Specifications for old IOR Quarter ton class. - SailNet Community
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post #1 of Old 05-30-2009 Thread Starter
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Talking Specifications for old IOR Quarter ton class.

I'm either not looking in the right places or that data is just not around but I've been trying for some time to get (in general terms) the specifications/design data to which boats would have to complied with to have met the Quarter ton Class in IOR.

The reason I ask is that I have negligible data my boat (designed to meet quarter ton) and I've been unable to find much at all.

It's a lead fin keel, spade rudder, masthead rig of 26ft length.

I'm reasoning that as it was built to a class specification then that specification should at least give me some common data about my boat.

Stuff like Offshore category rating, AVS (Angle of Vanishing Stability), keel weight,ballast ratio and designed total weight. General stuff like that.

Somewhere that data must exist, not specific to my boat but at least to the class.

I have contacted the designer, he's past 80 and unable to help. The original owner/builder has passed away, the factory that made the hulls is long defunct.
I contacted Yachting Australia and was told they don't have data for the old classes. I've posted on other yachting forums and to quartertonclass.org , all with no results.

I am amazed at how difficult it is to trace a boats history unless it was something remarkable but even more surprised I cannot find standard design specs either.

So looking for help people.

Mychael
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post #2 of Old 05-30-2009
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The various IOR "ton" classes were just boats that rated the same under the IOR Rule. It's really just a prediction of speed potential. Many different designs built by different manufacturers could be rated as "quarter ton" or "half ton" or "one ton". Not sure what the numbers were for each rating.
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Quote:
Originally Posted by JimsCAL View Post
The various IOR "ton" classes were just boats that rated the same under the IOR Rule. It's really just a prediction of speed potential. Many different designs built by different manufacturers could be rated as "quarter ton" or "half ton" or "one ton". Not sure what the numbers were for each rating.

Yeah it's the "numbers" I am looking for. I was thinking there would have been some standard criteria to which all boats in the class must have been built to.

MychaEL
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Go to Boat Design Net - the Boat Design and Boat Building Site and do a search for "IOR rule". Lost of useful threads that may give you your answer. Looks like a quarter tonner rated 18.5 or less.
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Mipcar,

I think JimsCal is right, most of the quarter ton rule boats would have different charateristics.

I use to race on an MB24 built in Perth & I know they were originally built to the quarter ton rule. The Observer's Book of Sailing Craft of Australia and New Zealand confirms this, which states:

The MB24 is Dutch designers Van de Stadt's thinking of the Quarter ton rule.

Stats on this boat are
LOA 23ft 6"
Beam 9ft 2"
draft 4ft 5"
Displacem 1,950kg
sail area 356sq ft

Flicking thru the book other quarter ton boats mentioned include:

Admiral 26 - designed to rate 18 ft for quarter ton competition
LOA 23ft 4"
beam 8ft 4 "
draft 4ft 7"
displacement 2,041kg

Cavalier 26, described as "...now outdated by the latest dinghy type quarters.
LOA 25ft 6"
beam 8ft 9"
draft 4ft 8"
displacem 2,134kg

Spacesailer 22 "...recently been rated for Quarter ton racing
LOA 22ft 4"
beam 7ft 10"
draft 4ft
displacement 1,202kg

Also I believe that AVS is a fairly recent calculation, from around the 1990's. I doubt if you will find any AVS info on 1980's IOR designs.

Hope this helps.

Ilenart
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post #6 of Old 05-30-2009
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Stuff like Offshore category rating, AVS (Angle of Vanishing Stability), keel weight,ballast ratio and designed total weight. General stuff like that.
Mychael[/quote]

The Angle of Vanishing Stability is a calculation that can be done on any boat. US Sailing has an AVS calculator.

Angle of Vanishing Stability

s/v Paloma, Bristol 29.9, #141
Slipped in Bahia Marina, easy access to Corpus Christi Bay and the Gulf of Mexico.
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Johnshasteen,

that website gives an estimate of the AVS, note the qualifiers in the website. Also I have found that trying to get an accurate measurement of the hull (not including the keel) in feet can be difficult and can further distort the calculation.

Ilenart
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post #8 of Old 05-30-2009 Thread Starter
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Quote:
Originally Posted by JimsCAL View Post
Go to Boat Design Net - the Boat Design and Boat Building Site and do a search for "IOR rule". Lost of useful threads that may give you your answer. Looks like a quarter tonner rated 18.5 or less.
.


I am in that other forum group. Posted a similar question there and got no answers.

Mike
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Send a message via Yahoo to dacap06
Sail Boat Calculator

I don't know anything about the old IOR classes, but if you know the name and model of your boat, perhaps the Sail Calculator page will tell you the specs you want. Be sure to look the entire page over as there are several approaches embedded in it.

DaCAP

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S/V Tranquility Base
1984 Islander 30 Bahama
Pasadena, MD
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post #10 of Old 05-30-2009
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Quote=Ilenart;490820]Johnshasteen,that website gives an estimate of the AVS, note the qualifiers in the website. Also I have found that trying to get an accurate measurement of the hull (not including the keel) in feet can be difficult and can further distort the calculation. Ilenart[/quote]

Ilenart, next time your boat is out of the water, take the measurements - I did and you can come pretty darn close. However, well before I did that, I had been through a Force 10 storm with Paloma and knew from experience that she would round up windward from flat down in the water, sails filled with water. On the other hand, if the boat in question is a plastic, fin keel, spade rudder round the bouy racer or lake/bay cruiser, then the owner doesn't need to know the AVS because they have no business venturing into blue water where one might encounter heavy weather.

s/v Paloma, Bristol 29.9, #141
Slipped in Bahia Marina, easy access to Corpus Christi Bay and the Gulf of Mexico.
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