Meter formula

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The meter formula is a measurement formula for classic regatta yachts of the meter class . Yachts with the same racing value (English rating) in meters are considered to be equivalent from the point of view of competition sailing. The difference in performance between yachts with different racing values ​​cannot be determined so reliably that they can sail against each other for a fee.

The formula proposed by Alfred Benzon was discussed in London in 1906 by representatives of the sailing federations of the great European nations. A representative of the USA was only present as an observer at his own request. It was necessary to agree on a replacement for the Godinet formula (Tonner formula) used in the Olympic sailing regattas and for the One-Ton-Cup . The Universal Rule (see J-Class ) proposed by Nathanael Herreshoff for the America's Cup in 1903 was largely rejected for political reasons. The adoption of the International Meter Rule and the binding promise to organize sailing regattas only with yachts according to this measurement regulation in the future led to the founding of the International Yacht Racing Union (IYRU) - initially without the USA. At the same time, the first sailing regulations were drawn up, which was actually the more important performance of the IYRU. The new formula and rules were first applied at the renowned regatta for the one-tonne cup with 6mR yachts on the Seine near Meulan-en-Yvelines , which the German Fritz Kirsten won and subsequently defended several times. At the Olympic Games in London in 1908 was agreed not to Godinet- but according to the meter formula sailed.

Since most sailing clubs quickly replaced their own regulations with the new, coherent and transparently communicated rules, they became a success. Internationally recognized measurement letters and generally recognized racing rules were introduced, as well as a serious system for organizing regatta sport. The measurement was carried out by classification societies such as Germanischer Lloyd . As an example of the popularity of the new meter classes, a series of articles in the former DSV magazine Die Yacht from 1913, in which the anchor equipment was presented using mR yachts, may serve.

Difference between bevel circumference and chain circumference

The meter formula today is as follows: (except 5.5mR class, see below)

Mean:

R - the racing value [m]

z. B. 8 m for an 8mR yacht

L - the measured length of the boat hull [m] measured at 1.5% of the racing value above the waterline

z. B. at 8 m × 1.5% = 12 cm above the waterline on an 8mR yacht. In addition, some difference dimensions that punish tricky lines are added

d - the difference between the bevel circumference (following the outer skin of the hull; English Skin Girth, SG) and chain circumference (English Chain Girth, CG) [m] (Fig. above)

measured in cross-section at 55% of the measurement length L from the front, from the intersection of deck / hull to a point in the middle of the ship at 12.5% ​​of the racing value below the waterline (for example 8 m × 12.5% ​​= 1.00 m for an 8mR -Yacht)

F - the height of the ship's side above the waterline [m] (freeboard)

here a kind of weighted and corrected mean value is taken from three measuring points: each at the ends of L and at 55% of its front end.

S - the measured sail area [m²] (Fig. Below)

LP does not play a role in determining the measured sail area for mR yachts.
the sum of the area of ​​the right-angled mainsail triangle (the actual area may be up to 25% larger due to the precisely regulated curvature of the leech) and 85% of the area of ​​the foresail triangle, which is also assumed to be right-angled . The areas of the spinnaker and gennaker are not directly included in the measured sail area, but their permissible sizes are limited depending on the shape and dimensions of the headsail triangle. The overlapping area of ​​the mainsail and headsail is also not included in the measurement. The latter freedom led to the "invention" of the genoa in 1926 on the occasion of a 6mR regatta in Genoa by an Italian sailmaker.

The meter formula essentially developed in three stages. In the first version from 1907 to 1920, the ship's width (taken from old merchant ship measurements) and the chain circumference from the Godinet formula were also taken over as speed-enhancing elements. Between 1920 and 1933 the width was omitted and the other dimensions were weighted slightly differently. Since 1933, the chain circumference has also been dispensed with and reweighted again. With the simplification of the formula, however, the determination of the measured values ​​became more complicated, for example which variants are to be considered when determining the upper measuring point for the height of the foresail triangle.

The meter formula for the 5.5mR class is different:

D - the displacement [m³]

S - the sail area [m²]

Sum of the area of ​​the mainsail and the area of ​​the largest foresail

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