All rating rules contain acronyms and abbreviations, although IRC less complex than most, with minimal inputs. This page does not replace the IRC definitions which are part of the full Rule text, but is a quick guide.
- IRC: International Rating Certificate
- RORC: Royal Ocean Racing Club, joint owners of the IRC Rule
- UNCL: Union Nationale pour la Course au Large, Pôle Course du YCF. Where this website refers to UNCL please read as YCF (from Dec 2022).
- YCF: Yacht Club de France, joint owners of the IRC Rule
- TCC: Time corrector IRC (the ‘rating’)
- ERS: Equipment Rules of Sailing published by World Sailing, direct link at bottom of Rules page (most IRC measurements are taken in accordance with ERS)
- RRS: Racing Rules of Sailing published by World Sailing, direct link at bottom of Rules page
- WS: World Sailing
- ISAF: (International Sailing Federation) changed its name in November 2015 to World Sailing. Where this website still refers to ISAF please read as World Sailing.
Hull
- LH: Hull Length (note that sales brochure Length Overall sometimes includes pulpit/bow roller, not included in LH)
- LWP: Waterline length
- BO: Bow overhang
- SO: Stern overhang
- y, h, x: Additional measurements taken at the bow and stern
- DLR: Displacement/Length Ratio
Rig
- P: maximum hoist point of mainsail (on mast)
- E: maximum outhaul point of the mainsail (on boom)
- J: from the mast to the forestay attachment point
- FL: Forestay length
- SPL: Spinnaker pole length
- STL: Spinnaker tack length
Mizzen rig
- PY: maximum hoist point of mainsail (on mizzen mast)
- EY: maximum outhaul point of the mainsail (on mizzen boom)
Mainsail
- MUW: Mainsail upper (7/8) width (ie. taken 7/8 of the way up the leech)
- MTW: Mainsail three quarter width (ie. taken 3/4 of the way up the leech)
- MHW: Mainsail half width (ie. taken 1/2 way up the leech)
Headsail
- HLUmax: Maximum luff length on any headsail
- HLU: Luff length of largest headsail
- HLP: Luff perpendicular – from clew to luff
- HHW: Headsail half width (ie. taken 1/2 way up the leech)
- HTW: Headsail three quarter width (ie. taken 3/4 of the way up the leech)
- HUW: Headsail 7/8 width (ie. taken 7/8 of the way up the leech)
- HSA: Headsail area
Flying Headsail
- FLU: Luff length of flying headsail
- FLP: Luff perpendicular – from clew to luff
- FHW: Flying headsail half width (ie. taken 1/2 way up the leech)
- FTW: Flying headsail three quarter width (ie. taken 3/4 of the way up the leech)
- FUW: Flying headsail 7/8 width (ie. taken 7/8 of the way up the leech)
- FSA: Flying headsail area
- FSFL: Flying headsail foot length
- FSHW: Flying headsail half width
- STLFHmax: Maximum tack point for flying headsail
Spinnaker
- SLU: Spinnaker luff length
- SLE: Spinnaker leech length
- SFL: Spinnaker foot length
- SHW: Spinnaker half width (half luff to half leech)
- SPA: Spinnaker area
Mizzen staysail
- LLY: Luff length
- LPY: Luff perpendicular
Stability and safety
- STIX: Stability Index
- AVS: Angle of Vanishing Stability
- SSS: Safety & Stability System
- ISO: International Organization for Standardization
- OSR: Offshore Special Regulations published by World Sailing, direct link at bottom of Rules page