Headsail & spinnaker definition 20th November 2002 PDF Print E-mail
Sunday, 25 January 2009 01:56
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 This e-mail address is being protected from spambots. You need JavaScript enabled to view it or This e-mail address is being protected from spambots. You need JavaScript enabled to view it at the RORC Rating Office, tel 01590 677030.