SailNet Community banner
1 - 11 of 11 Posts

·
An Aussie Sailor
Joined
·
122 Posts
Discussion Starter · #1 ·
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
 

·
Registered
Joined
·
5,117 Posts
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.
 

·
An Aussie Sailor
Joined
·
122 Posts
Discussion Starter · #3 ·
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
 

·
Registered
Joined
·
547 Posts
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
 

·
Registered
Joined
·
652 Posts
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
 

·
Registered
Joined
·
547 Posts
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
 

·
Registered
Joined
·
656 Posts
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
 

·
Registered
Joined
·
652 Posts
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.
 

·
An Aussie Sailor
Joined
·
122 Posts
Discussion Starter · #11 · (Edited)
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

Thanks, It's an interesting link. It does not list my boat (I did not really expect it to) so all I could was pick a design that had some specs like mine (that I knew) and see what came up.

The original owner/builder must have had some degree of confidence in his boat as I have it on record he sailed it out in Bass strait on more then one occasion.
I know it will simply and safely round up if overpowered in a gust.
I've been out in 4-5 metre swell, seemed to handle it fine although not something I'd look to do every day.
Obviously I'm not planning on passage making in this boat but it's still of interest to me to know it's history and to get as much data on the design as I can. I'm comfortable with it's ability as a coastal cruiser.
It's heavier rigged then some comparable sized boats I've seen, dual swept spreaders, solid glass in hull and deck.
The designer was very well known in Australia and as I understand it even had experience in America Cup boats.

Mychael
 
1 - 11 of 11 Posts
Top