2010 Changes to Crew weight Rule

Frank's suggestion for changing the crew weight rule

At the World Council meeting in Whitstable, the Japan Tasar Association stated that they feel strongly that the crew weight rule should be changed, and asked for comments and suggestions.  Tasar designer Frank Bethwaite has written suggesting that we should require only three quarters of the difference between 130 kg and the crew weight to be carried as ballast.  With this change, rule C.6.2 would read: In the event that the weight of the crew, thus weighed, shall be less than 130 kg, such crew may race the TASAR, provided that, throughout the event, ballast equal in weight to at least the three quarters of the difference between the crew weight and 130 kg is carried secured in the cockpit.  The ballast carried need not exceed 12 kg.

Frank's letter suggesting this, and a second letter explaining his reasons, follow:

First letter: July 1, 2002 Re: invitation to comment on Crew Weight proposals. In this case I regard myself as sinner-in-chief. I wrote the original Tasar (then Nova) rule in 1972. By about 1985 I regretted that I had not thought harder in 1972 about future "legitimate" lighter crews such as the Japanese.  In 1994/5 came the observations and experience which lead up to "The Third Factor", and the much gentler and more accurate 49er Performance Equalisation rule. From this I learned that the whole subject is much more complex than it appears on the surface.

In 2001 I had a second opportunity, with the 59er, to do a better job than I did in 1972. For the 59er I have written "Everybody is welcome to race with us, but if you do not weigh 330lbs (150kg) you will carry three quarters of the difference as ballast." In my opinion the Tasar class would always have been better served if I had written this in 1972. This (i.e. carrying 3/4 of the difference as ballast) is what I would now recommend. Sincerely, Frank Bethwaite

Second letter: July 14, 2002 Re: Logic for suggesting reduced crew weight ballast Over the years I have learned much, but it has never occurred to me to write down the logic behind what I now  believe. My present theoretical starting points are: -

1. There is a design wind (DW) for every crew for every point of sailing where the apparent wind is forward of the beam.

2. Whatever the crew weight the DW close hauled will be less than the DW on a reach.

3. On all points of sailing with a DW, heavier crews will sail faster than lighter crews in all winds at and stronger than the DW. The first part of the logic is that all sailboats necessarily sail in one of seven modes. There are three points of sailing:

4. Close hauled, - DW applies.

5. Crosswind - between close hauled and apparent wind on beam, ie. DW applies.

6. Downwind - Apparent wind aft of beam so DW does not apply. And there are three wind strengths:

7. Calm to breakout (minimum planing speed)

8. Breakout to DW 9. DW and stronger So the seven modes are: A. Close hauled in Light (Displacement) B. Close hauled in Mod (Planing) C. Close hauled in Strong (Planing, overpowered) D. Reach in Light (Displacement) E. Reach in Mod (Planing) F. Reach in Strong (Planing, overpowered) G. Run

10. Drag tests on hulls always show that hulls develop less drag when lightly loaded than when more heavily loaded.

11. If other factors are equal (eg wind, sail area etc) this drag difference suggests that more lightly loaded boats should beat more heavily loaded boats.

Long observation confirms that in many lightly built classes with modest sail area and no performance equalisation rule, very light crews absolutely dominate the race results. In these classes, heavier crews can never win. The reason is that heavier crews must necessarily sail slower in 5 of the 7 modes ie. A, B, D, E, and G. They will sail faster in 2 of the 7 ie. C and F. So the statistical bias against the heavier crew is 3 of 7 (5 slower but 2 faster) and this statistical disadvantage of 3 in 7 is overwhelming. Against this theory, what have we done?

In the case of the Nova, now Tasar "Full compensation" rule, I now realise that I unwittingly loaded the dice even more heavily the other way. A lighter crew who carries full compensation ballast: -  Has lost all advantage, so has no plusses at all. -  Is disadvantaged in modes C and F -  AND is also disadvantaged in the upper parts of modes B and E, because with the lesser righting moment he/she will reach the DW sooner and sail slower thereafter in B and E as well. So the statistical bias against the fully compensated crew is 4 of 7 (4 slower and none faster). This is worse than the bias the other way if no ballast is carried. No perfect solution exists. As between flat water and waves, and boats with fixed beam and those with sliding wings, and ocean races with no turns and gravel pit racing with myriad turns, everything counts and everything changes as the race environment changes. But the irreducible facts are those above. I make no apology for writing the "Full compensation" rule in 1972 now thirty years ago. At that time we were faced with a crisis in that the philosophical raison d'etre of the NS14 class was being threatened by a new situation in which adult helms and lighter, generally male adolescent forward hands were winning and displacing adult helms and adult, always heavier and generally female forward hands. I did what I could to stem the hemorrhage.

I am proud that I did it. I am proud that it worked and that as a result the Tasar class is a haven for magnificent women. None of this changes the fact that in the light of what we know now the rule is far too draconian, and is grossly unfair to lighter crews such as the Japanese. Back to the technicalities: No system can hope to equalise performance over a wide range of crew weight. The best that can be done is to select, or design for, a target mean weight, and establish a system which will approximately equalise the finishing scores, over a series of races to a particular specification, of crews within a range of say plus or minus ten per cent of that target weight. If we accept that that is the best we can do, it is now self-evident that a system of no compensation is too heavily biased toward lighter crews, and that a system of full compensation is too heavily biased toward heavier crews. The ideal has to be some intermediate system which balances the pluses and the minuses more equitably.

I have no crystal ball.

In 2002 I have written "150kg and three quarter compensation" as my best estimate of what I think will best serve the 59er class in the years ahead. I suggest to the Tasar class that they will be better served world-wide if they opt for "130kg and three quarter compensation", than if they stay with the full compensation rule.


Frank Bethwaite