New IRC rules on headsails

There is a new IRC rule coming into effect from 1 June which looks at the number of headsails carried on board. Prior to this rule change, IRC did not rate the number of headsails onboard a yacht. IRC previously only rated the largest sail area and largest headsail luff length.

Multiple headsails can give a distinct advantage in two cases:

  • Flexibility in sail wardrobe for varying conditions.
  • The ability to increase headsail area by multiple headsails set flying, particularly for larger boats and in a reaching configuration.

From 2024/5, all revalidation and new applications will require the number of headsails will be supplied with the application and these sails must carry suitable measurement stickers or stamps. The number of headsails the yacht is rated for will be printed on their certificate. A heavy weather jib will not be included in the count if it is in accordance with ORS 4.26.2(a). Storm jibs are also exempt where in accordance with OSR 4.26.2(b). The furling headsail allowance and heavy weather jib effects will be incorporated into the calculation framework to simplify the rating authority requirements associated with these sails. 

This IRC rule does not limit the number of headsails that maybe carried by a yacht. It does, however, apply a rating effect where this count goes above or below a base number. A boat with a greater number of headsails than the base will see a TCC increase, and when less than the base will see a TCC reduction. This base number is dependent of the LOA of the boat ranging from a minimum of 2 up to 5 sails (LOA 5m to 20m). A base headsail number will be calculated from the boat’s parameters and the boat will not see their TCC change when using this base count. 

The following table shows the estimated range of TCC when the headsail count is varied from 1 headsail to the number shown.

DesignQuarter TonnerSun Fast 3300First 40Ker 46Grand Soleil 46.3TP52Maxi 72
Number of sails4556677
TCC range0.0030.0050.0040.0070.0090.0090.008

The new IRC rule is:

21.4     All sails, certified after 2023 and used onboard a boat with an ENDORSED IRC Certificate, shall have a measurement sticker or stamp which includes the required IRC dimensions and sail area if applicable. The stamp shall be placed at the head of the sail, except for sails where the head may not easily be inspected (e.g. furling sails) in which case, the stamp may be placed at the clew. The measurement shall be carried out by a sail measurer approved for IRC measurement by their Rule Authority, MNA or an In-House Official measurer and shall date and sign the stamp with the identification mark issued to that measurer. This rule may be amended by a Notice of Race or a Rule Authority.

Organising Authorities can amend that rule when running Category 1,2 or 3 races, and allow yachts to carry an additional headsail (IRC Rule 11.2).

For more information about IRC click here.
RORC’s FAQ (which is excellent) can be read here.

By Chris Zonca 

Australian Sailing