1/4 ton 1/2 ton etc please explain

I've asked the question of seriously knowledgable people and have never got an answer that explains what 'ton' has to do with it.

There is a definition for each under the IOR rule. Multiple (or add?) up a load of parameters and if it is under a certain value it is a quarter-tonner, half-tonner etc.
 
In the early days there were a number of rough and ready schemes for measuring the size of boats for commercial and racing needs. Perhaps the most popular was Thames Measurement and this persisted almost to the present day, some old timers will still refer to a wooden boat as a 2 1/2 (very small) or 8 Tonner. Thames Measurement was a rum system which used length, bredth, cargo space and the skippers inside leg measurement to arrive at the given number - as you say no relation to displacement.
If we accept that the various rating rules grew out of earlier practice then it is perhaps understandable that the notion of tonnage persisted. Many will still find it easy to picture an older style 1/2 or 1/4 tonner.
 
AFAIR from racing in the IOR days, the rules were aimed at calculating a 'nominal length' or some such term, from the actual measurements of each boat.

The Ton, Half, Quarter, etc 'classes' were each given a 'length' and the designers had almost free reign to work the hull shapes and measurements to achieve the best speed for that nominal length.

The Ton Rules produced boats which were cranky and tender, and without real downwind speed. Measurement points produced funny almost square hull shapes with longish overhangs.

They were pretty difficult to sail optimally, and lost value very quickly as any new wrinkle (e.g. 'bustles') to take advantage of the rule made older boats very quickly uncompetitive.
 
I believe that it comes from the time when the IOR rating system was coming up with a level rating. The royal thames club had had a one ton cup prize for a class of thames racing yacht which was no longer being raced for and hence this was chosen as the cup to race for, the first level rating IOR boats were around 38'

Then owners of smaller yachts wanted to have a level rating class and hence the 3/4, 1/2 and 1/4 ton classes evolved being roughly 34', 30', 24' and then the mini tonners at 18'

But this could have been bar talk, the important thing is that the racing was close and the boats were fun to sail. What happend to Smokey bear, Panda, Nausicca, Heart of Gold (named after the hitch hikers guide space ship) Juno, Local Hero...that was back in 1985 in Porto Ercole
 
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Tonnage in old boats refers to the Thames Measurement of a yacht. Nothing whatsoever to do with the weight of the boat but an arcane system of calculating the size of a boat allowing for its beam as well as length (but not I think its draft). The term derives from the medieval method of defining the size of a vessel by how many tuns (barrels) of ale it could carry.

Different again is the Registered Tonnage and Gross Tonnage. A suprising number of owners think the tonnage carved on their main beam is the weight of their yacht but they are wrong.

Tim w
 
IOR Rule: Internationa Offshore Rule
Intention: a measurement system that gave an assessment of the speed of a yacht and alowed a handicap number to be calculated
IOR handicaps were expressed in feet
Level rating bands were set to group boats of a similar size together and create level rating competions.
The rating bands were set at:
IOR rating of 16.5 = minitonner (&minimum size of boat quaifying for an IOR rating)
IOR Rating of 18.5 = quarter tonner
IOR rating of 21.5 = haf tonner
IOR rating of 24.5(?) = 3/4 tonner
IOR rating of 27.5 = 1 tonner, modified in 1982 to be 30.5 for 1 tonner to synchronise with the minimum rating for the admirals cup
IOR rating of 50 = maxi class (maximum rating issued)
simples.....
 
unikely unless measured under the IOR rule the rating number aso comes out at 18.5. Overall length is just one measurement that goes into the rating calculation. IOR "feet" are not measurements of length.

Two almost identical boats could have different ratings depending on the size of spinnakers/mainsail (or a host of other things) and so rate e.g. 21.3 and 21.5 feet ....... but be exactly the same length.

If you think IOR was confusing, then don't even start exploring IMS (which followed)
 
My E-Boat is an IOR Mini-Ton class racing yacht. Its just under 1 Ton displacement, and 22 foot long. Figure that then!! Thats how the ruling goes. Its wierd, thats a fact!
 
Handicap Rules all come down to one of two things:
1. a correction of your actual time so that boats of different sizes and shapes can race against each other
2. using a set of measurements with a final rating (number) all boats race against each other and the first across the line wins

If you do any racing, you will quickly go from confusion (what do the handicaps really mean) to frustration (why do I always seem to lose even when I think I am saiing well) to exasperation (they aways win 'cos the've got a great handicap) eventually to understanding.
Plymouth Yardstick is mainly aimed at dinghies but from the PY number, a TCF (time correction factor) is generated that is then used to adjust your elapsed time and should mean that equally well sailed different boat designs/types can fairly race against each other.

Most yacht clubs run a similar local system or make local adjustments to the national/international systems. Handicap committee members are often well rewarded at the bar or get dogs abuse for their misunderstanding of the performance potential of someone's pride and joy.

google CYCA for the Scottish handicap system
The RORC office administer the IRC system and their website is worth a look

Going back to the original thread topic, the rating rule that was used for the "ton" classes had an annual revision (November Offshore Racing Council meeting) and eventually it was abandoned because the boats were viewed as becoming too extreme, too expensive, not as much fun as they could be for the size/money, not creating good cruiser/racer compromises and a better, newer whizz bang rule was proposed that would cure all the evils of IOR by measuring the hull shape, weighing boats and using a velocity prediction programme so that internationally handicaps any boat could be measured and fairly handicapped. The IMS rule .....

IMS made race boats even more expensive, extreme and complicated and so it was binned.

The ton-cup revivals have come about from those that want to race these "obselete" boats again as despite all the shortfalls, IOR racing in the late 70's and 80's was great fun.
check out the 1/4 and 1/2 ton websites but don't for one minute confuse "feet" with length and "ton" with weight!
 
ProDave said:
My boat's not on that list. The magazine review said 127, so perhaps it was a missprint and they meant 1270 ???
Click to expand...

Maybe it is 1270. The higher the number, the slower the boat.
What is it you have?
Google "your boat Portsmouth yardstick"

That list wasnt the definative list, just one from a particular club.

I also see yer a local lad too!!:)
 
Even Chance said:
Maybe it is 1270. The higher the number, the slower the boat.
What is it you have?
Google "your boat Portsmouth yardstick"

That list wasnt the definative list, just one from a particular club.

I also see yer a local lad too!!:)
Click to expand...

My boat's a Frolic 18. Google that and you won't find much. She was built in 1983 on the South Coast, and I have two magazine reviews from that time both praising the little boat, but (after buying her!!) I found they are as rare as hens teeth, so I can only conclude that for some reasoson not many were made.

We've only just got the boat and she's not in the water yet, but we are hoping to sail her out of either Portmahomack or Balintore, both on the Tain peninsula. We are hoping to get her in the water for a week or two to get some end of season sailing then back out for the winter.
 
This rule produced boats that were so bad that Olin Stephens actually apologised publicly for his part in it's development.That said I used to own a Douglas Peterson designed 1/2tonner that sailed like a wich to windward and was very god on a reach but obviously preformed not so well on a run.An she wasn't in the least tender.
 
The Thames Measurement formula was (Waterline length-Beam) X Beam X Beam X2, all divided by 94.
Long ago the convention was to leave the result expressed as 94ths rather than simplifying to 1/4, 1/2 etc. So my 21 foot cutter built in 1882 with a WL length of 18 feet and a beam of 6 feet 6 inches has a TM of 2 55/94. It does in fact weigh about 2 1/2 tons.

As recently as 1964 my father registered a 30 foot motor cruiser, and was given detailed instructions for having the calculated TM carved on the main beam, together with the "certified chart space". The full meaningless inscription, complete with the 94ths, then had to be traced on paper and sent to Lloyds to confirm that it had been done.

If anybody still owns the motor yacht Lucy Carmichael, ex lifeboat from the P&O liner "Maloja", then the inscription will still be there.
 
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