Monday, 25 May 2009

3 Lengths; Overall, Boat or Hull?

I received a mail from Greg who writes about the the wording in the definition of Zone and how sailors interpret those:



I enjoy using your blog to help clarify my own understanding of RRS.

Here is a local issue in my area that might be worth a post & response. This is not an issue from the elite levels, but I think a concern in recreational racing fleets. This is another area where careful wording in the rules needs to become careful wording in discussions, so sailors are not inadvertently lead astray.

Whether it was the previous rule, or the current definition of Zone, we continue to informally refer to the distance as boat lengths rather than hull lengths (as defined in RRS). This has caused some interesting confusion among local competitors in boats such as International 14s, which in the past used the informal wording of "boat" to define their distance from the mark. The sailors included both the hull and the extended bowsprit multiplied by 2 to determine the "circle" heading into a mark where the bowsprit was deployed.

When they were reminded in discussions of rule changes that RRS 2009 defines Zone as 3 "Hull" lengths, they responded that the 2009 revision would effectively decrease the size of the Zone compared to their past practice.

International 14


Is this an issue in other localities? Shouldn't we quit talking about boat lengths and say or write hull lengths when we talk about the Zone. From my perspective, using the term "hull length" consistently would help clarify the situation for competitors.



Hi Greg, thanks for you input!

You are absolutely right in referring to the zone in Hull-lengths always!

I know there are several rules which have to do with measurement or the position of boats, their equipment and the place it is normally used in (at starting, finishing or to determine the zone). But for the zone, the circle should be fixed for all boats in the same class.

The international 14, who has a retractable bowsprit, would otherwise have a different zone depending on how far the bowsprit is extended. The rule makers wanted to avoid any misunderstanding in that regard and (I suspect) deliberately chose to use hull length. You can find those in the class rules drawings and it should be fixed within a small tolerance. That tolerance should – at most –produce a difference in the zone of a couple of centimeters, not enough to make any difference on the water.

In some older rule books the zone was defined by two boat lengths or two overall boat lengths. Without a variable “length” – like with the bow sprit of the more modern 14 – that was also a fixed measurement. Carbon materials were not available generally and even the most seasoned hickory would have split in those dimensions. (Hickory is a wood used for hammers and axes – because of it’s tensile strength) To my knowledge, they did not have retractable bowsprits in those days… I’m talking about 80’s…

If in the previous rule cycle, sailors used to measure the zone with an extended bowsprit, they did not use the correct definition and that can lead to misunderstanding.

If the sailors in International 14 class feel that three hull-lengths is not enough to prepare for rounding a mark, they have the possibility to increase the zone to four hull lengths, provided it is clearly stated in the SI. Talk to the club and / or RO. I bet they are willing to provide amended SI’s to that effect. With four hull lengths the zone should come to a little bigger then two with an extended bowsprit – if I judge the dimensions correctly from the photo’s

Greg is also asking for responses from other local sailors. Please leave a comment if you have something to contribute.



  1. The definition of 'lengths' for purposes of room at marks was changed from 'overall lengths' built in to old rule 42.2 to 'hull lengths' in the definition of zone in the major 1995-96 rewrite of the rules.

    I've also heard this silly rumor that it has changed in the 2009 rules. I have no idea where it came from, but it has been _hull_ lengths for nearly 15 years.

  2. Changing the Zone to 4 hull lengths in the SIs is fine and legitimate for sprit boats, if they are sailing one design - and provided no other class happens to be rounding the same mark simultaneously.

  3. Hi Greg;
    The International 14 World Championship was held at Wakayama, near Osaka, Japan in 2003. I served as a Jury secretary and an Umpire of the Team Racing. The International 14 World consisted of fleet races and team races according to the class standard SIs format. The team races were four countries’ match, GBR, USA, AUS and JPN. As the wind was very strong throughout the regatta, I have a clear memory that our jury boats could not chase I14 boats very often and there were many dangerous scenes when rounding marks because of boat’s high speed. Based on Appendix D, Team Racing Rules, the definition Zone distance is changed to two hull lengths.
    My moderate opinion;
    As a minimum, change the Zone into 3 hull lengths for Team racing.
    When appropriate, change the Zone into 4 hull lengths for Fleet racing.
    sen yamaoka May 27, 2009

  4. How is the boat circle defined in mixed fleet racing. For example, if you hav 25 ft vs 40 ft boat, what determines/defines the three boat circle?

  5. The definition states that the boat who's nearest to the mark is to be used for determining the circle.

  6. So if 40ft boat is 120ft away and a 20ft boat is 80ft away...the 40ft boat doesn't have rights unless it overlaps the 20ft before 60ft correct? In reverse, it's interesting that samller boat can gain rights over a larger one well before its own 3-boat length. Makes sense. However, with multiple boats appoarching and rounding, when does the nearest boat designation get "handed off"?

  7. @Anonymous
    Have a look at:
    Perhaps reading that, you can answer your question?


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