Technical Information

The Firefly was designed as a low cost One-Design racing boat over 70 years ago. The National Firefly Association is always working to ensure that the class remains true to this ethos, so Firefly owners can continue to enjoy low-cost, competitive racing for many years to come.

Here are some notes that will help you with any technical questions you might have.

Class Rules

The National Firefly Class rules cover every aspect of the Firefly no matter how old or new. Every boat must conform to the class rules to take part in Firefly Events. PLEASE REMEMBER: IF THE RULES DO NOT EXPLICITLY SAY YOU CAN, THEN YOU CANNOT!

The latest rules can be downloaded from the RYA website here 

Technical Secretary

The tech sec is responsible for ensuring that all boats are legal and conform to the Firefly class rules. As well as helping out owners with modifications and rule related questions. The current Chief Technical Secretary is Guy Davison. Guy is supported in his role by Assistant Technical Secretaries Alex Ogilvie and Alex Baxter.  Please contact them through the ‘committee’ page if you have any questions.

Firefly Community – “The Swarm”

The other great place to get advice (especially on rigging, tuning or detailed “wood” questions) is from the Firefly Community. There is a forum on this website as well as extremely active communities on Facebook, Twitter and Instagram. However ‘obscure’ your question might seem it’s a pretty safe bet, if you have a question, that at least one person of the fleet has had the same thought at some point!

Measurement Certificates

The Racing Rules of Sailing, Rule 78.1 states:

78.1 A boat’s owner and any other person in charge shall ensure that the boat is maintained to comply with her class rules and that her measurement or rating certificate, if any, remains valid.’

Under this rule, the Royal Yachting Association (The National Authority for the United Kingdom) require International and National Class boats racing within the United Kingdom to obtain and maintain a measurement certificate as required by their Class Rules.  It is the owner’s responsibility to obtain such certificate and to maintain his boat to the standard required by the class rules.

To prove that your boat conforms to the class rules you must have a valid measurement certificate in your name.   The RYA offers this service for a small fee (£30 for Non-RYA-Members, £15 for RYA members and £60 for a university fleet of six).

New Boats – First Certification

When you take receipt of a new boat (or boats) you will be issued with a partially completed Measurement Form and builder’s receipt.

In order to issue a measurement certificate to a boat, the RYA will require a fully completed copy of this paperwork and the appropriate certification fee (£30 for Non-RYA-Members, £15 for RYA members and £60 for a university fleet of six). The RYA will also require your name, address, the club you sail at and the name of the boat. We operate a “unique boat name” and therefore there is space on the form for a choice of three names.

Upon receipt of all the documentation and fee, provided that all is in order, a measurement certificate will be issued. This measurement certificate will be valid provided no alterations are made to it. If the boat is sold, a new measurement certificate will be required in the new owners name. If any of the details regarding the boat change; for example, the boat is reweighed and a different weight is recorded, then a new measurement certificate will be required.

If you’ve bought a new boat and haven’t been given the Measurement Form make sure you chase Rondar for it.

Older boats – Re-Issue of a Measurement Certificate 

When a boat is sold the Measurement Certificate will become invalid so if you have purchased a preloved boat it will need to be re-registered to you before you go racing.

If your boat came with certification paperwork it is just a matter of applying for a new certificate in your name. If the boat came without certification you should contact the RYA technical department to find out if the boat has a “historic” certificate.  If the boat has never had a measurement certificate or has undergone substantial modification since last measurement then it will require a full measurement by a RYA approved Firefly measurer before a measurement certificate will be issued.

You can apply for a new certificate online here. Please ensure you are signed into the website, or register if you have not done so. Then go to ‘Your Account’, following the link found on the top right hand corner of the page. On the left hand side of your screen there will be a list of links including ‘Measurement Certification’. Please follow the online instructions. For more detailed directions, please see the document ‘How to Order Online Measurement Certificates’ 

There is no grandfathering process within the class rules. If  any modifications are made to a boat (re-deck, new centreboard case, new rudder, major repair, compete rebuild etc) it must be re-measured by an RYA approved Firefly measurer. They will measure your boat and fill out a new Measurement Form which you must send of to the RYA with your original Measurement Certificate to be issued with a valid and up to date certificate.

The RYA Technical Deparment’s phone number is 0845 345 0383, 023 8060 4202, 023 8060 4289.  The RYA charge a small admin fee (£30 for Non-RYA-Members, £15 for RYA members and £60 for a university fleet of six)

Duplicate Measurement Certificates

Any owner requiring a duplicate measurement certificate is required to pay the flat rate fee, even if they are a member of the RYA.

Certification Fees & Express Certification Fee

The fees for Measurement Certification are the same for new boats and change of ownership or detail. All prices below are inclusive of VAT.
Full/Junior Member of the RYA – £15.00
Non-member – £30.00
Duplicates or Replacements – £30.00 (no discounts applicable)
RYA Gold Members – 1 free certificate per calendar year

Express Certification Fee  – A fee of £20.00 will be levied on all certificates issued within one week of the first race of the National Championships of that year, or during the event itself. This is in addition to the normal charge of £15/£30 for RYA Members/non Members, or for Gold Members the fee will be £20. The Express Fee is an incentive for sailors who knowingly enter their Class National Championships to do so with the relevant documentation in place.


These are people selected by the National Firefly Association and the RYA as persons who can measure your Firefly. If you need to have your boat or any part measured contact one of the committee, who will put you in touch with your nearest measurer and arrange to meet you to have your boat measured. It is the boat owner’s responsibility to get the boat to the measurer or cover the measurer’s expenses as they are volunteers.

The current measurers are:

Name Location
Damian Boreham London
David Chivers  Brightlingsea
Gordon Currey Cheshire
Brian Herring Cheshire
Chris Howe Oxon
Steve Greaves Woking
Jamie Marston Wirral


Measurement is a responsible job that requires skill and accuracy to understand the rules. If you are interested in becoming a measurer please contact Guy Davison to have a chat about the role.

Buying a Boat


Rondar Raceboats ( ) are the only approved builder of new Firefly hulls. or, for a more traditional look, Tony Thresher ( uses the Rondar hull shell to build a stunning composite option to the MK1a, MK3 or MK4 wood deck specification.


Just like the famous watch brand you never truly own a Firefly, you just look after it for the next generation.

There is a really strong secondhand market for Fireflies and boats of all ages and marks are readily available.

Otherwise places to look at include Yachts and Yachting or Dinghy Trader


To keep the one design, Fireflies have only one sail maker this keeps the costs down and everyone on the same performance. So if you buy a new suit of sails you know that your sails are identical to the fastest boat in the fleet. The current class sailmaker is Hyde Sails.

You can save a stack of money *and* earn commission for the National Firefly Association by buying your sails through us. To buy sails through the NFA at a discount visit this page


Since their aqusition of Procter Masts, all Firefly masts and booms are made by Selden using the same design. The Firefly mast and Boom are what is known as “C” section. If you ask any chandler who sells Selden they will be able to supply you with a Firefly mast or boom of the current design. For Selden stockists visit

“older-style” short or rotating masts are no longer in production. So is not possible to buy a new like-for-like replacement. You can always upgrade to the current version very easily with minimal alterations. If you’re determined to keep your boat original the best way to get your hands on older masts is via the chat page as people often have them lying around in gardens or sailing clubs and are keen to get rid of them.

Jib-sticks are an “open item” and may be supplied by any manufacturer and can be made out of any material. The only stipulation is that they must be no longer than 1220mm max including fitting ends. There are many stick configurations on the market however, Pistons both ends are preferred by crews as they allow you to gybe with pole up.


If you need a new rudder most rudder manufactures can make a new rudder for you. The NFA have an arrangement with Alan Powell (ex Quicksilver Foils) who will build you one to your spec i.e. lifting/foxed/laminated etc. You get a £20 discount if you are an NFA member. Contact Alan on 01844 201243 or email

If you need a new centreplate either try to locate a second hand one via the discussion forum or for a new one via Rondar.

I hope this has covered most technical aspects of the Firefly if in doubt please do not hesitate any member of the Committee and I am sure they will be happy to help.

2008 Tuning Guide

Position 2008 Nationals 1st 2nd 3rd 4th
Helm/Crew Paul and Laura Kameen Tom Malhindine and Alice Currey Mark Tait and Sally Wakefield Stuart and Jane Hudson
Boat Biscuit Buffalo 2108 (wood, mark 4) Bloodhound 2594 (wood, mark 1a) Dido 498 (wood, mark 4) Fursty Ferret 3850 (plastic)
Mast Fixed (long) Fixed (?) Fixed (long) Fixed (long)
Bolt to Mast Foot (1) 418 mm 420 mm 434mm 455mm
Jib Sheeting Pos. (2) 158 cm 162 cm 151 cm 158 cm
Jib Sheeting Pos. (3) 90 cm 91 cm 76 cm 92 cm
Mast Rake (4) 112 cm 113 cm 107 cm 102 cm
Mast Rake (5) 116 cm 116 cm 114 cm 106 cm
Shroud Floppiness (6) 0 5 inches 4 inches 2 inches
Shroud Floppiness (7) 4 inches 10 inches 9 inches 7 inches
CB bolt to transom (8) 214 cm 215.5 cm 214 cm 212.5 cm
Spreader Length 320 mm 325 mm
Spreader Deflection 620 end to end 125 aft


Measurements are quite accurate, but should be treated as approximate.  Whilst racing upwind, the mast rests against the aft face of the gate in light winds, and the front face of the gate in strong winds.  The change is caused by the kicker and leech tension bending the mast.

1 Centre of centreboard bolt to aft face of the mast (or extension).

2 Distance from aft edge of transom to bearing surface of jib sheeting block or fairlead

3 Lateral distance between bearing surface of jib sheeting.  This distance is limited in 498, as the boat is narrower than the others and the deck layout is mark 4.

4 Set the end of the main halyard level with the vertical centre of gooseneck.  Swing the main halyard to back of boat and measure from end of the halyard, around the traveller to the underside of the transom.  Ignore the width of the bilge keel.  Perform measurement with jib down and forestay slack.  The mast leant against the back of the mast gate.

5 As above, but the mast held against the front of the mast gate.

6 Lean the mast against the front of the gate, with jib down and forestay slack.  Measure the limit of shroud movement at eye level.  (six foot person, boat on trolley).

7 As above, but the mast leant against the back of the gate.  This measurement is influenced by lateral width of the mast gate.

8 This is the distance from the aft edge of transom to centre of centreboard bolt centre.