Actually I was only saying how the newest version of the Nacra 17 design; the EU variant of the F17 which is different from the US F17 variant, is closely resembling the F16 specs.

But I have to correct one error on my side. The F17 hulls are 0.25 mtr (=10 inches) longer instead of only 0.20 mtr (=8 inches).


However what is more interesting is the almost panick like reaction to my claim that several Nacra 17's were measured to be around 135 kg when fully rigged. In itself an attractive spec. The opposition seems to strongly favour the number 159 kg. I honestly couldn't figure out why this is.

That is till I checked up on the measurement of the EU F17 version at the F104 webblog. The specs were there given as :

source : http://class104.over-blog.org/pages/Mesures_des_principeaux_104-33825.html


Weight ready to sail : 159 kg
length : 5.25 mtr.
width : 2.5 mtr.
Mainsail area : 15.34 sq. mtr.
Luff length : 8.69 mtr.
Jib area : 3.75 mtr.
Jib Luff : 5.34 mtr.
Spi area : 18.98 sq. mtr.
Daggerboard area : 0.16 sq. mtr.
Daggerboard luff : 0.8 mtr

SCHRS rating : 1.035 (= F104)


However when I punch in a weight of 158.7 kg, 300 grams (2/3rd of lbs) lighter then the acclaimed 159 kg then the rating drops below 1.035 and the F17 EU version is no longer a F104 !

That would allow any F104 result by the F17 EU version to be protested and disqualified. Punch in the 135 kg and the rating ends up at SCHRS = 1.009

Note how the F16 SCHRS rating = 1.008 and the F16 has the following specs :


Weight ready to sail : 107 kg (measurements of 2007/2008 boats show 105 - 112 kg)
length : 5.00 mtr.
width : 2.5 mtr.
Mainsail area : 15.00 sq. mtr.
Luff length : 8.10 mtr.
Jib area : 3.70 mtr.
Jib Luff : 5.45 mtr.
Spi area : 17.50 sq. mtr.
Daggerboard area : 0.16 sq. mtr.
Daggerboard luff : 0.75 mtr

SCHRS rating : 1.008 (= NOT F104)


Note how the previous (7) versions of the Nacra 17's have moved through the specs :

Mainsail area : 13.68 sq. mtr -> 16.44 sq. mtr. -> 15.34 sq. mtr. .... = now 102% of F16
Jib area : 3.40 sq. mtr -> 3.75 sq. mtr. .... = now 101 % of F16
Jib luff : 5.00 mtr -> 5.35 mtr .... = now 97% of F16
Daggerboard area : 0.199 sq. mtr -> 0.16 sq. mtr .... = now 100% of F16
Daggerboard depth : 0.982 mtr -> 0.80 .... = now on average 103% of F16

(All less then 3% differences)


And notice the path taken by the naming : Inter 17 -> Inter 17R -> Nacra 17 -> Nacra F17 -> F17


The only differing specs remaining are.

Hull length : 0.25 mtr => 105% of F16
Mainsail luff : 0.59 mtr => 107% of F16
Mast length : 0.55 mtr => 106% of F16
Spi are : 1.5 sq. mtr. => 109% of F16

(all less then 10% differences)

and

Weight : Claimed by Nacra 52 kg => 149 % of F16
Weight : Claimed by Wouter 25-30 kg => on average 126% of F16


Anybody else noticing the similarities ? And the exceptional offset of the ready to sail weight compared to all the other specs ? I distinctly remember being rediculed on this very forum back in 2002/2003 when I claimed the I-17 boards were to large and too long for a singlehanded boat. Turns out the designers have come to agree with me as they have reduced the nacra 17 boards in area by 25% and in length by 20% to arrive at almost smack identical dimensions as the average F16 board !


Coming from the US Inter-17R design where the differences to the F16's were typically in the range of 10%-30% depending on the spec analysed we have converged to a situation where all the specs except weight are less then 10% with 5 out of 9 items are different by 3% or less !

I call that convergence. And since the F16 class has remained the same in its specs since 2003 (when 14.85 sq. mtr mainsail area was rounded off to 15.00 sq. mtr) it must be that the Nacra 17 design is converging to the F16 specs and I don't think that coincidence can be blamed for that.


Actually I never claimed superiority of the F16 class per se, I only claimed (and have done so for many years) that the F16 class is reflecting an optimal point in catamaran design that is hard to beat; hence the equality in performance between it and the F18 class and the fact that F18's shame so many ultimate all-carbon design in regatta's. Of course this situation is determined by a given set of a few basic design choices. One of which is the 1-up/2-up versatility, this limits the amount of mainsail area and board area as these need to be such that the boat still works well for a singlehanded crew. Another is the choice to have the boat trailer horizontally within a world wide legal limit (2.5 mtr). It seems that the evolution of the Nacra 17 design is finding the same optimal point (of specs).

Personally I think this to be great. Mostly because the Nacra 17's that are around 135 kg (and have SCHRS = 1.009) can now level race F18's (SCHRS = 1.005) and F16's (SCHRS = 1.008); first over the line wins.

Maybe we should forget about this F104 class and form a F101 (= Level F18 ) class instead ?

And I must admit that I find the new EU version of the F17 specs (except the overall acclaimed weight) alot more attractive from a sailors perspective. I'm convinced this variant will behave very well as it appears the balance between the specs is better then before. Especially for a solo sailor.

Wouter