International Moth Class Association Measurement Manual

1

st Edition: John Butler, September 1984

2nd

Edition: Ian Ward, June 1994 3

rd Edition: Rohan Veal and Mark Robinson, May 2004

4th Edition: Adam May, Aug 2009

CONTENTS 1. Authority 2. Introduction 3. The Role and Responsibilities of the Measurer 4. Measurement Equipment 5. International Moth Class Rules 6. Measurement Forms 7. Hull Measurement 8. Measurement of Spars 9. Sail Measurement 10. Endorsement of Certificates and Maintenance Measurement 11. Measurement at Championships 12. Training and Examination of New Measurers 1. AUTHORITY

This manual obtains it authority within the International Moth Class from the IMCA Council of Presidents. It may be amended from time to time as required, with immediate effect, by the IMCA Executive Committee, provided subsequent approval is granted by the Council of Presidents at the next held IMCA AGM. 2. INTRODUCTION

The purpose of this manual is to provide a consensus opinion of the acceptable approach to measurement of International Moth Class sailing dinghies. The Class Association aims to encourage a consistent and professional approach to measurement from its totally volunteer team of measurers. It is important to stress that this manual is supplementary to the International Moth Class Association (IMCA) rules, and does not replace the the International Moth Class Association rules. 3. THE ROLE AND RESPONSIBILITIES OF THE MEASURER

It is the responsibility of the Measurer to ensure that an International Moth which has been measured and subsequently certified by the National Association, has undergone proper and accurate measurement in accordance with the spirit and letter of the rules of the International Moth Class. A measurer shall not measure any boat in which he has a personal interest, ie, financial involvement, helmsman, owner, builder, designer, etc., however 'personal' or 'financial' involvement does not include the measurer's task of measurement or his fee for that measurement, if applicable. It is the duty of a Measurer, when completing a measurement form, to record only FACTS.

Measurers, in their own interests, shall not enter into any debate as to rule compliance of a particular boat. Any queries or deviations from normal should be noted on the form under 'Measurer's Remarks', and the IMCA requested to obtain a definitive ruling. The IMCA can issue a Temporary Certificate, conditional upon the correct interpretation of a particular deviation, which may be withdrawn at any time. If a measurer is in doubt as to whether the boat complies with the 'Spirit' rather than the letter of the rules, suitable notes shall be made on the Measurement Form, or attach sketches, etc. 4. MEASUREMENT EQUIPMENT

Measurers are expected to provide their own equipment, and are therefore recommended to prepare a measurement kit consisting of the following:

The International Moth Class Rules.

IMCA Measurement Manual.

IMCA Measurement Forms.

Measurement and Calculation of Sail Area document.

I.S.A.F. Racing Rules of Sailing.

I.S.A.F. Equipment Rules of Sailing.

A 10 metre steel tape, 3 metre steel tape and a steel ruler; all graduated in millimetres.

Spirit level, Plumb Bob and 5 metres of clear bore plastic tubing.

A large 90° set square or draughtsman's T square, Ring or template.

A 90mm internal diameter ring.

A reel of whipping twine or heavy duty fishing line.

Indelible ink marker pen, notepad, clipboard and ball point pen.

Purpose built Measurement Calliper or frame for accurate measurement of overall length and width

IMCA Measurers stamp 5. INTERNATIONAL MOTH CLASS RULES

The latest copy of the International Moth Class Rules are kept on the IMCA World Website, along with the latest copy of the measurement form & certificate document. The sail area calculation spreadsheet can also be downloaded from the „Rules & Documents‟ section of the website. http://www.moth-sailing.org/imca/faces/Rules_Docs.jsp The International Moth Class is a development boat class where boats are built to class rules which set limits on only a few certain parameters (like length, beam & sail area), and development of any ideas within these parameters is encouraged. As a result there are considerably fewer measurements to be taken on a than on a one-design class, and the measurers should assume that anything which is not specifically prohibited is permitted. If a measurer has any doubts about the legality of any item he should report the matter to the IMCA for advice. As a result of such feedback from the measurers, lessons can be learnt and rules can be regularly updated and improved for the future. A good measurer should report ideas and errors found in rules, remembering that he is part of a team of administrators who are effectively the guardians of the rules.

6. MEASUREMENT FORM & CERTIFICATE

The International Moth Class Measurement Form and Certificate are one document comprising three parts, namely:

6.1 Part 1 – Owners Details

This is a record of the owners details, the owner declaration and national Authority endorsement.

6.2 Part 2 – Measurement Form

MMeasurements taken and compliance with rules in respect of hull, mast and sails, complete with the Measurer's Declaration.

PPaarrtt 11 –– OOwwnneerrss DDeettaaiillss && PPaarrtt 22 –– MMeeaassuurreemmeenntt FFoorrmm

6.3 Part 3 – Sail Area Measurement Form

The sail area measurement form, with one page for each sail. Additional pages are to be added as necessary.

PPaarrtt 33 –– SSaaiill AArreeaa MMeeaassuurreemmeenntt

The actual form is an „Excel‟ spreadsheet used to perform the actual calculation of area based on the dividing up of the sail into lots of separate triangles or fair curved portions. The boat owner should be presented with a printed out copy of the filled in spreadsheet, or a paper copy filled in during the sail measurement. 7. HULL MEASUREMENT

7.1 Preparation

Firstly, the measurer should ascertain that the boat presented for measurement is in its as-sailed condition, ie, wings with dihedral are attached and set to the position and angle encountered when sailing, and if this is not apparent, the disparity is to be noted under Measurer's Comments. Similarly, adjustable gantries must be set to the normal sailing position by the owner, prior to measurement proceeding, and if a number of positions are suggested the full range of variance shall be measured and declared on the measurement form. Should the measurer be in any doubt as to the owner's observance of this procedure then a sailing demonstration should be requested and the observations recorded on the measurement form. Looking at each item within the International Moth Class Rules in turn:

7.2 Overall Length Between Extremities

“6.1 The overall length of the hull, excluding attached rudder fittings and stem fittings shall not exceed 3355 mm measured between perpendiculars with hull level transversely and waterline horizontal.” “6.1.ii – Any fittings or fairings attached to the hull, except for the stem and rudder fittings shall be considered part of the hull.”

Relevant definitions: Hull - Includes a single buoyant hull, wings, racks, which must be rigidly connected while racing. Excludes rudder, rudder fittings, centreboard, and other foils. Rudder Fittings- Non buoyant structure used solely to support the rudder. Stem Fittings - A device to connect an object pertaining to rig or foils to the hull. Static Waterplane - The plane containing the static waterline of the hull is determined with the boat fully equipped, afloat and upright without crew. Winged or flexible transoms will be measured in the raised positions. Any cross section shall be taken perpendicular to the hull.

With most modern Moths being of a low rocker, vertical stem and transom design, it is often sufficient to measure the hull length with a tape measure along the keel line of the hull. Should the hull not measure under this method (due to slight curvature in the tape), or the hull is of a differing shape, the calliper or frame system shall be used. Measurement shall be along the horizontal waterline, exclusive of rudder and stem fittings, by the use of a calliper or frame. The measurer is to ensure by the use of a plumb line or 90° square that there is no projection, other than stem or rudder fittings, beyond the perpendiculars at either end, eg:

MMeeaassuurreemmeenntt ccaalliippeerr ppllaacceedd oovveerr aann uuppttuurrnneedd hhuullll..

WWaatteerrlliinnee

OOvveerraallll lleennggtthh

Should the waterline not be readily apparent then the boat shall be floated in its fully rigged condition, upright, but without crew, and the positions marked at either end. The extremities are measured perpendicular to the projection of this waterline at either end. The suggested measurement method utilising a measuring frame is as follows:Due to callipers varying in length according to their materials of construction, ambient ttemperature, etc., the overall dimension between uprights, (Dimension 'A') can be measured using a steel tape at the precise moment of measurement. With the calliper in place over the hull, measuring back from one end using a steel rule will give Dimension 'B'. Subtracting Dimension 'B' from Dimension 'A' will give the overall length, eg, Dimension 'A' (3380mm) minus Dimension 'B' (27mm) = 3353mm.

Points to note with Scow type Moths in particular, are that asymmetrical bows and transoms shall be measured to their extremities.

DDiimmeennssiioonn BB

This is also applicable to rear wingbars that are mounted close to the transom. The measurement rules refer only to maximum length and beam of the hull. No reference is made to the form or type of construction. Hence 'wings' are considered to be an integral part of the hull and are typically only detachable for the purpose of transport. Note regarding rudder gantries: The topic of the removal of fixed rudder fittings and gantries, was raised at the 2005 EGM. The Committee felt that the rudder fittings and/or gantries do not need to be readily removable from the hull (i.e. can be bolted or glued on) but should not be made as part of the moulding process of the hull, and should comply with the current rules regarding extension of the waterline and fairing into the hull. Many modern boats have a bolt or carbon tang bonded into the hull after the hull is constructed for the attachment of the lower gantry leg. Many older boats had a gantry permanently bonded in place, and the above ruling was made to ensure that these were not judge as out of class.

7.3 Rudder & Stem Fittings

““No attempt at increasing waterline length shall be made by fairings comprising part of, or attached to rudder or stem fittings.””

Relevant definitions: Rudder Fittings- Non buoyant structure used solely to support the rudder. Stem Fittings - A device to connect an object pertaining to rig or foils to the hull.

A rudder, fixtures and external rudder supports are allowed, provided that no attempt are made to increase the effective sailing waterline length. Below is an example of a rudder stock that is faired into the hull, and is not permitted.

Below are shown some examples of modern gantries. Many gantries often feature flat panels to reduce their drag when immersed. Care must be made to ensure there is sufficient gap between the hull and this structure to not be considered a fairing.

While some of these may be considered as drag reducing fairings, they are not extending the waterline length. The static waterline plane is defined within the rule, but for the purpose of this rule it may be necessary to consider the waterline of the boat with the helm onboad, for if a performance advantage is being sort it would be of most relevance in sailing trim. If the measurer considers that the rudder gantry does in fact fit within close proximity of the hull in such a fashion as to present a near smooth, even or regular transition onto the gantry surface Example case study: The pictures over the page show the same gantry design attached to two different hull designs. On the left there is a clear step in the transition from hull to gantry all the way around the hull, whereas in the picture on the right, the gantry fits neatly with the hull lines. While there is a small gap between the hull and gantry structure this would be considered to present a fairing that extends the waterline length of the hull and would not be permitted. [The gantry in question was amended to a tubular design shortly after it was fitted on realisation that this was pushing the rule too far]

Within the definitions, the term non buoyant is used, yet many gantries would actually float if tested because they are made up of sealed hollow carbon tubes, or from carbon and foam panels. This is deemed acceptable as long as the design of the gantry does not start to utilise this structure as a bouyant element within the boat system. For example, bouyant rudder gantry structures like those used on many modern International 14‟s to give some reserve bouyancy whilst tacking are not permitted.

7.4 Stem & Rudder Fittings 500mm Rule

“If the stem or rudder fittings extend more than 500mm beyond the limits of the overall length, of the hull, the excess shall be added to the measured length of the hull.” Relevant definitions: Rudder Fittings- Non buoyant structure used solely to support the rudder. Stem Fittings - A device to connect an object pertaining to rig or foils to the hull.

The length of any rudder or stem fitting is restricted so that the boats do not become excessively long. Rudder gantries have grown with the use of hydrofoils, but the permitted length was also applicable to stem fittings so as to not limit the possible development of different foil configurations, and rig attachment options.

500mm permitted extensions before excess is added to measured hull length.

For example if the measured hull length was 3350mm, and a gantry was measured to be 505mm the total measured length would be: 3350 + (505-500) = 3355 A stem fitting could be 500mm from the bow, and a rudder fitting 500mm from the transom before any excess is added to the measured length of the hull. The rule is not intended to limit the extension to only one or the other. The measurer should ensure that fittings are set in their normal sailing positions by the owner, prior to measurement proceeding. If the item is adjustable and can assume a number of positions the full range of variance shall be measured and declared on the measurement form. It is not just rudder gantries that must be checked under this rule, many of the surface sensing „wand‟ systems in use with hydrofoils are mounted near the stem, and as they are a foil related item that is connected to the hull they are bound by this rule.

Many of the sensor „wands‟ used on hydrofoil equiped Moths are mounted in such a way that they project forward of the stem in their two most extreme settings. This projection forward may need to be measured if no stop system is in place.

7.5 Overall Beam

“6.2 The overall beam shall not exceed 2250 mm.” „Wings‟ are considered to be an integral part of the hull and thus the overall beam shall include them. Principles of measurement are similar to those with overall length, although the use of callipers is not normally required, as it is often easier to get a straight measurement with a tape measure. Where wings are encountered, the outer projection of any material, including trampoline cloth, foam or air bags, should be measured, not purely the structural element.

OOvveerraallll BBeeaamm

If flexible wings extend the overall width when bent, this should be taken into consideration, eg,

Remember to press down on both wings simultaneously when measuring, whether the wings appear flexible or not, and check for the maximum dimension at both ends as well as the middle of the tube. Please note that there is no stipulation as to maximum distances from the centreline, so asymmetrical hulls are not penalised.

It is common practice now to attach a form of protection on the outer edges of the wing frame to prevent the stratching and wear of carbon tubes in particular. It is not the intention of this rule to limit these attachments as long as they serve no other purpose than to protect the wingbars. All items relevant to the performance of the boat shall be measured; ie the trampoline material and rope wrap around for the rear support strop are required performance items and shall be included.

7.6 Longitudinal Air Gap

“6.3i, There shall be no visible air gap dividing the boat longitudinally throughout its length when viewed from fore or aft.”

This generally only applies to scow type Moths in order to restrict the possibility of producing a multi-hull configuration. The air gap can normally be ascertained by visual inspection using a long straight-edge spanning the 'tunnel'. If a 'tunnel' underwater shape is continuous almost to the transom, this can only be tested by a flotation test as described in Rule 6.3 (i).

AAnn eexxaammppllee ooff aa ttuunnnneell hhuullll tthhaatt wwoouulldd bbee iilllleeggaall uunnddeerr mmootthh ccllaassss rruulleess

Questions are often raised regarding wing bouyancy. A vote and poll of the member associations during 2002 and a decision made by the IMCA Executive, decided that the use of wing buoyancy is appropriate so long as the moth is not sailed as a multihull. It was also decided that wing mounted hydrofoils provided multihull like stability and were to be in breach of the no multihull rule. The following interpretation was issued to allow use of the existing rules to enforce this decision. Wing Buoyancy - There is no limitation to the amount, type or shape of buoyancy contained in the wings, trampolines or wing tubes of an International Moth (other than that defined in rule 6.3.i), however the boat must NOT be sailed with the wing bar floatation on the waters surface for more than is required to stabilise the boat back to a vertical position, otherwise this is in breach of rule 6.3.i.

7.6 Hollow in the Hull

“6.3ii. Below the static waterline and within the overall length of the hull, there shall be no hollow in the hull more than 75 mm in any section closer than 2700 mm from the aft perpendicular as described in rule 6.1. The reference line for this hollow shall be a string line stretched tightly around the underside of the hull from points on the static waterline either side of the hull” Relevant definitions: Static Waterplane - The plane containing the static waterline of the hull is determined with the boat fully equipped, afloat and upright without crew. Winged or flexible transoms will be measured in the raised positions. Any cross section shall be taken perpendicular to the hull. Hull - Includes a single buoyant hull, wings, racks, which must be rigidly connected while racing. Excludes rudder, rudder fittings, centreboard, and other foils.

The intent of this rule is to provide a restriction on scows becoming catamarans. It also applies to all other hull designs. The hollow measurement is made with reference to a taught stringline from the waterline on one side, under the hull to the waterline on the other side. It is measured transverse to the hull, to a point 2700mm from the transom. Forward of that point no restrictions apply. Two catamaran bows are allowed.

7.7 Foil Protrusion

“6.3iii - Any fin or foil, excluding the rudder, shall protrude out of the hull from below the static waterplane.” This applies to all centerboards, lee boards, foils, wings, hulls and floats installed as for racing. A vote and poll of the member associations during 2002 and a decision made by the IMCA Executive, decided that wing mounted hydrofoils provided multihull like stability and were to be in breach of the no multihull rule. [ IMCA rule 11.2] The following interpretations were issued to allow use of the existing rules to enforce these decisions.

TThhiiss mmeeaassuurreemmeenntt sshhoouulldd nnoott eexxcceeeedd 7755mmmm iinn tthhee

rreeggiioonn bbeellooww tthhee wwaatteerrlliinnee aafftt ooff tthhee ppllaannee 22770000mmmm

ffrroomm tthhee aafftt ppeerrppeennddiiccuullaarr..

22770000mmmm ffrroomm aafftt ppeerrppeennddiiccuullaarr

Hydrofoils - Wing mounted surfacing piercing hydrofoils are in breach of 6.3.iii. This interpretation is effective as of 1

st December 2003.

Winged centerboards or winged rudders are NOT in breach of any IMCA rules.

EExxaammpplleess ooff wwiinngg mmoouunntteedd ssuurrffaaccee ppiieecciinngg hhyyddrrooffooiillss

7.8 Rule 52

“6.4 – In alteration to RRS 52, only remote controls using stored power are prohibited.”

“RRS 52, Manual power – A boat‟s standing rigging, running rigging, spars, and movable hull appendages shall be adjusted and operated only by manual power.”

Following the adoption of hydrofoils controlled by a surface sensing „wand‟ system the Committee recommended that RRS 52 be amended in the class rules to allow the use of “non-motorised devices” on International Moths. (It was only when the 2005- 2008 Racing Rules of Sailing came into effect that we had the option of changing the class rules to amend RRS 52 under RSS 86.1c) The concequence of this is that the surface sensing wand systems in common use that control a foil or flap angle are not restricted by RRS52.

7.9 Buoyancy

“7.1 - Boats shall have not less than two separate buoyancy tanks or bags attached firmly to the hull which together must be sufficient to float the boat's own weight plus 75 kg, approximately level when capsized or full of water, and which, with any one tank flooded must be sufficient to float the boat's own weight plus 10 kg. If a measurer cannot ascertain compliance with this Rule by visual inspection, they shall undertake a buoyancy test to so satisfy themselves. 7.2 - The measurer shall satisfy himself that the buoyancy compartments are effective by means of flotation or air test. (As a guide, leakage should not exceed 5% of volume of tank in half an hour.)”

There shall be not less than two adequate buoyancy tanks or securely attached bags which by either inspection or flotation testing should be adequate to fulfill the bouyancy requirements decsribed above. It is not always possible to test the capacity of a buoyancy tank. It may be necessary to measure the tank volume by taking the density of water as 1.0. Eg: The volume of a tank 1,000mm x 500mm x 200mm is 100 litres, which should provide approximately 100 Kg of buoyancy. Watertightness within buoyancy tanks can only be fully proved by a capsized buoyancy test. However, a visual inspection can circumvent this if properly carried out. Check for gaps at joints, cracks, proper fitting of inspection covers, bung fittings and rudder pintles, etc. Other items requiring special attention are joints within cockpit wells, and deck/hull joints near the centreboard case and gunwhales. 7.10 ISAF Plaque “5.2 - The ICF plaque shall be fixed to the hull near the transom or on the forward vertical bulkhead . Should this plaque come off or need to be removed at a later date, this shall not invalidate the measurement certificate but the national letters and the ICF Plaque number shall then be permanently engraved on the hull near the transom.” The International Class Fee plaque should be positioned as per the IMCA rules.

In the case of a lost plaque it should be noted that „permanently engraved‟ is meant to mean the carving, cutting or etching onto the surface. Marker pen is not sufficient. Practical solutions that have been seen are the numbers being carved out of a thin piece of wood, and glued onto the hull, or cut out of a thin laminated sheet of glass or carbon fibre and bonded to the hull skin near the transom.

8. MEASUREMENT OF SPARS

8.1 Overall Length

“8.1 - The overall length of mast shall not exceed 6250 mm. The mast should be measured straight unless it is permanently pre-bent. It is not possible to make effective measurements of the mast whilst the sail is rigged.

The overall length of a mast includes sheave blocks at the head, and also the step or socket plug at the foot of the mast. If the mast has a permanent bend Rule H4.1 within the 2009-2012 Equipment Rules of Sailing states: “Measurements in the length direction shall be taken along the spar at the side relevant for the measurement and between sectional planes through the measurement points at 90° to the spar at each point.” If such a spar is measured it should be recorded on the measurement form that it is a pre-bent spar measure in this way. It is recommended to also note the amount of mast curvature on the measurement form.

8.2 Measurement Bands

8.2 - Measurement bands, not less than 15 mm wide shall be marked on the spars so that they are clearly discernible when racing. The inside edges of these band define the limits to which the sail may be set. 8.3 - The distance between the bands shall not exceed 5185 mm. 8.4 - For sails that enclose the mast, an upper measurement band is not required. For the purpose of 8.3, the measurement point for the lower edge of the upper mast band shall be defined as the upper most part of the mast. A minimal amount of webbing or similar, used to secure the head of the sail, shall be disregarded for the purpose of Rule 8.” Measurement bands (limit marks) are required to be marked distinctly (in a colour contrasting sharply with that of the spar) on the mast so as to be clearly visible while racing. The mainsail has to be set within the limits indicated by the inner edges of the bands. Although paint is the most commonly used method of applying bands, durable adhesive plastic tape is now sometimes used and has been approved by the ISAF, provided that the measurement side of the band is permanently marked on the spar by means of punch marks or scribe lines in the surface of the spar. Measurers should note for sails that enclose the mast, upper measurement bands are not required.

8.3 90mm Ring

“9.4 - Only the area of that part of the spars that will not pass through a ring of 90 mm internal diameter shall be included in the overall sail area.” If either the mast or boom (or both) will not pass through a 90 mm ring, those parts exceeding 90mm shall be measured as extra sail area.

A typical example of this might be with a wingmast eg,

This area to be measured.

90 mm

9. SAIL MEASUREMENT

The intention is to establish a reliable and simple method of measuring the whole driving area of the sail plan, including the spars when required. It is not possible to frame methods to deal with every eventuality and therefore in the case of unique or difficult shape of rig, the measurer may need to use his judgement in dividing the rig for measurement in order to calculate the area accurately. It is important to note that the International Moth Class does not have sail design restrictions like other classes; in particular:

Moth sails are not subject to restrictions on materials, thickness or reinforcements, including the use of wingsails.

Sleeve luff sails have special allowances.

Spars are included in the sail area measurement where they exceed 90mm diameter (ie. wing masts).

Prior to setting out the sail for measurement of area it is important that the following essential criteria have been satisfied.

9.1 Emblem

“5.1 - The class emblem shall be a representation of a Moth and shall conform in shape and size to the pattern held by the ISAF. Copies may be obtained from IMCA or National Authority or its delegated representative (National Association).” The International Moth Class emblem shall conform to the shape held in template form by the IMCA , which is available in a number of electronic formats on the IMCA website. Emblems can be affixed back to back on either side of the sail but must be solid, and not in outline only. There are no colour restrictions on the emblem, and it does not need to be the same coulour as the country code and sail number.

The exact dimensions of the emblem are shown below:

9.2 Identification Marks

The International Moth rules state: “5.3 - The sail number, national letters and class emblem on the sail shall conform with ISAF RRS Appendix G. Letters and numbers shall not be less than the following sizes: Height 250 mm Width 150 mm (excluding „1‟ and letter „I‟) Thickness 35 mm Space between adjoining letters and numbers 50 mm 5.4 - All emblems, numbers and letters shall be of durable material and securely attached” The relevant sections of ISAF RRS Appendix G (2009-2012) are: G1.2 Specifications (a) National letters and sail numbers shall be in capital letters and Arabic numerals, clearly legible and of the same colour. Commercially available typefaces giving the same or better legibility

than Helvetica are acceptable. (b) The height of characters and space between adjoining characters on the same and opposite sides of the sail shall be related to the boat‟s overall length as follows:

Overall length Minimum Height Minimum space between characters

and from edge of sail

Under 3.5m 230 mm 45 mm

3.5 m – 8.5 m 300 mm 60 mm G1.3 Positioning Class insignia, national letters and sail numbers shall be positioned as follows: (a) Class insignia, national letters and sail numbers shall when possible be wholly above an arc whose centre is the head point and whose radius is 60% of the leech length. They shall be placed at different heights on the two sides of the sail, those on the starboard side being uppermost.

(b) The class insignia shall be placed above the national letters. If the class insignia is of such a design that two of them coincide when placed back to back on both sides of the sail, they may be so placed.

((cc)) National letters shall be placed above the sail number.

G5 Changes by Class Rules ISAF classes may change the rules of this appendix provided the changes have first been approved by the ISAF.

With the need to refer to both the International Moth Class Rules and Appendix G of the ISAF Racing Rules of Sailing it appears we have a contradiction with both providing measurements for sail numbers and country codes. ISAF RRS Appendix G1.2b defines the height of characters and space between adjoining characters related to a boat‟s overall length, but G5 states that the ISAF classes may change these rules, and thus as the slightly different height and spacing rules defined within the Moth class rules have been approved by ISAF, they are the principle measurements. It should be noted however that the Moth Class Rules do not mention a required spacing between characters and the edge of the sail, and thus for that we must use the measurement provided within G1.2b of 45mm for a boat of overall length less than 3.5m. Overall length shall be taken as hull length (ERS D.3.1).

Below is an example of the Helvetica font type and the required spacings and sizes.

[Note – lack of adherance to these measurements is the most common measurement infringment within the class.] It is becoming more and more common for people to use more „cartoon style‟ fonts for country codes and numbers. These are allowed if thought to give similar legibility to that shown above. If the measurer has any doubts, it should be noted on the measurement form and the IMCA Exec committee should be contacted. Moths are increasingly being sold across borders, traditionally requiring new owners to not only change numbers on the bought sails, but also go through a re-registration process. It is also increasingly difficult to tell how many moths have been sold or are active in the world. From January the 1st 2008 all new moths worldwide carry the same number as their ISAF ICF Plaque as their sail number. All current moths may carry their existing nationally issued sail numbers until such time as the boat is sold, and then the new owner shall revert to using the ISAF ICF Plaque number as their sail number along with their country code.

HHeeiigghhtt nnoott lleessss

tthhaann 225500mmmm

WWiiddtthh nnoott lleessss tthhaann 115500mmmm TThhiicckknneessss nnoott lleessss tthhaann 3355mmmm

SSppaacciinngg -- nnoott lleessss tthhaann 5500mmmm

It may not always be possible to fit the emblem, sail numbers, and country code within the 60% limit. Some of the „storm sails‟ or „mini rigs‟ in use at the moment are shorter in the leach length and, and hence their sail numbers at the required size and spacing would be proportionally lower down the sail. Appendix G only states that the 60% rule should be adhered to „when possible‟ and the case of the „mini rigs‟ would be allowed. If the spacing of numbers and country letters was compromised by the location of battten pockets, and they needed to be located slightly differently to avoid placement over a batten pocket, this would also be considered acceptable.

Arc whose radius is 60% of the leech length. When possible the class insignia, national letters, and sail numbers shall be above this arc.

60 mm minimum spacing from edge of sail

Starboard side letters and numbers are uppermost. Country code above numbers, and both of the same colour.

9.3 Triangulation Method of Sail Area Calculation

Any sail measured after the 31.12.2004 is to be measured using the triangulation method. The intention is to measure the entire sail area when extended to its limits. For the triangulation method the sail has to be divided into a number of suitable triangles. Any arrangement of the triangles on the flattened sail is possible. For a common moth sail the subdivision according to the diagram on the measurement form as shown below is recommended. The area between the battens is divided into two triangles by a diagonal, which always starts at luff segment top and ends at leech segment bottom.

If the sail has less battens than indicated on this diagram, it is easiest to mark a „fake batten‟ to the sail, and use this within the measurements.

When measuring a sail using the addition of triangle areas, the IMCA sail area calculation Excel spreadsheet should be used. The length data of foot, battens, leech & luff sections, and the maximum perpendicular offsets of any rounded regions are entered into the spreadsheet. The total area is calculated and presented at the bottom of the sheet, calculated to 2 decimal places.

The maths behind the spreadsheet is based on the fact that for a triangle with sides of lengths a,b and c the area is;

where s is the semi-perimeter

All of these triangular areas can be added up to give a total area of the divided up sail.

Measurements of the sail are entered into the relevant sections. The calculated area is displayed below this list, rounded to two decimal places.

If there are any rounded regions such as an element of foot, head or leach round. These areas can be calculated as such:

The sail measurement spreadsheet comprises a front sheet where the data is entered, and a calculations sheet. The calculations sheet can be accessed via the tab at the bottom left of the main spreadsheet. These formulas should not be edited.

Luff and foot bolt ropes are not included in the sail area measurements. Sleeve luff sails are allowed a deduction (after calculation of total area) of luff length AB x 50mm. This is undertaken within the spreadsheet, as it assumes the sail being measured is a sleeve luffed sail. If measuring a bolt rope sail the 50mm figure within the calculations section should be amended.

Maximum perpendicular offset

Length

9.4 Measurement Procedure

The measurement of sail area is probably open to the greatest variance unless consistent methods are adopted. Sails to be measured do not necessarily need to be dry, but it is preferable that they are for accuracy.

An assistant will be required to hold the other end of the tape measure. It is preferable that this is not the sail owner. If doing the measurement with two people it is often easiest to write down all of the measurements onto a paper copy of the measurement form, and then enter the data into the computer spreadsheet afterwards. If another spare person is available who can undertake data entry the procedure is much quicker, although the measurement should be undertaken somewhere quiet so the recorder can easily hear the measurements being called out.

Care should be taken with the file naming and saving of the spreadsheet if several sails are being measured. A file name of the sail number is common.

The serial number of the sail should be identified and recorded. Many sails have a little identity tab inside the luff tube near the tack. If a sailmaker's serial number is not evident then the measurer shall allocate one (eg, GBR4050/1) and endorse the sail accordingly with an indelible ink marker.

For sleeve luffed sails with camber inducers in, these should be removed for measurement.

Check the class emblem, sail numbers and country code for compliance with the class rules and RSS Appendix G. Another measurement check that should be made is that with battens tensioned in their pockets, they do not extend more than 150mm from the leech.

The sail should be pinned out on a flat level surface with sufficient tension to remove wrinkles and waves in the sail material. If it is not possible to pin the sail out, care must be taken to ensure the sail is pulled with sufficient tension to remove wrinkles and waves in the sail material when each measurement required within the triangulation method is taken.

Mark the sail at both ends of the intersection centerline of the batten to the sail edge. At the luff use either the inner side of the luff rope or prolong the centerline of the batten to the forward edge of the sail, if it is around the mast. On a black luff pocket it may be necessary to mark onto strips of masking tape in the appropriate positions. If the sail has less battens than indicated on the measurement diagram, an extra „dummy batten‟ should be marked onto the sail so the same number of measurements are utilised.

Measure the lengths of all the luff sections, diagonals, battens, and leach, carefully following the order on the measurement form.

If there is any foot, head or leech round, the maximum perpendicular offset should be measured from the line between the nearest batten end reference points, and recorded. This may require the use of a string line.

All measurements should be in millimeters.

If the sail encloses the mast, a value of 0.05m * the sum of all luff segments has to be subtracted. This is undertaken within the current spreadsheet, but if the sail encloses the boom, a value of 0.09m * the foot length has to be subtracted, and this option is not currently in the spreadsheet, and should be subtracted manually if required.

With the exception of the area reduction allowed by the rules for sails that enclose the mast or boom, small areas where there is no sail material present near the tack, head or clew should not be subtracted from the total sail area. An example of this would be where the luff pocket ends before the tack point.

The sum of all triangles and any extra areas (subtracted by the luff pocket and the boom pocket if applicable) is the sail area, rounded mathematically within the spreadsheet to 2 decimal places. If a sail calculates to 8.004m2, please remember that this does not exceed 8.00m2 when rounded to two decimal places at the final total area. If there is an area of hollow that is not taken into account by this measurement system this should be measured and subtracted from the total area accordingly.

Making a sail 'Measure' If a sail is oversized, once measured, it is the responsibility of the owner to determine how to make it measure within the 8.00m2 line. This is most commonly done by trimming the foot of the sail. The spreadsheet can be used to clarify a foot measurement that would bring the sail within the area rule. This measurement can be marked onto the sail, to allow a fair curve to be drawn through this point and the excess trimmed off.

When the sail area has been calculated as complying and all checks on the emblem, sail numbers and country code are complete then the sail should be signed, dated and the area marked in indelible ink near the tack.

The completed measurement form should be signed, dated, stamped and presented to the owner. This can be either a paper copy of the measurement results, completed and signed at the time, or the electronic version can be printed, signed and sent out at a later date.

10. PROHIBITATIONS

A final section of the rules is a list of prohibited items. “11.1 Moving or detachable seats and trapezes are prohibited.” The seat system as used on the International Canoe is not allowed, as would be any system where wingbar tubes slide within each other to change the position of the helm relative to the hull centreline. “11.2 Catamaran or multihull configurations are prohibited. Sailing any tybe of permitted hull design consistently as a catamaran or multihull is also prohibited.”

This has been discussed already within the hull measurement rules. See section 7.6 for details. 11. ENDORSEMENT OF CERTIFICATES AND MAINTAINING VALID MEASUREMENT

Where sails are measured subsequent to the original measurement, then the measurer concerned shall fill out a new sail area measurement form accordingly. The dimensions are all added to the Measurement Certificate then signed and dated on the understanding that the sail area measurement form is attached by the owner to the existing measurement forms. The Class has no specific requirements for annual checks or buoyancy testing, but the owner should be reminded that it is his responsibility to maintain the boat to the standard required for full compliance with the rules, especially in respect of buoyancy. If there have been significant alterations and changes to hull, spars and sails since the original measurement, an owner is required to have a boat re-measured in full. Should a measurer be aware that this has not been carried out, then he is to inform the IMCA.

12. MEASUREMENT AT CHAMPIONSHIPS

All boats racing at a Championship shall possess a valid Measurement Certificate, therefore measurements at Championships do not have to be carried out 'to the full' but should concentrate on checking essential and vital areas of variance. These may include:

1. Full Sail Area Measurement 2. Overall Length 3. Overall Width 4. Identification Marks

Further checks may be made at random. Measuring procedure details should be included in the programme of the event with times and the location where measuring is to take place. Provision shall be made for 'wet weather' measuring by the erection of tents, marquees or similar.

A separate area should be set aside for sail area calculations and 'event stamping' sails and hulls. It should be emphasised to competitors that it is their responsibility to bring hulls, spars and sails to the relevant area for measurement. The sequence in which measurements will be undertaken should be made evident to competitors eg, Hull: Check in as sailed condition at a 'calliper' station. Mast: Laid out so that overall length and bands can be verified. Sails: Pegging out and measuring areas, sufficient to allow one sail to be measured

whilst another is being laid out or rolled up by the owner. The practice of 'checking sails' by choosing a large sail, measuring it and placing smaller sails over it is condoned, provided all doubtful sails are fully measured. Sails should then be identified, 'event stamped', and a card issued signifying compliance with the specified checks which can then be accepted by the organising club in conjunction with a Measurement Certificate. The exact level of measurement to be undertaken is a matter for discussion by the organising club, and the IMCA. 12.1 Dispute Procedure Unless an International Jury has been convened that has authority in such events over measurement matters, then disputes have to be referred to the IMCA and the boat can sail on a 'provisional compliance' basis. Legal status can be confirmed or withdrawn at any later stage without redress. 13. TRAINING AND EXAMINATION OF NEW MEASURERS

Although dinghy classes with a solid financial base are able to offer full time 'seminar' type training and examination courses, the International Moth Class can only realistically convene its training over regatta weekends and during the National Championship. National Championships are ideal for the observation of experienced measurers in operation, and working alongside them during check procedures invariably provides the first and best introduction possible. The measurer instructing should demonstrate to 'new recruits' the consensus methods of carrying out a full measurement and supervise each prospective measurer through a complete measurement of the boat to ensure that it is carried out competently, with accuracy and understanding. It shall be the responsibility of the I.M.C.A. to encourage continual maintenance and improvement in the standard of measurement techniques by recognised Class measurers.