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Measuring Tank

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Offline ratrod

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Measuring Tank
« on: July 10, 2011, 09:16:21 PM »
We now have a measuring tank sitting at Wattle Farm, maybe we make use of this for the Auckland champs

Offline grant

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Re: Measuring Tank
« Reply #1 on: July 11, 2011, 07:30:23 AM »
We will fill the tank at the Auckland Champs and anyone wishing to test there boats can do so but we will NOT be using it as an official measuring tool until the Nationals in March

Offline Browny

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Re: Measuring Tank
« Reply #2 on: July 11, 2011, 03:15:36 PM »
The last time i looked it still required finishing, has this now been done??

Offline neptune

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Re: Measuring Tank
« Reply #3 on: July 11, 2011, 04:26:32 PM »
I for one am unsure of measuring devices or in particular Tanks who declares them legal ?Is there a standard they are built too ?

If the Tank is not to be used at the Auckland Champs what method will be used  at this event  ? :)
« Last Edit: July 11, 2011, 04:31:25 PM by neptune »
unless otherwise stated views are my own.
bob Atkinson rtd

Offline k4s

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Re: Measuring Tank
« Reply #4 on: July 11, 2011, 05:27:49 PM »
I would imagine anyone turning up with equipment needing to be measured would be frowned on a bit.
Weighing of boats and keels as has been the norm for events will not require a tank.Would be interesting to float the boat for personal satisfaction however.
Free time actually costs more
Richard Batchelor
IOM  NZL743   NZL802

Offline grant

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Re: Measuring Tank
« Reply #5 on: July 11, 2011, 09:26:50 PM »
Well done Richard, I thought it would be obvious that we could not use this until it has been certified legal and as the majority of registered boats in the last 5 years had not been tank tested when first measured.We will how ever  have it certified by the Auckland Champs and skippers can check there boats to see if they are in fact legal.If not they would be expected to have there boats legal by the Nationals where all boats will be tank tested as part of the checking procedure.If they fail I will have chainsaws,gas axe and sledge hammer available for a small charge to make any minor adjustments. ;D ;D ;D ;D ;D ;D

Offline grant

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Re: Measuring Tank
« Reply #6 on: July 11, 2011, 09:30:08 PM »
I must also thank one of our club members Nigel Walls for constructing the tank.It is all glass and looks very impressive.Well done Nigel.

Offline neptune

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Re: Measuring Tank
« Reply #7 on: July 11, 2011, 11:18:22 PM »
(Well done Richard, I thought it would be obvious that we could not use this until it has been certified legal)wich asks the question what is the process of making it(the Tank) legal ?It may be an  obvious  question to some of us others like myself could do with a simple answer.
unless otherwise stated views are my own.
bob Atkinson rtd

Offline hiljoball

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Re: Measuring Tank
« Reply #8 on: July 12, 2011, 03:49:28 AM »
Interesting question.

The ISAF Measurement Guide is available at

http://www.sailing.org/tools/documents/IMManualFeb2009-%5B6939%5D.pdf

Section 8 covers measurement equipment.

Reading it, I get the impression that as our boats are so small, we are within measurement error limits and don't have to worry about accuracy (repeatability) of (say) a good quality tape measure.

When a measurer shows up with a tape measure, we don't ask "Is that tape measure certified'?

A float tank is a device with some limit marks scribed on it made by using a tape measure. So if a few skippers check the placement of the marks and agree that they are accurate, then you have a good tank.

It is important that the tank be leveled and that the water depth be maintained accurately during the procedure. The scribe marks should be on both sides of the tank so that you can line them up with the boat to avoid parallax errors.

One problem with reading in a tank is what to do about the meniscus at the water line as that can be a couple of mm in water (Try to use the flat surface and not the top of the meniscus).

(as an aside, section 5 of the guide suggests that mass (boat weight) varies around the globe due to gravity variation. The closer to the equator, the less the boat weighs . . .and provides correction factors based on latitude. . . now that one is not in our class rules ;D ;D ;D ;D)


John




John Ball
CRYA # 895
IOM V8 CAN 307

Offline grant

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Re: Measuring Tank
« Reply #9 on: July 12, 2011, 10:00:51 AM »
Thankyou once again John for your valued input.How are things in Canada and what design seems to be the most popular.Have you ordered a Britpop yet? I hear the orders are into the sixties.

Offline hiljoball

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Re: Measuring Tank
« Reply #10 on: July 12, 2011, 10:47:55 AM »
Hi Grant,

Our local measurer, Lawrie Neish is also on the IOM Technical committee and he has been working hard on a dry measurement jig. It is much easier to transport and set up and use than a float tank, but is not yet IOM class legal. He sent one to the 2011 Worlds in West Kirby and most. if not all boats were tested on the dry jig before hitting the float tank. I have not yet heard back on the results.

Link to dry measure (and click on the link to watch the video of the jig in use)

http://www.wcmya.ca/hot_topics_jig.htm

http://www.wcmya.ca/wcmya_video/iom_dry_vs_wet.wmv

In western Canada, we have an active IOM fleet with some 'purchased' boats and many scratch built models. Recently I built and then sold an EMO (Frank Russell) and there have been several Brad Gibson Reggaes built just launched, and one SKA completed and two more under construction, including one that I am building. We brought the line plans from Brad and made a female mould to pull of the hulls. We also have several very good sailors designing and building their own hulls. So plenty of action.

John

« Last Edit: July 12, 2011, 11:28:13 AM by hiljoball »
John Ball
CRYA # 895
IOM V8 CAN 307

Offline neptune

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Re: Measuring Tank
« Reply #11 on: July 12, 2011, 03:47:22 PM »
John,
             Read all pages of the International Measures Manual found no mention of a tank except in very very general terms(like tools needed)
But did find comments on using metal tapes and what standard to use,and at what temperature.
unless otherwise stated views are my own.
bob Atkinson rtd

Offline hiljoball

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Re: Measuring Tank
« Reply #12 on: July 12, 2011, 04:06:55 PM »
Hi Neptune,

I think it unlikely that full sized boats would use a measuring tank. . . that only exists for our models. I was drawing attention to section 8 that describes measurement equipment to see if it contained any direction about certification of equipment and found instead that it refers to accuracy of equipment.

This was to relate to the earlier question as to the need/process to certify a measuring tank.

John
« Last Edit: July 12, 2011, 04:10:47 PM by hiljoball »
John Ball
CRYA # 895
IOM V8 CAN 307

Offline neptune

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Re: Measuring Tank
« Reply #13 on: July 12, 2011, 04:15:23 PM »
Yes John i agree...............hard to see large boats in a test tank,i will try and explain away my lack of knowledge...........Not had a lot to do with Iom,s sailed mostly R/M,s and a local boat the Nautic12.
The rules for the class only state
;DIMENSIONS
With the boat floating in fresh water:
minimum maximum
Draught ..............................................................................370 mm .... 420 mm
The depth of hull from waterline .................................................... ....... 60 mm
Hull length ...................................................................................... ... 1000 mm

The Tank has a lot in comman with the Unicorn.
unless otherwise stated views are my own.
bob Atkinson rtd

Offline ratrod

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Re: Measuring Tank
« Reply #14 on: July 12, 2011, 08:42:50 PM »
and guess what the tank is 1000mm long and 420mm to the top funny that!