How heavy is a Hillyard 4 tonner?

A Harrison Bulter Z-4 Tonner displaces 3.5 tons. Can't find the figure for a Hillyard.

The four tons is the racing rating calculated under the final iteration of the Thames Measurement rule (TM). Even after it faded as a racing rule, it remained the way cruising yachts were described in the UK until way into the seventies.

TM = ((L-B) x B x B/2)/94
 
I have a nifty little table of Thames Tonnages. If we ignore the byzantine rules of measurement...

A four tonner might have a Length of:

27ft * 6ft beam
or
24ft * 6.5ft beam
or
22ft *7ft beam
or
20ft * 8ft beam

etc.
 
doug748 said:
I have a nifty little table of Thames Tonnages. If we ignore the byzantine rules of measurement...

A four tonner might have a Length of:

27ft * 6ft beam
or
24ft * 6.5ft beam
or
22ft *7ft beam
or
20ft * 8ft beam

etc.
Click to expand...

I always understood that Thames Measurement was the number of "Tuns"-big barrels-that would fit in the space of the hull. I think it was an old Barge Captain who told me that in the early seventies at Brentford. Please correct me if I am wrong. I think I understand it has little reference to the weight or displacement of the vessel. I await the learned responses of forum members.
 
That's how Tonnage calculations started. It was an easily calculated figure that could be used to compute harbour dues, light dues, pilotage fees and even the cost to the Sovereign of leasing Merchant ships in time of war.

It roughly indicated an equivalent to the number of Tuns (or barrels of 252 gallons) of wine a ship could carry. By 1587 it had been standardised as (L x B x D)/100.

But by the late 19th century the commercial version and the yachting version had parted company. From 1880 Tonnage Rules were the basis of the early attempts at rating rules for racing yachts. It went through many variations and the 'rule cheating' started immediately. The final version lived on however as a measurement of cruising yachts.

The tables above were simply an aide memoir of the main possible variations a given TM could give at the early design stages.
 
Yea I've never understood this either. I used to crew on an 1/4 toner years ago, but it was about 32' and even though it had nothing in it except pipe cots, must have weighed much more than 1/4 of a ton! More like 3 to 4 tons. So it must be cargo weight and not boat weight? Bit a 1/4 tonner must surely be able to carry more than 1/4 ton of cargo?

So the OP's answer could be a complete variable depending what it has in it?
 
35mm said:
Yea I've never understood this either. I used to crew on an 1/4 toner years ago, but it was about 32' and even though it had nothing in it except pipe cots, must have weighed much more than 1/4 of a ton! More like 3 to 4 tons. So it must be cargo weight and not boat weight? Bit a 1/4 tonner must surely be able to carry more than 1/4 ton of cargo?

So the OP's answer could be a complete variable depending what it has in it?
Click to expand...


The IOR explained, it has nothing at all to do with the OPs question
i have an IOR One Tonner

Rule components

The IOR concentrated on hull shape with length, beam, freeboard and girth measurements, foretriangle, mast and boom measurements, and stability with an inclination test. Additionally, the IOR identified features which were dangerous, or it couldn't fairly rate, and penalized or prohibited them. The measurements and penalties were used to compute the handicap number, called an IOR rating, in feet. The higher the rating, the faster the boat was deemed to be able to sail. A typical IOR 40 footer (a one tonner) rated 30.55 feet.

The IOR rule encouraged wide short boats with limited stability. A narrow waterline and large beam on deck, combined with a high centre of gravity, meant that crew weight provided a significant proportion of stability at small heel angles, and boats had a relatively low angle off vanishing stability. This developed into the situation about 1977 when the boats winning in most smaller IOR categories (up to the half tonners - about 10m LOA) had all internal ballast, often with an unballasted daggerboard. The managers of the rule realised that this was not a suitable direction for seaworthy yachts, and heavily penalised boats with lifting keels.

Apart from the girth measurements, all measurements were basically point measurements. This meant that the hull was often locally distorted to maximise or minimise a measurement locally, with minimal effect to the surrounding hull. This gave a characteristic bumped look to many boats, particularly at the point of maximum beam and in the stern. Also, as stability was only measured at very low heel angles (less than 5 degrees), boats were designed with a very narrow waterline and low stability in measurement trim, but a hull form that gained stability with the weight of the crew and other equipment, and with increasing angles of heel. Interestingly, low stability was encouraged (up to a point) because the initial assumption was that low stability indicated a well fitted out interior, and so more of a cruising boat than a stripped out racer.

Secondary design factors included engine and propeller rating factors, minimum internal accommodation levels, safety regulations, and a limit on the number of sails carried on board. Later on, crew limits were introduced, and limits on the use of exotic materials, and also scantlings for hull structural design developed by the American Bureau of Shipping.
Practical implications for sailors and owners

In a handicap race, the IOR length was used to compute a time allowance. In Europe this was calculated on the duration of the race, in seconds per hour, known as Time on Time, whereas in the USA they preferred to base it on the length of the race, as seconds per mile, known as Time on Distance. Time on Distance is easier to calculate at any point in the race, but can cause significant anomalies in tidal waters as the distance sailed through the water can differ significantly from the distance over the ground, due to the effect of the tide.

The IOR rule was also used to define level rating classes, where each class had a maximum IOR rating, and the first boat to finish was the winner, with no handicapping. The first of these was the One Ton class, so named because there was a spare trophy from the defunct One Ton rating class, and this then spawned the Mini Ton, 1/4 Ton, 1/2 Ton, 3/4 Ton and Two Ton classes, as well as unofficial 50-footer, ULDB 70, and Maxi classes. The official classes each had an annual world championships.

The IOR was run by the ITC, or International Technical Committee, of the Offshore Racing Congress, chaired between 1979 and 1987 by the late Gary Mull of San Francisco.[2] As with all published handicapping formulae, there was an ongoing game between the designers finding ways of designing boats that took advantage of shortcomings in the measurement system and handicapping formulae, and the rule makers closing the loopholes to ensure fair racing and a reasonable competitive life for the boats. As the racing became more competitive, the rate of change in the rule accelerated, and also the boats at the top of the fleet became stripped out racing machines that performed well but were expensive and also difficult to sail, and this resulted in a loss of popularity. However even if club sailors could not compete against the top boats, the IOR did generate a reasonably level playing field across the sailing spectrum, with club sailors buying production race boats or custom boats past their prime, and moving up to more competitive boats as they wanted to sail up the fleet. Towards the end of its life the IOR had become a stable rule, but by then it had a reputation of changing too often, and this sowed the seeds for its successors. IMS was introduced as a more scientific rule for racing yachts, driven by the USA, whereas Channel Handicap was introduced by the RORC as a simple club level rule that would hopefully feed people into IOR racing - though in fact it proved to be the final nail in the coffin for the IOR rule.
 
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