Author Topic: Rule 302. 90 deg Test  (Read 4959 times)

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Offline SloopJohnB

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Rule 302. 90 deg Test
« on: November 11, 2007, 22:54:45 PM »
Having downloaded various draft/verisons of the rules, it is apparent that there is some confussion with is rule (90 deg test). Such as the weights used.
These range from 130 to 140 kg  for minimum (for 15.50 mast lenght) and 170 to 190 kg for maximum weight.
What are the correct weights?

One of the draft rules had a clause related to Bmax (3.70 m) where the weight is proportional increased to a reducing in Bmax. Has this been taken out?
If so why?

From what I can see this would penalize the narrower beam boats as the inital righting moment would be less for the consponding same weight when at 90 degress.
Am I correct on this?

I look forward to your replies.

PS Have any boats been tested yet?

Offline Charles Bertrand

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Re: Rule 302. 90 deg Test
« Reply #1 on: November 12, 2007, 10:33:32 AM »
Hi,

Indeed, even the online French and English versions of the rule differ...
In the French text, the 90° is solely intended at restricting the ballast weight and trying to ensure the boats have enough 'structural weight' to preserve their integrity. Whereas in the English version, there is an extra statement indexing the righting moment at 90° in the beam of the boat, therefore helping the narrower boats to compensate their righting moment.
I've asked JM Vidal (guy behind the rule) about which version is the final one and to correct the old one.

If the French version is correct, the moment to be applied at the top of the mast at 90° is min: 2015 kg.m and max: 2635 kg.m
If the English version is correct, the moment to be applied at the top of the mast at 90° is min: 2015x 3.70/Bmax kg.m and max: 2635x 3.70/Bmax kg.m

I hope to have an answer soon.
As far as I know, I don't think any boat has yet been tested.
Latest news is that the assembly will be on Saturday 1st of December in the afternoon within the facilities of the Paris Boat Show.

Offline SloopJohnB

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Re: Rule 302. 90 deg Test
« Reply #2 on: November 12, 2007, 20:40:49 PM »
Thanks for your reply Charles

The english version defintely helps the narrower beam boats. I hope it is version correct.

For example a boat of 3.3m Bmax would be able carry 1000 l of water ballast.
Plus the 90 deg test the weights would be 146 kg min, 190 kg max. This would be like having an extra 120-125 kg of extra lead in the bulb.

Why I suggested 3.3m beam, is that I like feel boats over 33-34% Bmax/LOA just look to fat.

All the best will the Paris Show, hope it goes well for your team, and the boat generates much interest in the Class.
Following with interest.

John
« Last Edit: November 12, 2007, 20:47:35 PM by SloopJohnB »

Offline Charles Bertrand

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Re: Rule 302. 90 deg Test
« Reply #3 on: November 13, 2007, 09:49:13 AM »
Hi John,

You're not going to like it but i've been told the French version is the latest one. Therefore the keel ballast weight will not be varied to encourage narrower designs. I'm still waiting for confirmation but will let you know as soon as possible.
Thanks for your encouragements.
Regards,
Charles

Offline Charles Bertrand

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Re: Rule 302. 90 deg Test
« Reply #4 on: November 13, 2007, 16:08:40 PM »
Got confirmation.
The only indexation that should be in the rule are:
1-for the 90° test: weight at mast tip varies according to mast length to keep the same moment
2-for the water-ballast volume: the total volume varies with the beam of the boat as follow: Total volume = 900 x 3.70/ Bmax

That second point is the only measure taken to encourage narrower designs.
The online English version should be corrected soon.
Regards,
Charles

Offline NicoG

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Re: Rule 302. 90 deg Test
« Reply #5 on: November 14, 2007, 01:25:28 AM »
Thanks Charles for the effort and to let us know.

Offline SpeedyG

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Re: Rule 302. 90 deg Test
« Reply #6 on: October 07, 2008, 18:13:53 PM »

These range from 130 to 140 kg  for minimum (for 15.50 mast lenght) and 170 to 190 kg for maximum weight.


Hi,

can anyone explain, why there is a maximum weight limit ?
Is there a technical reason (except breaking the mast while testing )?
The more uprighting moment, the safer the boat, isn't it ?

Do they simply want to avoid people building extremely light hulls and putting
all the remaining weight into the bulb ?

Cheers,

Thomas

Thomas Rauch
SpeedyG, GER 521

Offline Charles Bertrand

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Re: Rule 302. 90 deg Test
« Reply #7 on: October 07, 2008, 19:24:16 PM »
You've got the answer already. Having a max righting moment at 90° should limit the chase for structural weights and hopefully promote safer structures...