F12 CLASS CATAMARAN MEASUREMENT GUIDELINES

Prologue: The Formula 12 class
The Formula 12 catamaran exists with the primary purpose of introducing young, novice and disabled sailors to the thrills of sailing high performance catamarans. With this in mind the following rules endeavor to outline a cost effective, safe and enjoyable class of sailing boat that can also be used for close racing across a range of designs.

The Formula 12 Design Box Rule
1. In case of doubt, the intention of the rule makers, which is referred to as the spirit of the rule, shall take precedence over the letter of the rule. It is the intention of the rule makers to set a reasonably similar drag, relating to a reasonably similar saildrive, resulting in reasonably level performance over many different makes, so as to achieve a fair and effective formula class. For construction, all materials and methods are allowed when these do not imply either an unacceptable risk of bodily harm or the operation of an unseaworthy craft. It is the responsibility of competitors to ensure their craft are safe and seaworthy.

2. A catamaran is defined as a two-hulled sailing boat with essentially duplicate or mirror image hulls, fixed in parallel positions.

3. Sail area shall not be more than: 7.00 square metres. There is no restriction on how sail area is distributed. Sails must be able to be dropped easily in all conditions while on the water or land with mast attached to boat, pocket luff sails may not have sidestays. Where a pocket luff sail is not used, half the mast area shall be included in the total sail area. “The girth measurement shall be taken as the distance from the centreline round the surface of the spar to the same point on the centreline. The resultant dimension shall be divided by two to give the half girth measurement.”
Boom measurement is only included in the sail area if the profile height of the boom is more than 1.5 of the width and shall be taken as per mast measurement.
When undertaking the sail measurement the following points should be noted.
Sail to be measured on a flat surface and laid out in terms of IYRU Measurement & Calculation of Sail Area Instructions. i.e.
“With battens set in their pockets the sail shall be pegged out on a flat surface with just sufficient tension to remove waves or wrinkles from the edge rounds and to spread the sail, as far as possible, substantially flat. Once the sail has been pegged out in this way all the required measurements shall be taken and no alterations to the tensions shall be made.”

4. Mast construction and rigging shall be un-restricted.
A contrasting measurement band shall be located on the mast no higher than 6metres above the top of the front beam. At no time shall any part of the main sail with the exception of a halyard lock or shackle or pocket luff sail cap be located above this measurement band. Unstayed rigs must secure the mast ensuring that during capsize the mast remains attached to the boat.




5. The overall length of the catamaran shall not be more than: 3.80 metres.
The length shall be measured between perpendiculars to the extremities of the hulls with
the catamaran in her normal trim. The measurement shall be taken parallel to the centre
line of the craft and shall exclude rudder hangings, but if the athwartships width of a
rudder within 153mm of the bottom of the hull is more than 76mm, the length shall be taken to the aftermost point of the rudder.

6. The extreme beam width shall not be more than: 2.00 metres
The beam shall be measured at right angles to the centre line of the craft at the widest point and including all fixed or adjustable apparatus, this may be at some point down the sides of the hulls, especially if hulls are angled. It may also be possible that the maximum width is at the bottom of centerboards when fully down.

7. Trapeze is allowed.

8. Each hull shall have at least one inspection hatch.

9. Each hull shall carry at least 30 litres of flotation, which may be provided by solid closed cell foam, solid blocks of compacted foam granulate, air bags or sealed air compartments.

10. The platform shall be equipped with a maximum of two rudders.

11. In addition to the rudders, the platform may also be equipped with one or more daggerboards or centerboards.

12. It is not permitted to adjust the following items while racing: the rake of the mast, the tension of the standing rigging, the angle or length of the spreaders (if fitted).

13. It is the responsibility of the crew to ensure that the boat is equipped with a righting system that will enable the crew to right the boat without any outside assistance.

14. The Formula 12 Class authority may demand that a crew demonstrate their ability to right their boat, but only at a time when doing so does not directly affect the fairness of racing.

15. There will be no other restrictions on crew weight apart from the requirement that the crew weight must be sufficient to right the boat unaided under all encountered sailing conditions.

16. The F12 Division emblem shall be carried on the mainsail over national letters and sail numbers, Sail numbers shall be allotted by the Class Association.

17. Hydrofoils are not permitted. At least one hull shall be in the water while sailing. To this end, centreboards and rudders are to be essentially straight with a maximum camber (top to bottom) of no more than 25mm. They are to be essentially vertical with the distance between the bottom of the boards, when both are deployed, within 100mm of the distance between the top of the boards in the same position.

18. Minimum weight in full sailing trim shall be not less than 50 kilograms. The boat must be weighed in a dry condition and any weights attached to bring the boat to a minimum weight of 50 kilograms must be permanently affixed.

Class administration
19.1. Voting rights
Voting rights are only available to people that have designed, built or currently own a dedicated F12 catamaran. Whilst other designs that come within the rules are most welcome to compete in F12 races they have no voting rights regarding F12 design.
The following people are each entitled to one vote on class matters.
o Designers who have provided a free design of a dedicated F12 for others of which at least one has been built.
o Builders who have built at least one dedicated F12 boat ready to sail.
o Owners of a ready to sail dedicated F12 cat
19.2.a Changing of rules
A change to these rules requires affirmative votes from 2/3 of all people entitled to vote at the time of the poll.
19.2.b Rule changes may not preclude from competition or grandfather currently sailed dedicated F12 catamarans.
19.3. Applicability of rules
These rules exist as a draft only until being ratified or changed by vote after the launch of the 10th dedicated Formula 12 catamaran.
19.4.a. Governing body
Initially the Formula 12 catamaran class shall be run with all those entitled to vote having equal voting rights. Upon the launch and measurement of the 49th vessel the class association may with a 2/3 majority vote choose to implement a governing council which will be empowered to handle the general running of the class.
19.4.b. Where a governing council is adopted they may not make changes to the measurement box rule or voting structure, with out first receiving 2/3 majority support for any changes.
_________________________

The rules are fine. Only one small detail: to avoid an apparent contradiction and to agree with the rest of the paragraph, the quoted sentence should be modified to include those who own an F12:

19.1. Voting rights
Voting rights are only available to people that have designed, built or currently own a dedicated F12 catamaran.

Good point, I modified it.
regards

Good job Jeff. I've sent Mary a PM asking her to pin this thread at the top of the page.

Dear Sir, the publicity for the vuuduu f12 has been great and this office has been asked to do a cnc kitset version for some local kids (and one suspects adults .

We have just been looking over the rules and notice something that seems a little odd compared to other rules, that being that rig hieght is taken from the top of the beam.

Our office has some experience with both the americas cup rule (s) and the 8.5 m rule currently in favour here in NZ and both these air draft rules are measured from the water not the beam mainly to stop hugely distorted main beams.

I would ask those involved to seriousily have alook at this part of what is otherwise a great class and rule


John

Great point John, I wouldn't like to restrict hull volume by measuring from the water. I took those rules from the A Class and they don't seem to have an issue with the interpretation. Would limiting it to straight main beam be reasonable? Would a curved beam make any difference given that the sail is limited?

John the air draft rule is typical of large cat classes, however the rule as it is written here is basically the same as the A class, F16, F18 and other similar classes. It is also attractive as it allows easy measurement on the beach.

I don't see any good reason to amend the rules and I certainly wouldn't vote to change it and if the beam was higher on one design than the other then it only lowers performance as the CG and COA goes higher and the RM comes down

Hi guys thanks for the quick replies. the reason all the major classes have black bands is that they have found that the higher up you push the sail the more power you get thus it would be easier to fly a hull and so on.

In classes such as the 470 etc we have found that even 10mm above black band results in huge gains especially in powering up conditions and downwind.

I'm sure the northland boys dont want to change thier boats with the curved beams so i understand not wanting to change the rule.

I would suggest a definition for the beam from a straight line between beam ends with beam ends on the top of the faired topside line again to stop ugly really high beam mounts, easy enough to put a string line between the highest point on each hull on the beach ???

dont get me wrong i like the beams on the northland boats but do you really want ugly distorted boats or sweet looking rockets that attract top class sailors

We have moved back to NZ and are located in Snells beach just north of auckland and are presently trying to help the local kids get out on the water and have been working on a kitset cat for the juniors to blat around in for a while and this class seems perfect i congratulate graham and billy for taking the initiative and richard for producing a great little design

John

JMO - well done to you and your club, these boats will definitely get kids out sailing. But, I'm not sure that any beach cat classes use an air draft rule. I guess there just isn't much advantage in distorting the beams and you can fly the hull anyway via the wild thing etc. Although, most development classes now have pretty high freeboard and high beams, but mainly to avoid being knocked back by waves. Good luck - I hope you post some updates on the project.

The rules are very clear and can be easily understood. Need details regarding the design of F12.Help is appreciated.