I fail to see any relevance between the minimum weight of the F16 formula “box rule” and the respective individual weights of the boats actually out there sailing that fall within that box rule.
IF, the F16 “class” of catamarans were a ONE DESIGN class, then yes the minimum weight would have a much greater significance, as most, if not all those cats would probably be “manufactured” by one “professional” builder and that minimum weight would/should be the consistent weight of each and every boat produced by that manufacturer.
BUT THE F16 IS NOT A ONE DESIGN CLASS. Its dimensions are bound by its box rule formula, whereby each cat eligible to compete within that class has only to fall within the maximum and the minimum dimensions of that box rule. The cats eligible to compete within this “class” can be built by ANYONE, and as such they will obviously vary in many different ways from one to another, and as long as they all still fall within the “box rule” (no matter who builds them or what their relative shapes) there should be no problem (or argument) As far as the minimum weight is concerned, it is one of the dimensions that is an objective to be achieved and if some boats at present do not get down to that weight then what does it really matter – some do weigh the minimum! – And more will as the class matures. It is not really a question of “why are some boats overweight” but more of not having the problem of boats regularly being sailed under weight and trying to compete below that weight without penalty. The minimum weight is a goal that is, at this time, not universally achieved, but like many classes before where many cats within those classes did not come in at their minimum allowable weight, over time they all did.
The Mosquito in Australia, which is a one design class of cat that is an “association defined” class (similar in many ways to the formula concept), for many years were all built “overweight” but for some years now they have all managed to be built at or below minimum weight and need to carry “correctors” to ensure that they fall within their allowable weight. During the 1970’s there was this same argument within the mosquito association that the minimum weights should be raised to “make it fairer for all the – heavy – boats, to compete”. They are all glad now that decision wasn’t taken.