It has come to our attention that there may be some confusion over the definition of a headsail/spinnaker, where the half width is around 75% of the foot/LP.

The relevant IRC rule is 26.3.4:

26.3.4 RRS 50.4 shall not apply.

A headsail is defined as a sail tacked down forward of the foremost mast with half width (measured as a headsail) not exceeding 75% of LP. Any other sail set forward of the foremost mast is a spinnaker and shall have half width (measured as a spinnaker) greater than 75% of foot.

The rule applies in the order it is written. Therefore:

  • If the sail satisfies the definition of a headsail (ie. HHW not exceeding 75% of LP)
    then it rates as a HEADSAIL.

  • If the sail does NOT satisfy the definition of a headsail then it rates as a SPINNAKER, and then the SHW must be at least 75% of SF.

As an example, for the following sail:

Measured as a headsail:
LL 15.90
LP 8.47
HHW 6.00 (71% of LP)

Measured as a spinnaker:
SLU 15.90
SLE 14.90
SF 8.91
SHW 6.70 (75.1% of SF)

When measured as a headsail, HHW is less than 75% of LP. This sail therefore rates as a HEADSAIL. It is then irrelevant whether it complies with the spinnaker definition or not.

If you have any queries on this, please get in touch with Mike Urwin or Jenny Howells at the RORC Rating Office, tel 01590 677030.

This interpretation is given in accordance with Rule 6.7 and is valid for the year 2002 only


1. When a boat is measured with bunk cushions, bunkboards or other permitted detachable items aboard, do these have to be in their normal positions for racing, or merely carried on board?


1. The condition for weighing and for the measurement of LWP and draft is given by Rule 22 which inter alia states:

22.1.2 Main engine installed, or outboard engine aboard in stowed position.

22.1.3 Batteries and fitted berth cushions on board in their normal positions if carried while racing. These items will be noted on the boat’s certificate.

22.1.4 All permanent fixtures and fittings and items of accommodation whether detachable or not, including washboards, bunk and floorboards and saloon table (if fitted for racing) on board in their normal positions.

For the purposes of measurement therefore, there is no doubt that detachable items shall be in their normal positions. For this purpose, ‘normal position’ is defined as the position in which the item would be when in use for its proper purpose. Any item not in it’s normal position would become an item of ‘Loose gear’ and would therefore be removed from the boat for weighing and measurement.

Rule 27.1 states:

27.1 The rated parameters assume that the boat is fitted out at least to the production specification and/or to the condition when last measured/inspected. If another rating certificate is being used as the basis for data then any changes since the issue of that certificate shall be notified to the rating authority.

It is implicit within the first sentence of this rule that the boat is raced in the condition in which she was measured.

Detachable items permitted by Rule 22 to be aboard for measurement shall be carried in their normal positions while racing.



Mike Urwin

Technical Manager 29 April 2002

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