Stein,
I always considered the "semi-planing mode" to be akin to "a little bit pregnant"
In aerodynamics and hydrodynamics lengthening the object by adding a virtual object is possible, the aerospike rocket engine is using this principle very effectively, but it isn't happening with cat hulls. Look up aerospike rocket for more info.
For such a virtual hull to work it needs to excert a raised pressure onto the vertical stern itself. As in real life the sterns are only experiencing ambient airpressure it results that no vitual hull is effectively present. The theory of virtual hulls applied to cat hulls is now nothing more then fitting the errornous formula to "explain away" conflicting real life data.
I'm sorry.
Semi-planing mode seems to be accepted by all other boat designers. And it has nothing to do with pregnancy (I know, I have a medical degree).
The assumed "needs to excert a raised pressure onto the vertical stern itself" is irrelevant. Why should it?
Ask yourself: Why did the Int 14 sailors move the horizontal rudder wing to right below the water surface?
I think comparing the F16 with the F18 is a little bit unfair. The F18 is a very, very heavy boat, it is 70 % heavier than the F16 (180 kg vs 105 kg). The comparison proves that weight reduction IS important.
And that brings us back to the main theme of this thread....
However, I really do think F16 is a great class, Wouter.
Although I personally would have liked more sailors could enjoy the 19 foot, 140 kg Taipan 5.7.
Stein
