NMBR is easily adjusted to produce distance racing handicaps.

The idea behind it is quite simple and yet simply copying the same approach to Texel / ISAF and Yadstick systems will not result in the same accuracy.

Here an explanation of how it works

Pretty much we can devide any race over three main courses.

-1- Pure upwind sailing (as high as one can)
-2- Pure down wind sailing (as low as one can)
-3- And the widened area of reaching (anything between the regions of -1- and -2-)

-1- is most impacted by righting moment and pointing ability.
-3- is most impacted by having a spinaker or a jib
-2- is mostly impacted by good hull design and efficiency of the traditional sailarea (only main and jib)

Right at this moment both the spi hit and the righting moment correction are implemented as follows. (I only give part of the equation, only the working core.

(0.5 * spi hit + 0.5 * righting moment corr) / 1

The 0.5 is actually a course distribution factor. We have currently taken 0.5 as most data I have right now suggest that a non-spi boat takes about roughly 50% of the time to go upwind. Some tweaking can be done here.

By changing this course ratio to say 100 % upwind and 0 % downwind we can produce custom handicap numbers for races like the Tybee 500 and steeple chase. Of course any ratio between 0 % upwind work and 100 % upwind work is possible. By changing these ratio's one can see that the impact of both the spi hit and limited righting moment hit are forced to influence the ratings proportionally to the sailed course.

Smart people will notice how the reaching leg in not implemented yet but by adjusting this formula too :

(Downwind portion * spi hit + (1 - downwind portion - upwind portion) + upwind portion * righting moment corr) / 1

and use 2 percentages to defined the course. Portion upwind and portion downwind. The reaching portion is then the remainder.

This way we can modify the framework by including the reaching legs. On these legs no spi hit or righting moment corrections are taken and so the pure speed potential under traditional sails (main and jib) is taken and assumed to be fully powered up all the way over the conditions.

The framework is simple to implement and by adjusting just two input variables the excel sheet will produce ALL the new custom handicaps for a distance race within a blink of an eye.

It can be proven theoretically that the accuracy of the rating is somewhat less than those for a well layed out bouy race (for which the rating were optimized) HOWEVER, the same proof shows that the NMBR custom rating will be noticeably more accurate than all other systems in use today. Simply because it DOES compensate for the different course shape of the distance race AND because it does so in a way that is SIMILAR to what happens in real life. To how real life physical processes determine the performances under the different distance racing conditions. Ex. We all understand how sailing 90 % of the time upwind and 10 % of the time downwind under spinnaker proportionally impacts on the benefit of having a spi. The shown framework does compensate in exactly the same way.


The same framework can not easily be copied and used with Yardstick systems as in Yardstick systems the distribution between upwind, downwind and reaching performance is simply not known. One needs this in order to have them impact on changing course distributions.

Texel nor ISAF can easily use this setup untill they change the way that they implement the spi hit. By this I mean that they can't use it untill they have decoupled the spinnaker and jib related performance on the downwind legs. This is pretty fundamental stuff and many important people unquestionably want to discuss such a thing at great length.

So distance race organisers !

There is also a better mouse trap for you guys.


Wouter