I.O.R "ton" ratings, 1/4 ton, 1/2 ton, 3/4 ton...

[sharpii2]

Here's a question that has stuck in my mind for some time.

Just what did the IOR "ton" ratings really measure?

I know that they were used so boats of the same "ton" rating could be raced as equals.

It occurred to me that this rating measured the weight of the likely crew.

A 1/4 ton rated boat would have maybe three crew on board. And if the standard assumed average weight of a crew member back then was taken as 150 lbs, then three of them would weigh 450 lbs, not including their carry on gear. This is very close to 1/4 ton.

Am I out in the weeds on this.

Or am I on to something.

 

[wet feet]

Way off.I'm afraid.It had a bit more to do with the existence of an older trophy One Ton Cup - Wikipedia https://en.wikipedia.org/wiki/One_Ton_Cup .None of which relates to the rather abstruse Thames tonnage that was the earlier reference for British designs.In their era the various categories of level raters probably had the best designers and sailors of keelboats engaged in very close racing.

 

[jehardiman]

Yeah, it was all about a hitting a particular measurement, first as a class rule, then RORC, IOR, and IMS. So for a modern( 1965) One Ton first under RORC you had to hit 22 feet, then after 1971 under IOR it was 27.5 raised to 30.55 in 1983. After 1994 it went to IMS and VPP and then back to a rotating one design. Similailary, all the other tonners had to hit their own ratings, that is why IOR IIIa was such a cluster...so many boats changed rating overnight.

From the ORC site;

Level rating classes – the Ton Cups

The IOR Level Rating Classes (Ton Classes) were popular at the leading edge of IOR racing until keen racing owners gradually began to turn to IMS designs in the early nineties. Ton Classes had originated with Jean Peytel's idea to revive the old 6-Meter trophy, the One Ton Cup, for competition without time allowance between yachts rating 22 feet under the RORC Rule. The One Ton Class was followed in 1966 with the Half Ton Cup and the Quarter Ton Cup in 1967, both on the initiative of the Societe de Regates Rochelaises, and Pierre Chambonnet in particular.

In 1967 the Yacht Club Italiano started the Two Ton Cup and in 1974 the North American Yacht Racing Union presented the Jean Peytel trophy for the Three Quarter Ton Cup at 24.5 feet IOR rating. In 1973 the clubs that started the original Ton Cups generously presented the trophies and the right to administer the races to the ORC. In 1984 the Two Ton Class was discontinued and the maximum rating of the One Ton Class was raised to 30.55 feet. The One Ton Class became very popular at this new maximum rating and in 1990, following competitor demand, the Two Ton Class was re-introduced with a maximum rating of 35.05 feet.

 

[sharpii2]

Rats!

And I thought I had a good narrative going.

I figured that all of these boats used human ballast, so bigger boats would need more of it than smaller ones. And bigger boats would need bigger crews anyway.

Having never raced (at least not officially), I presume that the definition of human ballast is any crew member who is not busy doing something else, while on watch.

The math in my head created the seeds of my narrative. I figured a 1/4 ton boat would need a crew of three, and might end up with a crew as small as two, or as large as four.

A 1/2 ton would need a crew of four to six. So, you add them up and throw in a bit of fuzzy math, and you end up with a crew weight of roughly 1/2 ton. And so on.

Well.

It was fun while it lasted.