ASYMMETRIC SPINNAKER A2 + SNUFFER

Property

QTY

DESCRIPTION

NorLon150 (1.5 oz)

MANUFACTURER

North Sails

URL

MEDIA

Color Code | North Sails

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www.northsails.com

Note: Incidence - 211 sqm triadial cut nylon spinnaker+ sock

SAGA - O55#1 - ASYMMETRICAL SPINNAKER

The ability to get good VMG downwind is the most important thing in blue water sailing. It was 50% of the time on Moby (2594 hours!)
We spent hours with Fred and Steve from Technique Voile, trying to figure out the best downwind sails combination, from a cruising standpoint (NOT racing). They used boat VPP (Velocity Prediction Program - cruising corrected) and they came to the conclusion that we were facing a challenge to get good VMG in TWS 10-15KTS range.
A2 - The recommendation was for an asymmetrical spinnaker. I had initially some concerns, based on the drawbacks of Moby’s asymmetrical spinnaker from Incidence but they managed to convinced me that the behavior of their spi would be very different!

They use a very flat cut to be at the same time tolerant to big AWA changes as we often experience when the boat accelerates down a wave, and able to be used down to 160° TWA when the tack is moved towards the windward bow. We’ve only tested it 2 times, but I was impressed by the performance achieved downwind and the sail stability. This spinnaker can be used up to 20-max25 knots TWS.
The VMG gain, compared to the figures I have in mind from the 51, is up about 20%. I hope more testing in different conditions will confirm this!
Needless to say that it is paramount, when handling this size of spinnaker shorthanded, the downline must be well set-up to facilitate the maneuver. This point is on my job-list when I take delivery of the boat.

A4? Spinnaker: It is possible that we decide to get an extra sail for downwind VMG in 20-30 knots.

Next summer, we will try different types of smaller spinnaker, symmetrical and asymmetrical and decide if we need it or not.

FEEDBACK FROM SAGA

Pour le spi, un A2 c'est bien, on l'utilise jusqu'à 20 noeuds de vent.
Stability

A comparer avec celui que nous avions sur notre 51. Et aussi avec celui de GreatCircle.

Asymmetrical Spinnaker

We've tested the spinnaker for 40 minutes, with and without the staysail in winds from 12 to 16 knots. This asymmetrical spinnaker has been designed for downwind VMG.
We tried various TWA between 110 and 165 and the sail was incredibly stable, even though we had residual choppy seas.

Bear in mind the instruments have not yet been perfectly calibrated, the TWS over-reads, as well as the boat speed
And the TWA also need to be calibrated for the huge angle shift created by the square-top mainsail beyond 140°TWA.

Speed-wise, at 130°-140° we had a SOG slightly less than the indicated TWS.
Sailing deeper, the VMG feeling was excellent and definitely better than the 51 in the same conditions.
Anyway, I couldn't be happier with this asymmetrical spinnaker. I knew the good reputation of Technique Voile for their spinnakers and now I understand why!
The importance for a downwind sail on catamaran is the stability to be able to cope with the boat acceleration without collapsing. We still have to test the asymmetrical spinnaker in typical oceanic conditions, but from what I've seen on Monday, I am confident it will be ok!
The gain I expect in term of VMG with the asymmetrical spinnaker is about 10% of VMG at least. There is no miracle downwind, the more sail area gives the more VMG, everything being otherwise equal.
A smaller symmetrical spinnaker will be a good sail for downwind in winds above 18-20 knots, on the 55 you could then expect a VMG slightly below 50% of TWS and a comfortable ride. The issue with a symmetrical spinnaker is when you try to get good VMG downwind in winds below 16-18 knots.

Wind

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