Pardon my french here but what a non-informative post that turned out to be. Look at it was stated :
A Nacra Formula 20 CB is the centerboard version of the F20 boat
that is based on their new F18.
Both info elements in this sentence are just plain non-sense. It was actually just a centreboard version on the Nacra 5.8; that is even reflected in its name. It DOES NOT comply with F20 rules; it is not heavy enough. So that info element was non-sense as well.
The hull shapes are very similar to
the newer Nacra F18 but a bit larger.
Not really, the hullshapes are more like the old nacra's; the N5.2's, N5.5's, N5.8's and even N5.7's, then the nacra F18.
They are narrow, have a very
fine entry, tall plumb bows,
What is narrow on a catamaran. I think the hulls to be rather medium in the way of narrowness. And it doesn't have a plumb bow like the Inters. Tall ? Well the Nacra F18 has tall bows the nacra 580 doesn't. At least not more then its predessor 5.8 and other nacra boats of that time frame.
and a super-cool ultra thin walled
chromium-alloy (chromolly) super strong and lightweight mast that
has better flex characteristics than other current aluminum or
carbon fiber masts.
Right ! All other designers are still using wooden masts on their boats right ? And clearly carbon wing masts are inferiour to this pretty standard tear drop shaped mast. Talking up your product is one thing but still is more then a little over the top is it not ?
The centerboards are high aspect ratio
The N580 centreboards have an aspect ratio of 2 (the width fits 2 times in the wetted length); see provide pics.
As comparison :
F18's daggers aspect ratio are between 3 and 4. Nearly double that of the N580.
A-cats daggers are close to ratio of 4.
Even the old Nacra 5.8 (predessor) had a daggerboard aspect ratio of 2.4 = 20 % more then the new one.
But we call these new dagger "high aspect ratio" !
When the boards are lifted half way up, they
swing so far aft that the center of lateral resistance is moved
significanlty aft and thus provides a superior resistance to
broaching.
Please all catamaran sailors that suffer broaching on their boat raise their hands.
No-one ?
Ofcourse broaching is a monohull problem. It is linked to the heeling of the boat and the weatherhelm that is caused by the centre of effort being suddenly moved far out of line to the single daggerboard as a result.
I rest my case now.
Wouter
