer is no, although you should consider whether there might be an effect on resale price if you do not have one.