IRC definitions 2001

Measurement Note: ISAF Equipment Rules of Sailing (ERS) Part II, Definitions, Section G, Sail Definitions, shall apply to sail measurement except as stated by IRC Rules or this Appendix. Sails shall be measured in accordance with ERS Part III, Measurement Rules, Section H5, Sail Measurement.

Age Date The year in which the boat was first launched, or the year in which the boat was re-launched following hull modification, whichever is the later.

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

Batten Any material added to the sail, as either a removable element, permanent stiffening, or other contrivance, the purpose of which is to support and/or stiffen the sail.

Beam The maximum horizontal dimension of the boat in any transverse section, excluding any rubbing strake or toerail.

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).

Checkstay An item of running rigging from the mast significantly below the forestay to the stern of the boat which may be adjusted, either directly or indirectly, while racing.

Draft The maximum depth of the boat or any of its appendages below the waterplane, 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.

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.

Empty Weight The weight of the boat to the nearest 10 kg, in the condition of Empty Weight, less the weight of any deductions to the nearest I kg (see Rule 22.3).

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.

h The vertical distance from the waterplane 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).

Heavy Weather A headsail which complies with Special Regulations Paragraph 4.26: A heavy-

Jib weather jib of area not greater than 13.5% height of the foretriangle* squared and without reef points. *vertical height from sheerline abreast the mast to forestay attachment point on mast.

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

HHW The Headsail Half Width of the largest area headsail measured as the shortest distance between the half leech point and the luff, bridging any hollows in the leech of the sail.

HTW The Headsail Three-Quarter Width of the largest area headsail measured as the shortest distance between the three-quarter leech point and the luff, bridging any hollows in the leech of the sail.

Internal Ballast Lead or other material, not in the keel and bulb, which has no practical function in the boat other than to increase weight or to adjust fore and aft trim.

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.

LL The luff length of the largest area headsail when stretched sufficiently to remove any creases.

LLmax The longest luff length of any headsail when stretched sufficiently to remove any creases.

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.

LP The luff perpendicular of the largest area headsail measured as the shortest distance from the clew point to the outside of the luff or luff tape. For a cutter rig with more than one forestay, LP is measured as the shortest distance from the aftmost clew point of any jib or headsail when set on the centre line of the boat, to the foremost forestay.

LPY The longest luff perpendicular of any mizzen staysail, measured as for LP.

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.

Movable Ballast Lead or other material including water which has no practical function in the boat other than to increase weight and/or to influence stability and/or trim and which may be moved transversely but not varied in weight while a boat is racing.

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 mainsail tack whichever is the lowest, and the bottom of a 25 mm band of contrasting colour at the top of the mast above which the mainsail shall not be hoisted. If there is no band the measurement shall be taken to the top bearing surface of the halyard shackle. In the case of a gaff rig, the upper measurement point is the head of the mainsail at the peak or the head of the topsail if carried.

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.

Series Date The year in which the first boat of the class or production series was launched.

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.

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).

STL (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.

Storm Jib A headsail which complies with Special Regulations Paragraph 4.26: A storm jib of area not greater than 5% height of the foretriangle* squared, and luff maximum length 65% height of the foretriangle. *vertical height from sheerline abreast the mast to forestay attachment point on mast.

Variable Ballast Water carried for the sole purpose of influencing stability and/or trim and which may be varied in weight and/or moved while a boat is racing..

Wingspan The maximum horizontal width in any transverse section of any wing, wings or bulb attached to any appendage.

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).

y The vertical distance above the waterplane of the aftmost point of the hull on the centreline (in the case of a counter stern projected to the aft end of LOA) in the condition of Empty Weight (see Rule 22.0).