420 Measurement Certificates


The International 420 Class Measurement Form & Measurement Certificate

Also known as the World Sailing Certificate or the ISAF Certificate as these are the organisations who have issued this certificate over the years. World Sailing was previously called ISAF and changed its name in 2015, so earlier certificates say ISAF on the front.

When a 420 is new, it’s measured by an official measurer to confirm that it meets the requirements to be a 420, i.e. is the hull the right shape, weight etc. The measurements that the measurer takes are noted in this document and assuming these are all correct then this becomes the proof that your 420 measures and is legal.

This document is 8 pages long and importantly must have a red RYA stamp on every page indicating that it is a certified true copy. This document should be passed to a new boat owner when sold but does not need updating when boats change hands.

Examples of World Sailing, ISAF and Early ISAF certificates:


The RYA International 420 Measurement Certificate

In the UK, the RYA also issue a measurement certificate and to be compliant, a 420 must have both the World Sailing Certificate and a valid RYA certificate.

A new RYA certificate must be obtained from the RYA when a boat changes hands, putting the boat into the new owner’s name. New certificates can be obtained online via the RYA website or by contacting the Technical Department at the RYA.

Example RYA Certificate:

Certificate process for new boats

When a new boat is purchased in the UK you should receive the original World Sailing certificate with the boat confirming it measures. To obtain your RYA certificate you need to speak with the RYA Technical Department who will ask you to send them your original World Sailing certificate. They then keep a copy of this in their archive and send back to you a copy which has a red stamp on each page indicating that it is a certified true copy.

Once the RYA receive the World Sailing Certificate they then will have the necessary information to issue you with your RYA International 420 Measurement Certificate.


Buying a 2nd hand boat.

When you buy a 2nd hand boat it’s important you receive from the seller the World Sailing certificate. This is likely to be a red stamped copy. On occasion, boats have changed hands and the new owners have received the original World Sailing certificate. If this is the case, contact the RYA Technical Department and send them the original as per the new boat process above.

You may receive with your 2nd hand boat an RYA certificate. This will not be valid as it will be in the name of a previous owner, so a new certificate needs to be obtained in your name online via the RYA website or by contacting the Technical Department at the RYA.


Missing /lost certificates

If you purchase a 2nd hand boat and it does not come with it’s World Sailing certificate, then you can contact the RYA Technical Department to see if they have a copy in their archives (fingers crossed!) if they do, they can send you a certified true copy (red stamp) for a small charge. If they don’t have a copy on file, they can advise on how to get your boat remeasured by an official measurer who can complete and issue a new World Sailing certificate.

If you have lost your RYA certificate contact them for a replacement.


Hull weight, correctors and hull reweighs

When a new boat is measured the official measurer indicates on the World Sailing certificate the hull weight, the number of correctors and the total weight of any correctors used (if any). The minimum hull weight of a 420 is 80kg and as an example, the certificate may state:

The weight and corrector arrangement specified on the World Sailing certificate must also be specified on the RYA certificate. If there is a mismatch, then a new RYA certificate must be obtained so that it tallies with what is on the World Sailing certificate

420 hulls can sometimes get officially reweighed at a 420 championship. If this happens, the official measurer will complete the table on the back page of the World Sailing certificate with the new hull weight. Typically hulls get heavier as they get older and a reweigh may mean that some of your corrector weigh may come out. If you do have an official reweigh, it’s important that you obtain a new RYA certificate to ensure that the hull weight and corrector information on both certificates is kept in sync. The RYA will need to see the back page of your World Sailing certificate for them to issue a new RYA certificate with the updated hull weight information.


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