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Code Zero's and PHRF

13 Jul 2010

From the recent B&G Simrad 50 SSANZ received two protests in regards to sails used not matching declared measurements for their PHRF certificate. It would also appear that there could be quite a few other boats in the fleet that would be in breach.

SSANZ encourages all competitors to check their declared measurements online at This will enable you to search for a boat.  If it has PHRF the name will be in blue  - click the name and get the PHRF details.

Although some errors in dimensions will be an oversight or due to complacency there is also the possibility of misunderstanding in regards to "Code Zero" type sails.


Code Zero's and PHRF


PHRF is a performance based system, which adjusts according to your race history. 

When racing under PHRF please ensure that you read the
PHRF Rules, and understand the main concepts:

You must declare any changes that affect the performance of your boat: This includes for example changing to a longer prod, adding weight to the keel, or adding bigger sails, as well as changes that don't exceed measurements but which do affect performance, such as a square topped mainsail. But it doesn't include replacing like with like.

PHRF is self regulating. If you believe a competitor is not racing within his/her measurements, you should protest them on the racecourse. PHRF certificates are available online for competitors to view at 


So what are the relevant rules ?

PHRF Measurement Rules (

Rule 2 of the PHRF measurement rules (quoted below) is the key in regards to code zero's

2. The method of measuring sails shall be set out in the IMS/ORC-Club regulations in force at the time, unless otherwise stated. It is not intended that sails shall be officially measured unless they have been declared to be of a size which exceeds the normal dimensions which may be carried without penalty under the IMS /ORC-Club J measurement and spinnaker widths.

Current IMS regulations

The relevant rule for Code Zero's being G6 (quoted below) 

G6 Spinnakers

G6.1 The half width of any spinnaker shall be 75% or more of the foot length, except that for a Code 0 type of asymmetric spinnaker half width shall be equal to or more than 55% and less than 75% of the foot length.


So what does this all mean ?

Essentially a Code Zero is currently measured as either a headsail or gennaker/spinnaker dependant on it's half width.

Half width is found folding the head to the tack marking the halfway point on the luff and then head to the clew and marking halfway point on the leech and measuring between these two halfway points. (i.e green line in the diagram below)

If this Half width is greater than 55% of the foot (yellow line in diagram) AND the sail contains no battens then the sail can be measured in as a Gennaker/Spinnaker otherwise it gets measured in as a headsail.


The red and pink lines in the above diagram represent the leech of the sail. In the case of the red line the Halfwidth is less than 55% so the sail would be declared as a headsail whereas the pink line the Halfwidth is greater than 55% so the sail would be declared as a gennaker/spinnaker

It does NOT matter if the sail is attached to the forestay or otherwise.

The Grey Area

There is some conflict between the measurement diagrams at the bottom of the PHRF rules and the current IMS rule in regards to halfwidth % in regards to determining between headsails and spinnakers. It would take a Protest hearing to get a interpretation of the rules. The safe option is to declare anything under 75% halfwidth as a headsail. But you would have a very good case in measuring a Code Zero with between 55% and 75% halfwidth as a spinnaker/gennaker. If in doubt declare all measurements and describe the sail when submitting your PHRF application.


Other Points to consider

1.) If declaring and using a Code Zero that measures as a headsail you will also need to declare any change this may have on J and I measurements

2.) In some cases a yachts biggest spinnaker/gennaker or jib/genoa isn?t the biggest sail in all dimensions. i.e No.1 kite is tall and narrow but the No.2 kite is shorter but slightly wider. In these situations SSANZ advises competitors to declare to YNZ all dimensions of the sails that are bigger in one dimension than the largest declared sail. 


PLEASE NOTE This article is believed to be correct at time of publishing but SSANZ takes no responsibility for the accuracy of any of the above information and encourages competitors to read the rules and make their own interpetation. PHRF regulations may well change in the future.