What are the rules now on sail measuring? I used to measure IOM's last century and in those days I signed and dated every sail I measured. Nowadays I see lots of sails without signatures or dates so is that now the accepted norm?

Many thanks

Simon

Hi Simon,

As we use the same certification process across all NCAs, as controlled by IOMICA, the answer to your question is, if a sail complies in all respects with the checks as specified on the IOM Certification Control Form for rigs and sails check list (refer link below) then the Official Measurer shall sign, or stamp, and date the sail.

https://iomclass.org/wp-content/uploads/2026/04/Certification_Control_Form_Rigs_and-Sails_Check_List_202678.pdf

So the real answer is no and they need to be signed and dated or be stamped and dated at a minimum.

Regards,

David

Edited October 6Oct 6 by womble66
Typo

Thanks David, so a few unsigned sails about. I guess boats are built and sails measured and then sails replaced and not signed. Logically in that situation the sail maker aught to sign and date it because they have made it to spec and then the registration cert should be updated to reflect just that. Maybe one day it will be possible to update the cert online and just download it so no need to trouble a measurer?

I'll leave it to the MYA reps to comment but from my perspective as the National Registrar for another NCA, we don't accept sail makers certifying their own product but rather the onus is on the owner to ensure their IOM remains compliant and have any new sails certified independently by their NCA endorsed official measurers.

If new sails are not certified IAW the class requirements then they should not be accepted by an organising authority for use during an event ..... social sailing is another case.

Thats a fair point of view and very relevant to a some NCA's where the application of the class rule defines the sail area so it is incumbent on a measurer to ensure that the sail area is correct but with a class such as the IOM where the sail plan is defined in its external dimensions, if you are buying a suit of sails from an established sailmaker - and the sails are branded accordingly by them - then you would expect that the sails would satisfy the class rules as a matter of course and I imagine that any measurer of IOM's would confirm that that is the case? I have never found a suit to be lacking when measured in accordance with the rules anyway.

59 minutes ago, SimonCornes said:

....with a class such as the IOM where the sail plan is defined in its external dimensions, if you are buying a suit of sails from an established sailmaker - and the sails are branded accordingly by them - then you would expect that the sails would satisfy the class rules as a matter of course ...

It's a subject visited before, where people have sought to 'understand' the enforced separation between sailmaker and measurer.

Sail measurement https://www.mya-uk.org.uk/forums/topic/4446-sail-measurement/

3 hours ago, womble66 said:

... we don't accept sail makers certifying their own product but rather the onus is on the owner to ensure their IOM remains compliant

For sure the skipper must have the ultimate onus, but I reckon a sailmaker could be allowed to certify. Akin to a Company Director paying a fortune to a Chartered Accountant to prepare their year end accounts, but it's only the Director who is liable to HMRC for what is generated.

A sensible skipper would therefore buy from a reputable sailmaker who doesn't want to lose future business by being 'found wanting'.

Simon, a certificate does not need to be updated when new rigs are built. The certificate will have the same number of rigs as the original. The rigs do however need to measured, signed and dated.

Yes, of course, it just says A,B and C !

On 06/10/2026 at 15:56, SimonCornes said:

Thats a fair point of view and very relevant to a some NCA's where the application of the class rule defines the sail area so it is incumbent on a measurer to ensure that the sail area is correct but with a class such as the IOM where the sail plan is defined in its external dimensions, if you are buying a suit of sails from an established sailmaker - and the sails are branded accordingly by them - then you would expect that the sails would satisfy the class rules as a matter of course and I imagine that any measurer of IOM's would confirm that that is the case? I have never found a suit to be lacking when measured in accordance with the rules anyway.

As an IOM measurer, I can attest that I have had a not insignificant number of sails to measure from well known sail makers and I have had to decline to sign until the sail was bought into compliance... Common issue is sails where the leech falls outside the straight line either between the battens for the main or head to clew point for the jib.

4 minutes ago, Guzzilazz said:

As an IOM measurer, I can attest that I have had a not insignificant number of sails to measure from well known sail makers and I have had to decline to sign until the sail was bought into compliance...

Yep .... that's the main issue and while sails, rigs and boats should be measured by NCA endorsed independent official measurers ..... provides a level of assurance to the certification process.

Its not just sails ..... people who build boats and rigs should also not be involved in the measurement certification of those items where they have a direct conflict of interest in the outcome.

A fair and level playing field for all 😀

8 hours ago, Guzzilazz said:

As an IOM measurer, I can attest that I have had a not insignificant number of sails to measure from well known sail makers and I have had to decline to sign until the sail was bought into compliance... Common issue is sails where the leech falls outside the straight line either between the battens for the main or head to clew point for the jib.

Thats interesting Larry. I last measured an IOM about 30 years ago and the sails were by Sails etc and were perfect! I am surprised - and disappointed - to read that professional sailmakers are producing IOM sails which don't fit the Class Rules these days but you can only say what you have experienced so I guess those manufacturers need to pull their socks up!

With regard to that particular problem with head and mainsails I assume that a scalpel and a straight edge solves the problem and the owner is very surprised?

As Womble says, a measurer can't measure their own boat and never should. In my Club we had two measurers so that the pair of us could measure a boat or I could measure his latest and he could measure mine and we never expected any kind of favours from each other - what would have been the point? !!

Edited Friday at 17:243 days by SimonCornes

On 09/10/2026 at 18:22, SimonCornes said:

With regard to that particular problem with head and mainsails I assume that a scalpel and a straight edge solves the problem and the owner is very surprised?

Yep, and obviously not done by the measurer!

19 minutes ago, Guzzilazz said:

Yep, and obviously not done by the measurer!

Absolutely not by the measurer but if I was measuring then I’d provide guidance to an understandably nervous owner!