IRC RULE

MEASUREMENTS OF SAILING BOATS

For Turkish Offshore Racing Club

And

Turkish Sailing Community

PLAN

– Introduction : IRC PRINCIPLES

– Part 1 : HULL MEASUREMENTS

– Part 2 : RIG AND SAILS MEASUREMENTS

IRC PRINCIPLES

- IRC Self declared measurements

- Assistance of an IRC Appointed Measurer

- IRC Appointed Measurer required for

IRC WEIGHING and ENDORSED CERTIFICATES

OFFICIAL DOCUMENTATION

– IRC Rule + IRC Notices :

• www.uncl.com and UNCL IRC Yearbook• www.tayk.org• www.rorcrating.com and RORC IRC Yearbook

– ISAF Equipment Rules of Sailing :• www.isaf.org

MEASUREMENT EQUIPMENT

The owner or measurer shall use measuring instruments with a degree of precision and accuracy

that matches the measurements being taken.

- Metal tape measurers and rulers (various lengths depending on the measurement),- Spirit levels,- Plumb lines,- Floating wooden tape rulers,- Adhesive tape, cords, note book, pencils, permanent marker, screwdriver…

BASIC PRINCIPLES

NO TOLERANCES ON IRC MEASUREMENTS

- IRC Rule 19.8 deals with RATING REVIEW, the tolerances are applied in the case of a control by a measurer.

- Declaring the measurement, the owner shall declare the “measured” ones; he shall not artificially diminish the measurements using IRC Rule 19.8.

BASIC PRINCIPLES

– A MEASUREMENT SHALL BE ACCEPTED AT A TIME “T”.

Measurements may slightly vary for environmental or meteorological reasons (moisture, temperature…).

DATE AND SIGN ALL YOUR MEASUREMENTS

– IRC uses the MKSA[1] Metric system (See IRC Rule 12)

• Sails measurements: in metres to two decimal places.• Other linear measurements: in metres to three decimal places.• Weights expressed in Kg• Boats’ weights rounded to the nearest 10 kilograms.

[1] MKSA : Metre, Kilogram, Second, Ampere

EXISITING MEASUREMENTS

– Other measured rating systems (IOR, IMS ORC Club and PHRF).

Part of those measurements can be used provided that the boat to be measured matches the certificate of measurement presented in order to make sure that the owner has not made any changes.

– As a general rule, overall hull length, max beam, draft, are reliable form one certificate to another. Changes made to any of those parameters are visible.

Other measurements, such as weight, overhangs and sails measurements should be carefully treated if coming from another certificate.

IN CASE OF DOUBT

– Always refer to Official Documentation

– Refer to other IRC Measurers

– Refer to the UNCL IRC Rating Office VIA TAYK.

PART ONE

HULL MEASUREMENTS

MEASUREMENTS ON LAND

– For accurate measurements, the boat in a horizontal plan. For that, use a spirit level. The operation may be difficult.

– Those measurements (Bmax, Draft, LOA) are not necessary for production boats with no modifications.(in such a case, inform the IRC Rating Office about the series’ name and the draft).

– Those measurements are required only for “One off” and the first of a mass production boat.

– Those measurements may be required for “Endorsed” certificates.

LOA, HULL LENGTH– LOA: The length overall of the hull excluding bowsprit and

other rigging if any, stem fittings, stern fittings, pulpits, any overhanging rudder and rudder hangings.

– When the boat ashore on a horizontal plan, place a plumb line at the forward, another at the aft. Measure between each plumb lines and an intermediate fixed reference point.

LOA = A+B

A B

BMax, MAXIMUM BEAM

– Beam: the maximum horizontal dimension of the boat in any transverse section, excluding any rubbing strake or toe rail.

– Inspect for maximum beam station sighting from off the boat. Do it from both ahead and stern of the boat. It is easy to be fooled by the shape of the boat. Maximum beam is nearly always further aft than you think. If in doubt, check several stations to find a maximum value.

– Using a level held vertically at the point of maximum beam, measure inboard to a convenient point on the deck of the boat. Repeat from the other side.

DRAFT

Draft : The maximum depth of the boat or any of its appendages below the water plane, in the condition of Empty Weight (see Rule 22.0).

In the case of any movable appendage, which is not fixed down while racing, the minimum depth is also required (keel fully up and fully down).

Draft is measured in 2 steps : ashore and afloat.

DRAFT- Ashore

Establish a convenient reference point on each side of the boat above the waterline in way of the section at maximum keel depth.

Using a spirit level, project horizontally from the underside of the keel outboard to vertically below the reference point each side. Measure vertically down from each reference point.

Measurements ashore on each boat side:

-A: Starboard-B: Port

DRAFT- Afloat

Everybody shall be off the boat when measuring and the boat shall be empty (IRC 22).

Measure vertically downwards form the reference point each side to the water surface.

By subtraction from the ashore figures, and then averaging the result, draft is found.

Water line

Measurement afloat on each boat side:

-A’: Starboard-B’: Port

DRAFT = [(A-A’) + (B-B’)] / 2

MEASUREMENTS AT SEA

Each measurement afloat is done with the boat in EMPTY TRIM (IRC Rule 22).

NO WINDAND

FLAT WATER PLANE REQUIERED

OVERHANGS: BO, SO, y, x, h

IRC Rule definitions:

– BO The horizontal distance from the forward point of LWP to the forward limit of LOA, in the condition of Empty Weight (see Rule 22.0).

– SO The horizontal distance from the aft point of LWP to the aft limit of LOA, in the condition of Empty Weight (see Rule 22.0).

Using a pair of plumb lines attached to the extreme ends of the hull (excluding fittings) at bow and stern; use a floating wooden rule to measure the overhangs at bow (BO) and stern (SO).

– y The vertical distance from the water plane to the lowest point on the transom, in the condition of Empty Weight (see Rule 22.0).

Using the plumb line at stern, measure along the line the distance from the end of hull to the water plane. Only one EXCEPTION : reversed transoms:

Scow Bow or knuckle exposed• x The horizontal distance from the forward

point of LWP to the lowest point on the stem at a tangent of 450 to the horizontal, in the condition of Empty Weight (see Rule 22.0).

• h The vertical distance from the water plane to the lowest point on the stem at a tangent of 45° to the horizontal, in the condition of Empty Weight (see Rule 22.0).

Scow Bow or knuckle exposed

Using a Spirit Level 45° inclined, mark the relevant point on the knuckle.

Best method is to mark the point when the boat is ashore, and to measure when afloat.

Profile view

Rear view

Upper view

150 m

170 mm

+/- 10mm

45°

400 mm

+/- 10 mm

Continuous graduation in centimetres

Hole for plumb line

HO

LE

M 2M 1

Read « h » on the vertical scale

BO

x

X = BO – M1*0.707 – M2

Water line

IRC WEIGHT - WEIGHT CERTIFICATE

– Weighting device shall be done by an appointed IRC measurer.

– IRC Measurer shall be able to proof to the owner and to the Rating Office that the load cell he uses is well calibrated (it shall be calibrated at least once a year).

– NEVER USE DATAS PROVIDED BY A TRAVEL LIFT, NEITHER CRANE’S LOADCELLS.

– When a boat weighed, overhangs measurements shall be provided to IRC Rating Office.

– Several items shall be removed, others shall stay aboard. Rule 22 explains how to prepare a boat properly before weighing.

– Never weight with more than 10 knots of wind.

– A weight certificate shall be provided to the owner. Each parts shall be filled and the document shall be signed both by the owner (or his representative) and the official measurer. If not, this document will not be accepted as valid by the IRC Rating Office.

Weight certificate Checklist– Part A “Tanks”: note gasoline and water into the boat’s tanks.– Part B “Internal Ballast”: note any internal ballast weight, their position, and the type of fixation.– Part C “Accommodations: for each item, note “Aboard” or “Removed” with the number of

removed items, or “No Object” if the serie’s boat is not fitted with an equipment (for instance, no table in a Melges 24: “No object”). Note the number and type of batteries.

– Part D “Movable chest” or Cockpit boxes: ( J 109, First 36.7, First 40.7, IMX 40, IMX 45)– Part E “Other accommodations”: take note of specifics and anything that appears to be unusual.– IRC Rating Office shall be informed if the yachts are weighed with or without those various

equipments, as the IRC weighted boat shall race in the same configuration.– Part F “Mast and rig”: note the most details you can : mast and rig material, Checsktays, runners– Deduction :

Tare: remove from the gross weight all the fittings necessary to weight (straps…)Gasoline: remove from the gross weight the quantity of gasoline aboard when

weighting multiplied by 0.9.Water: remove from the gross weight the quantity of water aboard when weighting.Others: all items not removed before weighting in spite of they should be.

– Note the measured overhangs, date and place. Measurer and owner shall sign the document.

Any incomplete IRC Weight Certificate will be refused by IRC Rating Office.

PART TWO

RIG AND SAILS MEASURMENTS

P The hoist of the mainsail measured on the mast, from the top of the boom when set at right angles to the mast or the corresponding top of a permanent 25 mm band of contrasting colour, and the bottom of a similar 25 mm band at the top of the mast above which the mainsail shall not be hoisted.

If there is no top band the measurement shall be taken to the top bearing surface of the halyard shackle.

P is never measured directly from the sail

E The foot of the mainsail measured along the top of the boom set on the centre line and at right angles to the mast, from the back of the mast to the inside of a permanent 25 mm band of contrasting colour beyond which the mainsail clew point shall not be set.

If there is no band the measurement shall be taken to the aft end of the boom.

E is never measured directly from the sail.

J The base of the fore triangle measured as the horizontal distance from the front of the mast at deck level to the point where the forestay meets the deck, projected if necessary.

The point where the forestay meets the deck may depend on your rig type.

FL The forestay length measured from where the forestay meets the deck, or from the jib outhaul in the case of a bowsprit, to the forestay attachment point on the front of the mast or to where the forestay intersects the front of the mast, projected if necessary.

STL or (SPL) The length of the longest spinnaker pole, whisker pole or bowsprit measured on or near the centre line of the boat

from the forward face of the mast tube to the extremity of the spinnaker pole, whisker pole or bowsprit,

or the horizontal length from the forward face of the mast tube at deck level to the spinnaker tack point on deck projected vertically as necessary, whichever is the greatest.

SAILS

BASIC PRINCIPLES

For each sail measurement

sails shall be on the floor

and have just sufficient tension applied to remove wrinkles across the line of

the measurement being taken.

Mainsail: MHW, MTW, MUW

– MHW: The half width of the mainsail, measured as the shortest distance between the half leech point and the luff, bridging any hollows in the leech of the sail.

– MTW: The three quarter width of the mainsail, measured as the shortest distance between the three quarter leech point and the luff, bridging any hollows in the leech of the sail.

– MUW : The seven eighth width of the mainsail, measured as the shortest distance between the seven eighth leech point and the luff, bridging any hollows in the leech of the sail.

ONLY MHW, MTW and MUW are measured directly on the mainsail

First, look for the MUW measurement point on the leech, folding the sail (head point on clew point). Mark it on the leech.

Second, look for the MTW measurement point, folding the sail (head point on the MHW measurement point).

Third, look for the MUW measurement point, folding the sail (hear point on the MTW measurement point).

MUW

MTW

MHW

On the biggest genoa, the one with the biggest Headsail Area (HSA), you have to measure LL, LP and HHW (use the same method as for MHW).

LLmax : biggest Luff Length of all the headsails aboard.

Measurements shall be taken using the relevant Clew, Tack or Leech points.

HHW

LP

LL

HEADSAIL TOP WIDTH

HHB The widest headsail top width of any headsail carried measured as the distance between the head point and the aft head point.

Leech Luff

HEADSAIL

HHB

LL

HEADSAIL HEAD BOARD WIDTH

Leech Luff

LuffLuff

Leech Leech

Spinnaker: SLU, SLE, SF, SHW– SF The foot length of

the largest area spinnaker carried, measured between the clew points

– SHW The half width of the largest area spinnaker carried, measured between the half leech points.

– SLE The leech length of the largest area spinnaker carried, measured from the clew point to the head point.

– SLU The luff length of the largest area spinnaker carried measured from the tack point to the head point.

– Same method for symetrical and asymetrical spinnakers. Only the largest spinnaker is declared.

RIG FEATURES

– Mast material, rod rigging or not, number of pairs of spreaders and sweptback angle, jumpers, runners, checkstays, shall be noted on the petition. All unusual features shall be declared to IRC Rating Office (See IRC Rule26.2.2), textile rigging, radar on mast…

– Consistently, applications for IRC certificates are received with erroneous information relating to backstays, runners and checkstays. IRC Rule added the following definition in 2007:

Backstay: An item of running rigging from the masthead to the stern of the boat which may be adjusted while racing.

Runner: An item of running rigging from the mast below the masthead in the vicinity of the forestay to the stern of the

boat which may be adjusted while racing.

Checkstay: An item of running rigging from the mast significantly below the forestay to the stern of the boat which may be adjusted while racing.