2013 changes are highlighted by this background colour.
2012 changes are highlighted by this background colour.
These regulations are published under the authority of the ISAF.
A.2 Official language
The official language of these regulations is English. In the event of a dispute, the English text shall prevail over any translation.
The word shall is mandatory and the word may is permissive.
The ISAF has the right to amend these regulations if necessary.
Any interpretations shall be made by the ISAF.
A.5 Spirit of the regulations
In case of doubt about any part of these regulations, the meaning, i.e. the spirit of the regulations governs.
Notwithstanding anything contained in these regulations, the ISAF or a National Authority shall have the power to refuse to grant, or withdraw, the status of recognized Class or a rating certificate from any Multihull, giving reasons in writing for taking such action.
The ISAF does not accept any legal responsibility in respect of these regulations.
B.1 Quality of boats
These rules are created mainly for production boats.
Non-productions catamarans, experimental boats and new types with provisional rating may be ranked apart.
B.1.1 Production boats
A production boat belongs to a registered class or to a registered type.
The qualification of registered class or registered type requires the following conditions:
- 1. To respect the safety requirements of the government having jurisdiction;
- 2. To produce a minimum of 10 boats;
- 3. To have published class rules (effective for new types after 01/06/2001) which include data as follows:
- WS - Minimum sailing weight.
- CM - Maximum mainsail area.
- VLM - Maximum VLM.
- CJ - Maximum Jib Area.
- VLJ - Maximum VLJ.
- CSPI - Maximum Spinnaker area.
- LB - Length of Centre or Dagger board below the hull.
- BEAM - The maximum beam of the boat.
- NUMTRAP - The number of crew using trapeze.
- LTM - Length of the Top of the Mainsail.
- 4. To present the boat in a boatshow.
- 5. To present the boat at the nautical press.
B.1.2 Non-production or experimental boats
A non-production boat is any boat which does not belong to a registered class or to a registered type. A boat built as a registered boat but which is modified in such way that she contravenes her class rules will be considered as a non-production boat.
B.2 Rating certificate
To be permitted to race, a boat shall provide a rating certificate issued by the ISAF or a National Authority.
The certificate will state the rating as well as relevant datas concerning the boat and the owner.
The rating certificate is obtained as follows:
- The owner shall have a certificate of origin or a measurement form completed by a recognized measurer.
- The owner applies to the appropriate National Authority for a rating certificate.
- The Rating Certificate is not invalidated by change of ownership, providing the data remains constant.
N.B. A National Authority may require a fee.
Ratings, (i.e. time dividing factors,) take as basis measurable datas, warranted by classes, builders or importers, and are calculated using the IOMR formulas described as follows, verifiable by anyone.
The inputs to the formula are as follows:
- WC Weight of the crew (for calculation purposes only).
- WS Minimum weight of the catamaran in sailing conditions.
- AL Maximum overall length.
- WL Maximum waterline length (before Jan 1st 2007).
- CM Maximum authorised mainsail area.
- VLM Maximum vertical projection of the luff of the mainsail.
- CJ Maximum authorised jib area.
- VLJ Maximum vertical projection of the luff of the jib.
- CSPI Maximum authorised spinnaker area.
- LB Maximum Length of Centre or Dagger board below the hull.
- BEAM Maximum beam of the boat.
- NUMTRAP Maximum number of crew using trapeze.
- LTM Length of the Top of the Mainsail.
- B2007 apply Rated Length adjustment.
- SH apply Sinking Hull adjustment.
- LF apply Lift Generating Foils adjustment.
All the following formula use metric units.
C.3.1 Rated Measurements
- Rated Length L
- Rated Length, after Jan 1st 2007, L = AL
- Rated Length, before Jan 1st 2007, L = WL + 0.1 x (AL - WL)
- Rated Weight W = WS + WC
- Rated Sail Area A = M + J
- Rated mainsail Area M = CM x ME
- Mainsail efficiency ME = SE %
- Rated Jib Area J
- Multihulls without spinnaker J = CJ x JE
- Multihulls with spinnaker J = ((CJ x JE)/100) + (CSPI * 0.1)
- Jib efficiency JE = SE %
- Square Top Mainsail Adjustment
- Mainsail efficiency ME = SE x CTMS
- CTMS = (1 - (0.12538 - RTMS))0.8
- RTMS = ((LTM x VLM) / 4) / CM
- Sail efficiency SE
- Sail efficiency SE = 40.1 + (18.31 x X) - (2.016 x X2) + (0.07472 x X3)
- where X is the respective sail aspect ratio, as shown below
- Mainsail Aspect ratio XM = VLM2 / CM
- Jib Aspect ratio XJ = VLJ2 / CJ
C.3.2 Intermediate calculations
- ZM2 = √(W x L) / A
- DLR = W / L3
- XC4 = 1.0 + (0.0061012 x ZM2 x L x DLR)
- XC2 = 0.4556343 - (0.473292 x ZM2 x (1.038881 + (0.4371713 x DLR)))
- XC = (-0.0414213 - (2.554547 x (ZM2/L))) + (0.00132305 x ZM2 x L2))
- VTVB = √(-XC2 + √(XC22 - 4 x XC4 x XC)/2 x XC4)
C.3.3 Corrections and Penalties
- Lift Generating Foil is: LGF = 1.15
- and is the adjustment applied, for specific classes to the Board Correction.
- Board Correction is: BC = 0.01 + LB / 35 x LGF
- Sinking Hull adjustment is: SH = 1.0088 and is the adjustment applied, for specific classes on the final Rating.
C.3.4 Power Factor
- The Power Factor (PF) takes into account the Heeling (HM) and Righting moments (RM) as follows:
- Power Factor PF = 0.0527 x (HM / RM)2 - (0.0602 x HM / RM) + 1.0147
- Power Factor is subject to a maximum of 1.036
- Heeling Moment HM = ((0.42 x (VLM + 1) x CM) + (0.33 x (VLJ + 1) x CJ)) x 9.7037
- Righting Moment RM = (0.5 x BEAM x WS) + (BEAM x CW x 75) + (0.93 x NUMTRAP x 75)
C.3.5 Rating (or Time Dividing Factor)
- R = 0.8 x PF x (VTVB) x (1 - BC) x 0.995 x SH
- where the final rating will be calculated to 3 decimal places and where SH is the Sinking Hull adjustment applied to specific classes.
All measurements must be undertaken according to the ISAF measurement rules and instructions.
For "Formula" type classes such as Formula 18 and A-Class, the rating is to reflect the limiting values for all relevant measurements permitted by the class rules. Where a measurement is required by SCHRS but not governed by class rules it is necessary to carry out measurement as required for an SCHRS rating.
D.1 WC : Weight of the crew
The weight per crew member is assumed to vary according to the length of the boat, the sail area and the number of crew according to the following formula:
WC = 70kg + Rated Length (L) in excess of 5m x 10 capped at 80kg + an extra 3kg for single handers for each square meter of Rated Sail Area (A) in excess of 13m, capped at 10kg.
D.2 WS : Minimum weight of the catamaran in sailing conditions
- The sailing weight is the weight of the catamaran ready to sail, excluding personal equipment, such as buoyancy aids or trapeze harnesses.
- The boat itself, and all gear and sails weighed, should be in a dry condition. If this is not possible every effort should be made to dry the items as much as possible, and then the measurer should apply a correction for the weight of the remaining water.
- All "normal" and "reasonably sized" sheets and lines used for sailing are to be included, if always carried.
- Paddles are to be included, if always carried.
- Other items, if always carried, will be included, or a fraction of the weight thereof included, in the WS measurement at the discretion of the measurer, who will also decide what is "normal" and "reasonably sized"
- A maximum of 10kg of corrector weights, in accordance to the class rules if applicable, may be used to bring the weight up to the WS.
D.3 AL : Maximum Overall Length
The horizontal distance between the forwardmost point on the hull proper, to the aftmost point on the hull proper (normal rudder fittings to be excluded).
D.4 WL : Maximum Waterline Length (before Jan 1st 2007)
To be measured with the boat at sailing weight WS plus crew weight WC. For transom sterned boats, the added weight WC will be distributed until both transoms just touch the water. Other boats will be measured with the weight distributed so that the waterline is parallel to the sailing weight waterline.
D.5 CM : Maximum Authorized Mainsail Area
Maximum mainsail area allowed by the class rules or, in default, registered by the builder. CM includes spars, if mast rotates. (ISAF measurement rules and instructions).
D.6 VLM : Maximium Vertical projection of the Luff of the Mainsail
To be measured along the aft side of the mast, between two bands. When sailed, the mainsail head shall not be hoisted higher than the bottom of the upper band, and the tack point shall not be downhauled lower than the top of the bottom band. For classes or types which have no requirement in their class rules for a lower black band, the VLM will be measured by hoisting the sail and downhauling it just enough to take out any creases, and then measuring the sail from the top of the headboard to a point on the aft side of the mast which is at right angles to the lowest part of the sail.
D.7 CJ : Maximum authorized Jib Area
Maximum Jib area allowed by the class rules or, in default, registered builder.
D.8 VLJ : Maximum Vertical projection of the Luff of the Jib
To be measured along the forward side of the mast. Where this is time consuming the measurer may use an approximation as follows:
VLJ = LJ x 0.95 (where LJ is the length of the Luff).
D.9 CSPI : Maximum authorized Spinnaker area
Asymetric spinnakers are allowed.
The half width, i.e. the distance between the half leech points shall be greater or equal to 75% of the foot length.
CSPI = SF x ((SL1 + SL2) / 4) + (SMG - (SF / 2)) x 2/3((SL1 + SL2) / 2)
Where SF = foot; SL1 = luff; SL2 = leech; SMG = half width
Stiffening devices such as headboards and battens are prohibited.
IYRR 50.2 does not apply.
Where a spinaker has an SMG measurement which falls short of 75% of SF, CSPI shall be incresed according to the following formula:
CSPI = CSPI x (1 + (( 0.75 - SMG/SF) x 2))
and any headsail capable of effective use upwind shall be rated as a jib.
D.10 LB : Maximum Length of Centre or Dagger board below the hull.
For the standard daggerboard this is the length of the board below the hull. For T Foil this is the combined vertical and horizontal measurements. For curved daggerboards this is the measurment around the external circumference of the board.
D.11 BEAM : Maximum beam of the boat
The maximum width of the boat, including wings, racks, sliding seats or other appendages.
D.12 NUMTRAP : Maximum number of crew on trapeze
The maximum number of crew on trapeze
D.13 B2007 : Rated Length adjustment
Measurers should enter B in this box for designs established before 1st January 2007. The calculation of rated length takes into account the waterline length of older boats (WL) as well as the overall length (AL).
D.14 LTM : Length of the Top of the Mainsail
For square headed mainsails, the horizontal length of the top of the mainsail is measured in accordance with the diagrams. Square headed mainsails are those where the angle between the mast and the top of the sail exceeds 55 degrees.
D.15 SH : Sinking Hull adjustment
Measurers should only apply the Sinking Hull adjustment to deep V hulls such as those on the Hobie 14 and Hobie 16.
D.16 LF : Lift Generating Foils adjustment
Measurers should only apply the Lift Generating Foils adjustment where the class is considered to have lift generating foils.
E. RACING RESULTS
E.1 Corrected time
The racing results are calculated by dividing the sailing time by the rating (or time dividing factor) to obtain corrected time.
E.2 One-design classes and subgroups
As mentioned in the preamble, National Authorities or organisers may consider separate arrangements or rankings with one-design or level rating classes or subgroups present in sufficient numbers.
E.3 Non-production or experimental boats
Non-production or experimental boats may be ranked apart.
E.4 Boats sailing under provisional rating
Boats sailing under provisional rating may be ranked apart.
Ratings are assigned by the ISAF, according to the report of the measurer officially recognised by the ISAF or a National Authority.
F.2 Existing types
For existing types which comply with the production boat qualifications, classes and builders shall register each type a standard form giving the data mentioned at paragraph C.2. The ISAF will assign for each a rating which will be valid from the first of January each year.
F.3 Approval of a new type
To get a rating for a new type, a class or builder shall register a standard form giving the data mentioned in paragraph C.2., so that the ISAF can compute a provisional rating.
The ISAF will send the class or builder measurement forms in sufficient number.
As soon as the conditions required to be considered as a production boat are completed (see paragraph B.1.1.), the ISAF may publish a list of updates which become effective on the date of issue unless otherwise stated.
Each year, after the November meeting of the ISAF, it will issue a list of ratings which will be valid from the 1st of January of the following year, unless otherwise prescribed by the ISAF or a National Authority.
During the year, the ISAF may publish lists of updates which will become effective at the date of issue unless otherwise stated.
G.2 Builders liability
It is the builder's or his representative's inescapable responsibility to ensure that his hulls, spars, sails, foils and equipment comply with the class rules and these rules at the time of delivery and that alterations to the product are registered with the ISAF before being produced.
When dimensions of a design are found to differ substantially form the original measurements, the ISAF can decide to alter the original rating to a more penalising one.
Deviation from the maximum and minimum dimensions in one or other direction from the data given on the official lists will never lead to a change to a less penalising rating.
If a class has a rule change or any development which may influence the SCHRS rating then its rating is to be recalculated on the new basis and the number published as appropriate.
G.4 Provisional ratings
Provisional ratings are assigned by the ISAF (see paragraph E.3.).
H.1 Inspection or measurement during a regatta
A race committee or a National Authority has the right to conduct an inspection or a measurement during a regatta to check the compliance with the class rules and with these rules.
H.2 Identification marks
Catamarans of recognised classes or registered types shall carry identification marks, indicating the type of catamaran on hulls and sails.
H.3 Responsibility of the owner or his representative
It is the owner's or his representative's inescapable responsibility to ensure that his hulls, spars, sails, foils and equipment comply with the rules of the class in which he enters and these rules at all times, and that alterations, replacements or repairs to the hulls, spars, sails, foils and equipment do not contravene the class rules and these rules and are reported to the measurement form.
New or altered sails shall be measured by a measurer who shall mark the sail near the tack. The National Class Association or the National Authority shall issue a new certificate.
It is the owners or his representative's responsibility to ensure that their boat conforms to the current rating certificate.
H.4 Rule compliance
In case of a measurement dispute in respect of hulls, spars, foils, sails, battens, type of fittings or equipment and the placing of the same if controlled by these regulations, the following procedures shall be adopted:
- A sample of ten boats of the same class shall be taken at random and measured by the same identical techniques.
- The dimensions of the disputed boat shall be equal to, or between the maximum and minimum dimensions obtained from the ten sample boats.
- If the protested boat is outside these dimensions, the matter, together with any relevant information shall be referred to the chief measurer of the National Authority under whose jurisdiction the race takes place, who shall give a ruling.
H.5 Responsibility of the measurer
A measurer shall not measure hulls, spars, sails, foils or equipment built by himself, or in which he is an interested party or has a vested interest.