# Thread: Meter boats?

1. ## Meter boats?

Some one please explain what is meant by meter boats. I read in B&R where this guy has a 5.5 meter boat and it is 31' long. Now on my calculator 5.5 meters is a little over 18'.

2. ## Meter rule

If it was only that easy.
Last edited by S/V Laura Ellen; 05-26-2006 at 08:11 AM. Reason: can't type

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4. ## Measurement Formula

The meter measurement is the result of a formua.

The universal rating rule was introduced at the turn of the century and was given in feet. The rule consisted of measuring all boats against a base boat using the variables of sail area, length and displacement. Prior to the universal rule, several other rating systems were used but none of them took displacement, one of the principal determinants of speed, into consideration. Soon after the universal rule was adopted, the international rule was introduced. This rule generally governed the 6-, 8-, 10-, 12- and 23-meter yachts and it considered girth, freeboard, sail area and length.

5. Knight Errant
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You didn't put enough variables into your calculator.

Metre boats are a development class, not a one design. That is to say, the boats are not all exactly the same, but when the boat is measured, the measurements are entered into a formula, and the answer to that formula is the boat's rating.

For 2.4m, 6m, 8m and 12mRs, that formula is (Length on the Waterline + 2 times the "girth differential" - freeboard + the square root of the sail area)divided by 2.37. The rule is specific on how to measure the length, etc. The object is to allow the designer to trade off different aspects of the boat, but allow them to race on an equal footing.

If you look at the formula, you'll notice that if you want to keep the result the same, but want to add sail area, you'll have to modify one of the other parameters... such as reducing length. This makes it possible to design a boat that is better suited for local conditions. The 12mRs that raced for the cup in Newport tended to be shorter and had more sail area than the 12s that raced off Freemantle. But if the Doctor didn't blow, the shorter boats would still be competitive...

The 5.5mR class is similar, but the rule is different.

if you go to the 8mR home page (www.8mR.org) and click on the class button, then the rules button, you'll have a link to the 8mR rule, which will explain how the different areas are measured.

6. Thanks, now I almost understand.

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Originally Posted by Thad
That was a great article. Thanks!

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## Chad, just keep in mind that the rules.....

two main parameters are sail area and length of water line. The reason that the boats have such low freeboards and long overhangs is that they are meant to be sailed on their sides, thereby taking advantage of unmeasured length.

If you live in a place where it's light all the time you would want a boat with less waterline (wetted surface) and more sail area. If you live in San Francisco you would want a boat with more waterline and less sail area, since you don't want to be overpowered all the time (this is slow).

That's one of the interesting things about meter boats: if you want to race your boat you need to know it's history. Were I to buy my dream 6mR and take it to Puget Sound for racing I may just bomb out unless my particular boat were built to at least be decently fast in their mostly light conditions. No matter how beautiful or well rigged, my boat may never win. Even the most skilled driver may not be able to compensate for the design.

The 5.5 class is interesting in that they sail in three divisions: Modern, Evolution, and Classic. It's the same rule, but the boats are completely different because the philosophy in yacht design has evolved over the years. The 5.5 that I had was a 'classic'. Full keel with attached rudder. Other than that it just looked like a smaller 6mR with a jib. The 'evolution' 5.5's are long overhang boats like the originals, but they usually have a separate keel, skeg, and rudder. The modern boats look nothing like what they used to look like. You want to imagine a modern 5.5? Well, look at any ACC boat and there you have it. The Cup boats look almost identical in profile to the 5.5's being built by Wilke and the other builders.

A new 5.5 will cost you at least \$150K once you get the trailer and covers and things. They normally build about five boats a year for people in Switzerland, the Netherlands, Finland, etc. It's interesting that the five boats they build are basically one-designs that come out of the same mold. Even in the 5.5 class costs have pretty much killed the developemental aspect of the thing to a degree. A new 6mR will run you \$350-500K. I don't really know how much they cost because there have been so few built over the past 10-20 years. The last US 6mR to be built was somewhere around 1983 (an S&S design named 'Tempest'). There is talk that a new boat has been commissioned to a design by Juan K, the big-time ACC designer. The 6 that I recall being built was to a design by the German Julianne Hempel. The big 'thing' with 6's is to find an older boat and restore it. The fleet is Seattle and Vancouver, along with the new fleet in Maine, are almost entirely of the 'classic' variety. For us wooden boat enthusiasts that's a great thing. Most of these boats look better (and are certainly faster) than they were when they were first built.

Well, that's just a short discussion of the metre classes. I could go on for hours if anyone wanted to talk about it. Don Z. can fill us in on the 8's, probably the most beautiful of the metre boats. I also love the look of the square metre classes like the one that Noah is interested in. My Dragon is basically a skerry cruiser design and that is a wonderful look. For beauty of design there is no comparison with any other type of boat. Ah. I love talking about boats. Especially these boats.

Mickey Lake
Last edited by bamamick; 05-26-2006 at 03:03 PM.

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The meter rule was described by someone as if someone gave everyone the same blob of clay, and you could form it they way you want. When you add something here, you have to take it away there. The main factors are waterline length, draft and sail area. The various components add up to a quantity in meters. The universal rule was simlar, but the measurements weren't metric. The formula generally favors long, skinny, deep draft boats with overhangs.

10. Knight Errant
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Originally Posted by Dan McCosh
The meter rule was described by someone as if someone gave everyone the same blob of clay, and you could form it they way you want. When you add something here, you have to take it away there. The main factors are waterline length, draft and sail area. The various components add up to a quantity in meters. The universal rule was simlar, but the measurements weren't metric. The formula generally favors long, skinny, deep draft boats with overhangs.
Draft is not measured by the formula, but limited by the rule. The 8mR rule states: The maximum draught allowed shall be 16 per cent of the LWL plus 500 mm. If the draught exceeds that
allowed, three times the excess shall be added to the rating.

Displacement is also not measured, but it's taken into account by the girth differential.

The Universal Rule was different in that it placed the length and sail area in the numerator, and the displacement in the denominator. Additionally, extremes were limited because the length was measured at the quarter beam, that is to say half the distance between the extreme beam at the water line and the centerline of the boat. In the International Rule, the length is measured at a point somewhat above the load water line. For an 8mR, technically it's "The length “L” for the formula shall be the length measured at a height of 1.5 per cent of the class rating
above the LWL (120mm) plus one and one-half times the difference between the chain girth at the bow
section measured to points 5 per cent of the rating (400 mm) above "L" and twice the vertical height from "L"
to those points, plus one-third of the difference between the chain girth, from sheerline to sheerline, at the
stern ending of this length, and twice the vertical height at the side of the yacht at this station. For the
purpose of calculating the rating the minimum difference of girth at the bow station, as defined above, shall
be 3 per cent of the class rating (240 mm), the minimum difference of girth at the stern station, as defined
above, shall be 10 per cent of the class rating (800mm).
The afterbody of the yacht shall be so shaped that an after chain girth measurement can be taken in a
vertical transverse plane intersecting the after overhang at a height of 3 per cent of the class rating (240 mm)
above the LWL (L2).
If one-third of the girth difference (i.e. the chain girth from sheerline to sheerline less twice the vertical height)
at this station, L2, is less than 65 per cent of one-third of the stern girth difference at L1, the deficiency shall
be added to the stern girth difference in calculating the yacht's rating. The horizontal distance from L1 to L2
shall not be less than 255 mm. The girth measurement at L2 shall be taken to the upper edge of the
topsides at the girth station."... aren't you glad you asked?

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## Just so happens that I received a history of....

the 12 metre class in the mail yesterday. I had ordered it from a second hand shop on line. Looks like hours of interesting reading.

Mickey Lake

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