This page is totally about the design rules, download the rules for free from the Classemini.com site. See page Ratios if you want to know about Ratios and Performance and more statistics of the MT.
And about bowsprits and keeltypes, masts, etc.

The Serpentaire                  The Wylie design               The Berret design           The Finot design
Winner first Transat         First water ballasted        Carbon mast                     Beamy surf boat    
1977 Petit Dauphine        1979 American express   1985 Aquitaine               1991 GTM Enterprise

A brief development history:

         In the first race in 1977 the boats were production or home built cruisers like the Serpentaire, winner of the first race. Becausethe lack of suitable designs some sailors cut the bow away from boats to qualify the length limit.
         In 1979 the designs were more specific, as for instance the winner American Express. This boat carried water ballast, 280 lt. each side.
Then the development to the high performance was on.
IN 1981, double rudders. In 1985 Kevlar and Carbon. In 1991 we saw the canting keel now so familiar in the Vendee and the Around alone. In 1993 A-symmetricfoils.IN 1995 the beamness got bigger ending up in max beam and fast boats, canting keel and waterballast, like nr 198, a Magnen.  In 1999 the chines came into play, Lucas was the first one, nr 231 and 232.

The Open 6.5 class is a playground for designers who see their product really tested, for sailors with a modest budget to attract attention or reaching their dream. And recently (2003) the top of the bill campaigns are devolping, resultis a push for refinement. But they still get sometimes beaten by crapy boats with great sailors (Like Joschke, 2005-2006 on her Cape design beating a lot of new Manuards and others.). Top of insult is if you have an all tricked out carbon machine and you get passed by a polyester serie boat...

THE DESIGN RULES:

On this page I explain the rules, very basicly and it can get outdated by one meeting of the Classe Mini so check theofficial site for the rules, free available..
Attention; the French rules are the governing rules. See bottom of this page for more details about the complete rules.
"Characters in Italic are comments by me"

Sections on this page; hull, ballast, mast & poles, sails, stability

III - Hull Design
A mono hull is defined as a vessel having only one flotation plane when stationary, or with sails up insailing conditions, in which the depth of the hull in all its sections must not decrease in the direction of the axis of symmetry.
This means that a shape like a mono hull bow transforming in a catamaran stern is prohibited.

1. Length :

* The length of the hull must not exceed 6.50 metres. This dimension does not include rudders and their fixings, the fittings of the bowsprit bob stay (without devices intended to extend the length at waterline)as well as the solar panels, push pits, pulpits and wind vane pilot.

* The length of the hull is measured between the perpendicular of the bow and transom. The fore stays, the back stays, the shrouds (permanent or temporary) must be fixed inside the length of the hull..

* Bottom of keel to top of the highest sail = 14 metres maximum

* Max. draught : 2 metres, regardless of the angle of heel and the position of appendices or mobile appendices.

* The booms may not extend beyond the transom with the mainsail up at full hoist

* The cockpit floor must be 15 cm minimum above the waterline.

* Max. beam : 3 metres including mobile keels and masts and rigging.
(Too when using a swing mast.)

* Average freeboard : 0.75 m minimum (the measurement of this will include the number of points required to know precisely the real average freeboard).

* A cabin top is mandatory with minimum volume calculated as follows :Cabin top volume (m3) / minimum = Beam MAX. (in metres) /6

* Deck camber : the minimum positive rise measured in any part of thedeck must be equal to :Rise (in metres) = beam (in metres) x 0.05"Rule of Pythagorean comes handy"

* Ballast is allowed if they are fixed, located inside the hull and part of thestructure of the boat. The total volume of water ballast must not exceed 400 litres symmetrically displaced along the longitudinal axis of the boat. Their use must not compromise the ability of the boat to right itself. The vents for each ballast must be located on the deck and have a minimum inside diameter of 25 millimetres. Each vent must have a cap.
"This means 200 Lt a side of saltwater 1.024 kg/ltr "

* Bulb :The height and width of the bulb on the keel must not exceed 450 mm.
* Materials : materials with a density greater than lead are prohibited. Titanium is forbidden, Carbon is forbidden in the masts.

* Bowsprit and spinnaker pole :The bowsprits must be quickly and easily removed whilst sailing without tools, also that all components outside the vertical of the deck line (except the boom). A tolerance of 30 mm is allowed.Bowsprits and their associated hardware must rest in the rule limit of beam (3 metre maximum).

* Mast : They must be made of extruded aluminium with a weight of 2 kg/m minimum or out of Carbon, no limits. Tapering is allowed above the upper spreader.If mast area is more then 2.2 m² then it counts as a sail.

* Shrouds, lowers and fore stay : stainless steel rod or wire. Titanium is forbidden.

* Sails : The number of approved sails carried on board must not exceed eight (8). This must include a storm jib of maximum area 4m2, reef able to 2.5m2, and a try sail of 5m2 maximum area of a fluorescent colour and a minimum weight of 340 g/m2.

* Material Sails (EXPECT BIG CHANGE IN 2008 RULES)
* Mainsail : woven polyester, with windows of 0.2m2 maximum area.* Head sail : woven polyester and polyester film
* (Head sails in 3DL are permitted but only in polyester -this was a ruling made in February 1997)* Spinnaker : nylon
*Double film sails count as 2 sails. A wing mast of more than 2m2 in projected area counts as one sail, as well as any other wind propulsion system. See article I-11 for the sail number rule.

For MORE bowsprit PHOTO'S, click here.

2. Stability :2.1 Large angles stability : The boat, while empty except for batteries and the life raft, and with all hatches open, must not permit water flooding and must havepositive stability with a 45 kg weight at the top of the mast in the most unfavourable ballast and mobile keel configuration and masts (not including the Archimedes effect).
The stability test is effected with the head of the mast at water level with full ballast on one side then on the other side.

 Small angles stability :

The boat while empty except for batteries and the life raft,must not exceed a 10 degree heel angle in the most unfavourable ballast, mobile keel and mast configuration."so with a canting keel it means that how heavier the bulb or how more it cants the boat has to have more resistance against heel, a stiff (wide) boat is the result.

WARNING:
This is a resume and it is explained with drawings for ease of understanding.
 And is not the most current (keep changing it since 1998, to much owk to detail all, do not trust this info for designing :) ). Get them at the Official Classe Mini, check the official website.