Aug 30, 2017

Nacra 17MKII: Spi use Upwind allowed

Photo: - So yet another aspect of the new Nacra 17 MKII that affects the integrity of the platforms. It is clear that Olympic sailors push the limits of any equipment, but if you flatten spi design  on the new foiling speeds, plus the experience on the 2008 Olympics plus the use of gennakers upwind by the Flying Phantom Series Fleet for a while now, you have to wonder why the use of spis upwind in light winds was not foreseen by Nacra. One of the issues was that Nacra 17 MKII first spi versions were not flat enough to handle foiling speeds, as we pointed out here from just looking tests videos, and of course was also told by top riders to Nacra.

Still the Nacra 17 MKII seems to be a good platform overall, with solid and stable flights, bearing failures are being solved right now without much technical hassle aside the already mentioned money spent in flights , hotels and travel expenses on the delivery delays or the forced non sailing periods.

The Class mgmnt has discussed the use of spi upwind and have no rule or sailing instructions will made for coming Worlds at La Gran Motte, which to me is the right decision. Spi upwind should not be forbidden and sailors will need to asses the risks themselves.

Is like if in the F18 a full loose mainsheet works better for say 15knots downwind, now its your decision to put your mast at risk of breakage towards a speed or perf gain benefit. Nothing the Class or rules should do on such decisions.

Below an excerpt of the article pusblished today at Nacra 17 Class official web:
"...The counter argument is that the boat was not built to handle the loads of a gennaker upwind. The masts themselves are the original design and have not been redesigned to account for upwind gennaker sailing. To be effective, teams will need to flatten their mainsails by applying cunningham, which further stresses the masts. Using kites upwind will raise the average crew weights, a negative in a mixed class, and all the hardware would need to be reinforced and upgraded to handle the loads. Finally, the crews would need to act as human cleats, or cleats be added to the boats.

From a technical point of view, and Nacra have made explicitly clear, the mast is not designed to handle these loads. When it gets trimmed properly the mast loads are too high and the kite, pole, and the hardware components, are not rated for these loads either..."
Full text at