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Jeremy Arnold 1552

Getting the Measure of things

Explaining the Flying Fifteen measurement process from the boat owner’s point-of-view

Part One – An overview of the measurement process


Boat measurement is one of those things that we all think we understand but few of us have actually been through: - Although nothing about the process is particularly difficult there is nonetheless a learning curve to climb when first taking a boat through measurement and this article may help make that climb a little less steep.

First, to state the obvious: - the Flying Fifteen is a one-design class with no limitations on who can build hulls or supply equipment. Thus, a Flying Fifteen doesn’t actually become a Flying Fifteen until it’s been through a comprehensive measurement process to ensure that it complies with the class rules; it’s worth emphasizing that it’s the issuing of the measurement certificate, not the issuing of the sail number, which is the critical point here – in fact the boat must have already been issued with a sail number before measurement can take place.

Who does what?

As an International class the Flying Fifteen class rules are administered by its international class association (FFI – Flying Fifteen International), with FFI’s Chief Measurer being Graeme Robinson of New Zealand. FFI oversees the various National associations (UKFFA in the UK), and each of these also has its own Chief Measurer (Simon Patterson in the UK) plus a team of Official Class Measurers and Maintenance Measurers.


Sailing as a sport is governed internationally World Sailing and their role includes the governing the Flying Fifteen class rules along with those of all other class associations. Operating beneath World Sailing are various National sailing authorities, with the UK’s being the Royal Yachting Association, and thus it is the RYA that is the certification authority for the Flying Fifteen class.

Full measurement of new boats – and the re-measurement / re-weighing of existing boats - can only be carried-out by Official Class Measurers ratified by FFI. Other tasks – essentially those from Rule B9 onwards in the class rules – can also be carried-out Maintenance Measurers, and sails can also be measured by In-House measurers appointed by World Sailing or a National governing body.

Pre-championship check-measurement, incidentally, can be carried-out by any person acting under the supervision of a class measurer.

Reasons for Measurement

The primary point at which measurement takes place is of course when a boat is newly built, but the class rules also require full measurement when ‘substantial alterations to the hull’ have been carried-out to an existing boat, or indeed if a hull has been entirely replaced. Owners of Classics & Silvers should note that such hull alterations may also result in their boat being reclassified into a different fleet.

Partial re-measurement of existing boats may be required on the instructions of World Sailing or their affiliates (i.e., the RYA etc) or by FFI or its affiliates (i.e., UKFFA etc), or by an event Race Committee.

Partial re-measurement of an existing boat in the form of re-weighing might also be instigated by the boat owner themselves once 12 months have elapsed since first measurement. Note that the re-weighing still requires the keel, buoyancy, cordage and other equipment to be removed from the hull and that any corrector weight changes must be officially recorded and a new measurement certificate applied-for.

As already mentioned, new sails are now often supplied pre-measured, but if not, the boat owner will need to arrange for this to be done - and note also that the details of any new sails must be recorded on the boat’s measurement certificate by a class measurer (i.e. not just added by the owner), in order to ensure compliance with class sail limitation rules.

Lastly, with the exception of pre-measured sails, owners should be aware of rule A8 if they intend to replace any of the measured components on an existing boat - it being their responsibility to first arrange for the legality of the replacement component to be checked by an appropriate measurer. In other words – if a replacement mast is required the owner should first arrange for it to be inspected by a Maintenance Measurer, and if a new rudder is to be fitted then the services of an Official Measurer will be required.


Part Two - A practical guide to the measurement of new boats

The information below is intended primarily for those owners who are either building a new Flying Fifteen from scratch or (much more likely) fitting-out and completing a bare GRP hull.

Firstly a quick word about Measurer philosophy:- Everything you’ve read in this article so far may have given you the impression that the measurement process is strict and highly regulated, and while that’s technically true it doesn’t mean that Measurers are in any way ruthless or unsympathetic…In fact quite the opposite is true and all our class Measurers are great Flying Fifteen enthusiasts who will bend over backwards to help owners and builders, and who will do their very best to help you get your boat through measurement - so don’t be afraid to ask if you need help or advice at any stage of the build process.

There now follows an uncomprehensive and non-official step-by-step guide getting your new boat measured and registered: -

During the building stage

The Flying Fifteen class rules are available to download from the FFI (not UKFFA) website, and builders should obviously make themselves familiar with the relevant rules before tacking each aspect of their build.

In terms of fit-out you will find our class rules generally much less restrictive than those of many other classes, but be aware that in some cases several rules interact with each other and must considered together before you start drilling holes; a prime example of this being the relative positions of the chainplates, mast gate and furler mounting points. Don’t do as I did and start by copying the chainplate positions from another boat on the assumption that “they must be right”, only to then have to move them further back after realizing that I’d unnecessarily restricted where the mast could sit within the gate.

Note that if your build includes constructing a rudder or finishing a keel it will be essential to have a copy of the keel & rudder templates (Plan 97/2) in addition to the rules themselves. The class Secretary will send you these as an email attachment upon request, with the attachment taking the form of a PDF file containing a technical drawing showing keel & rudder in profile and section – with the horizonal and vertical sectional views provided matching those of the official measurement templates. So, by getting the PDF file printed-out at exact full size by a plan printing bureau you can then create your own temporary set of measurement templates and thus be certain that your keel and rudder will measure correctly


Also, essential if finishing your own keel – and useful if just fitting-out a hull – will be your own set of scales. I remember years ago hiring a 500kg digital loadcell at some expense to weigh a Flying Fifteen, but nowadays you can buy the same thing outright for less than £50. Whilst my boat was being measured earlier this year, I very cheekily did a side-by-side comparison test of my scales against UKFFA’s official set and found the readings to be all-but identical.

It's worth buying your own set of scales

Preparing the boat for measurement

It’s natural to regard measurement as an irksome hurdle to negotiated during the build process, and you may be tempted to get the boat over that hurdle as early as possible on the basis that the keel and various other items cannot be fitted until it’s been completed.

This isn’t good practice though since a major element in measurement is the official weighing of the boat, and in order to be sure that you’ve maximized the recorded weight (and thus minimized the required correctors) it’s far better to get the boat as fully finished and ready to sail as possible, then go back and remove the minimum number of non-permitted items required for weighing to take place. As part of this incidentally it’s perfectly acceptable to ‘sew-in’ certain ropes to render them ‘fixed equipment’ rather than removable rigging, and it’s sometimes also possible to ‘hold-up’ loose cordage during weighing to prevent it’s weight registering on the scales.

It should be noted incidentally that the class rules do not permit weight to be added to the hull which is neither necessary for the boat’s construction or fit-out – ie. you cannot add your own ‘unofficial’ weight to the hull before it is measured and before the official corrector weights are fitted.

Items which may not be fitted to the hull during weighing are listed below, but bear in mind that many of these items must still be presented for inspection as they are subject to their own measurement:

  • Keel
  • Keel bolts (see note below)
  • Rudder, tiller & tiller extension
  • Spars, inc. spinnaker pole(s)
  • Sails
  • Removable cordage & rigging
  • Removable buoyancy **
  • Equipment such as paddles, hand bailers, compasses, pumps etc

[** This is in fact incorrect. Class Rule 8.1 makes it clear that removable buoyancy is weighed as part of the hull.]

The rules specify that “keel bolts or studs” are weighed with the keel; no mention is made of nuts but Measurers take these to also be included since a stud with a nut is the equivalent of a bolt. What aren’t include in the keel weight though are keel bolt washers or backing plates, but fortunately a little glue or double-sided tape will render these a permanent fitting for hull-weighing purposes

Finally, it’s worth mentioning that some items – hand bailers, a paddle, an anchor and so on – are required by the class rules when racing but are not part of the measurement process. But these items – plus other equipment such as towing lines – WILL be inspected on other occasions, such as during event scrutineering.

Arranging Measurement

Although you can register your new boat at any point this is again something you ideally want to leave until the last moment to be sure of receiving the latest possible sail number - which you’ll then proceed to carve into the hog of your hull using a Dremel or similar.

Sail numbers are issued by the Secretaries of each National association on behalf of FFI upon payment of the Registration Fee, part of which is passed on your behalf to World Sailing and in return for which you will later receive a World Sailing plaque (i.e., the familiar blue sticker) for attachment to your boat.

At the same time as paying the Registration Fee you’ll probably also be paying the Measurement Fee which pays the expenses of the individual Measurer who’ll be coming out to inspect your boat. By this point you may have already contacted your nearest Measurer (see FFI website for a list of names), but if not, the class Secretary will put you in touch with the right person. Then it’s just a question of arranging a time and place with them, the only requirement for the latter being the availability of a chain hoist or similar to lift the hull and keel for weighing.

As the boat owner / builder you’ll be expected to be present whilst measurement takes place, and will no-doubt find yourself holding the end of tape measures at times and assisting generally. And of course, you’ll need to have already worked out the logistics of moving the separated keel and hull around so that the Measurer can weigh them.

Note that the keelbolts are included when weighing the keel

About the Measurement process itself: -

All new Flying Fifteen hulls and foils are subject to full measurement, although owners with moulded GRP hulls or rudders should have no concerns. Keel can be a different story though since every keel is a one-off both in the way it is cast and the way it is hand-finished. Keel measurement tolerances are quite tight too, and this is exacerbated further by the current trend towards ‘keel chines’ – in other words finishing the bottom edges of the keel with a corner rather than being fully rounded as shown on the keel plans.

Don't overdo those keel chines!

After the big day

During the measurement process itself the Measurer will have recorded the details of your boat into an 11-page class measurement form and will have course have discussed with you any issues that may have arisen.

If there were any failure points it’s now your job to carry-out any rectification work required and submit those items for re-inspection – which in a worst-case-scenario, for instance hull shape discrepancies or an under-weight keel, might mean arranging a whole new measurement appointment.

The other thing that the Measurer will have told you is the total corrector weight required by your boat, and you now need to create and fit one or more correctors to make up this total. Correctors are usually made from lead sheet cut to whatever length your scales tell you is required, then folded into a block and securely bolted (“through fastened”) into the boat. Each corrector must have its weight marked on it and be mounted such that it is “clearly visible in the cockpit area” - which can include bolting it to the hog beneath the removable floorboard

Once the correctors are in in place the measurer will wish to arrange some form of inspection to ensure they are fitted to the specification required in the class rules, and of course your boat will also very likely be weighed and the correctors checked on future occasions during pre-event scrutineering.

Once your Measurer is satisfied that everything is in order he will complete and sign your boat’s measurement form and send it to you by post (and buy him a beer next time you see him!), whilst the class Secretary will issue you with the aforementioned World Sailing plaque.

The final step in the measurement process is to actually apply for your measurement certificate, which the RYA will issue to you upon receipt of your signed measurement form (which they will return to you) and payment to them of the required fee. Once you’ve received your measurement certificate remember that it will need adding to it the details of any sails you will be using on the boat.

Oh, and at this point you can bolt your keel on and go sailing!


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