Todd... I think that your definition is simply your take on it.

The limitations that you think makes for a formula vs box rule are better described as class rules... similar to the no electronics rules that classes may choose.

The larger sailing community assumes formula class means a mathematical equation which is the design rule. Those rules give you boats with a certain look. The goal was to work within the formula and come up with the fastest design. See 12 meter AC cup rules.

Then you have classes that form around some sort of RATING Rule... The idea being that boats designed to the rating would be one design in performance but have slightly different choices for the owners.

I have never heard of an F18 Formula... much less seen the math.

My read of the F18 history was that they had a Box in mind... 18 feet and max beam of 8'6 inches and 400 or so pounds. They also wanted the largest crew weight optimum and so they wanted one platform with two sail plans for crew weights. They had strong opinions on what the class rules must be so that they could stay independent of the major builders and continue with development in a controlled manner to preserve an owners value over time. So... the A class and C Class are simple box rules... (remember the Tornado is a B class boat) The F18 is a more complex box rule with many restrictions. A one design class is the most restrictive box of all...and in the end... they simply don't allow anything they did not build... even if it were identical.

I am pretty sure the Formula simply refers to the crew weight Formula they use AND to brand the class as distinct from the Hobie Tiger, Nacra inter 18 and Dart Hawk one design classes they were sucking in and to distingish the class from classes run by the builders. Remember, these one design classes had one sail plan and minimum crew weights to go along with the manufacturer only equipment restrictions.

The F16 class debated the alternate sail plan idea as part of the basis of their Formula for their F16 Box. ... They nixed the idea because the EU opinion was that the two sail plans did not live up to the billing (sorry JW). Their formula was the pretext that that by dropping the jib and hardware they would equalize one up and two up racing... with first across the line wins... They justified this assertion by computing the texel rating formulae and noting the slight differences should be fair around the race course. Again... this is NOT a formula class... rather a box rule with restrictions... (of course some would argue... not enough restrictions but that dog has been quiet lately)

Kris, My solution... explain the classes called Formula as crew weight formulas added to a box rule with nothing to do with design rules. Most big boat sailors are not that familiar with box rule classes either and so the general confusion with formula rules, rating formula classes and box rule big boat classes is just too deep . The simple solution is understandable and handles the real issue. Will my boat choice be obsolete tomorrow and in 5 years. ...