how about including meniscus in watrline msurement

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how about including meniscus in watrline msurement

Postby s vernon » Sun Aug 30, 2009 11:02 am

I think tanking and measuring the waterline length on an EC-12 is iffy at best, as the measurer needs to guess where the waterline is discounting the meniscus. And weighing the boats would be a pretty much positive but unfair way to measure the boats.

I have had someone tank my boat and tell me 42.5 inches and then I added 9 ounces just to see what effect that would have and they tanked it again and told me 42.5 inches.

How about changing the rule to include the meniscus? Someone could tank a few boats and figure out about how much length the meniscus adds and then the rule could be changed to read something like 42.5 to 43.5 inches including the meniscus.

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Postby Chrispy » Mon Aug 31, 2009 6:46 am

Scott, I have just tank tested my rebult boat (Now finished!!! - new deck/radio etc) and confronted the same problem. The cause of the meniscus is 'surface tension' which is much aleviated by using 2 to 3 drops of dishwaasher liquid in the water. Regards, Chris
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Re: how about including meniscus in watrline msurement

Postby aesch » Sun Aug 29, 2021 5:55 pm

My $0.02 on this issue is that using waterline to control displacement isn't making it. How do you check the winners at a regatta? Setting up a tank and measuring the waterline is a fussy and time consuming job.
I've been at regattas, arriving at the weather mark at the same time as the 'fast boats', only to have them pull away from me on the downwind leg - by 5 to 10 boat lengths! My suspicion (could be wrong) is that these boats are a bit light and are racing with waterlines that are less than minimum.
I'd love to hear thoughts from other racers on this issue.
edit: I would like to see a minimum weight for the boats, like the IOM class. Easy to check.
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Re: how about including meniscus in watrline msurement

Postby bigfoot55 » Mon Aug 30, 2021 8:38 am

Question Al: Does your club have access to a tank, and have all members boats been measured? If all boats in a regatta have a Measurement Certificate, I would hope our skippers were honest in measurement certification.

LWL is a fundamental of 12 Meter design, and the rule dates to the founding of the class. I think we need to live with it. To my mind, the meniscus is not that hard to allow for. Yes, it is a two man job. And for Championship regattas, there should be a tank available in case of a protest. Along with maybe a little DAWN.
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Re: how about including meniscus in watrline msurement

Postby aesch » Mon Aug 30, 2021 11:12 pm

Hi Tom,
Thanks for your reply. I'm a class measurer and have a tank. I've modified the tank several times trying to facilitate measurement of waterline. It's a fussy and time consuming job to level the tank and then adjust the water level in the tank to suit the displacement of the particular hull being measured.
I'm hull #2065, so new to the class. I'm not privy to class history and why things are the way they are. The other two classes I sail (CR-914 and IOM) both have minimum weights. Weight is easy to check and keeps the skippers honest. I have yet to be at an EC-12 regatta that had a measurement tank.
So, please excuse my ignorance and explain to me why waterline measurement is better for the class than weight measurement? Make me a believer.
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Re: how about including meniscus in watrline msurement

Postby bigfoot55 » Tue Aug 31, 2021 9:17 am

EC 12 History shows a number of manufacturers and boats with a waterline length of 42 1/2 plus or minus 1/2 and only a beam limitation of 11.5 inches, location not specified, and more that one actual hull shape. That was limited in 1978 to boats "conforming" to the TREASURE TOOLING mold and measurements. Still more manufacturers were allowed and some modifications made(keel width primarily) , followed by the "95 STANDARD" hull and then finally the 2004? Class molds. This made the boat closer to a one design mold, but there is still a lot of leeway for boat beams in building.
At a NCR about 2004, a spread sheet was made of all boats at the NCR listing various details and weights. I cannot locate that now.
What it showed was there was a wide spread in boat weights.
When Tom Germer was following up on Rick Wests proposal to use a weight standard about 2012 he was trying to figure out how to arrive at an all inclusive weight range that would accomodate all class boats. A herculean task.

NOW it might be possible to arrive at a weight range for boats out of the 'class molds', (wider keels) AND grandfather all older boats to the waterline measurement. It would take a motion to change the class rules approved by the class in AMYA election. Based on history, (I go back to 1973) I would still advocate against it, and am not sure it would eliminate your concern.

We have had Class measurement certificates to make it easier to administer Championship Regattas. Eliminating the need to measure at an event. If a skipper wishes to protest a boat thought to be violating the measurement rules, he should do so. http://www.ec12.org/Admin/Files/EC12_Measurement_Policy.pdf
(We have had a tank available at NCRs held at St Augustine.) We had one at Peachtree City, Oak Hollow, cannot recall the others.
AS a Measurer, have you found anyone attempting to cheat?
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