Not sure MARY, but if you were to allow trimarans or tri foilers or triple hulled planners or hydrofoiled craft, it all starts to get a little out of control. I don't think any one would object to allowing "normal" monohulls compete with F14 cats, because they would automatically think that it was a pointless exercise for the mono hull sailor, (and it would be) but when it got down to allowing a radically different "type" of craft that would have entirely different sailing characteristics (and probably a far superiour performance) the line would very quickly be drawn. Besides the interest here is for a formula 14' CATAMARAN (ie two hulls of equal volume). If you want a formula for "every thing" then create one, but I think that this one is, rightly or wrongly for "catamarans".