Nacra 15 FCS for fun

[martin 'hoff]

In a moment either deeply wise or stupid, I made a move on a N15 FCS that was available ex-demo for a price I liked.

There's a separate thread where I posted about my adventures on a red Whisper. That boat is now for sale (with brand new sails and various upgrades https://sailinganarchy.com/advert/whiteformula-whisper-foiling-catamaran/ ) . And we're getting onto the new challenge.

From what I see, there's a handful of non-olympic pathway sailors sailing N15s; some in the "Nacra 15 FCS One" configuration (optimized for soloing – has a decksweeper for lower CoE, and a different kite halyard setup), some in the standard config. So I guess that's my track, I'm too grown for the N15 competitions.

Anyway, are there any N15 sailors reading this forum? It'd be great to trade notes.

At this point, we're only getting started and finding that the boat can be pretty powered up. Intent is to sail it for fun, occasional local races, and perhaps try to pace the proper N15/N17 fleets when they are in town. Soloing (~80Kg), two up with my 10yo kid, or just 2 adults.

• The manual is a bit skimpy on rigging setup. Are there better descriptions of rigging setup, and variants? I'm keen to see how the halyard runs in the One configuration. Keen to see how the cunningham is setup – apparently on N17 the skipper actively the cunningham to depower.
  
• What foil rakes are people using? We're on the standard rudder rake, and between 2 and 3 for initial skimming/foiling.
  
• "Walk the boat" technique – we used to walk the boat on the Whisper to get it flying and then to help control flight. On this boat, we need to up that game 100x, any tips on technique welcome. 
  
• Protective gear? (ie: kevlar wetsuits for kids?)
  

If you are wondering, the boat is a complete hoot, and can be a handful. Took the boat out on its second foiling outing with 12kt gusting 16kt and a bit of chop, and that was premature. I expected as much, and took an adult instead of the kid. In breeze, boat is pretty powered up and we flew out of waves (stuck the bows a bit, etc).

 

[martin 'hoff]

 

[martin 'hoff]

One more question: I know I've seen a variant of the N17 FCS setup, with lines running outside of the main crossbeam, a knot on the line, and a "rake grading" sticker, so you could look at the crossbeam and know what rake each foil has. 

Cannot recall where I saw this -- may have been on the boatpark here in Miami. 

Does anyone have a diagram of how that layout runs? 

 

[martin 'hoff]

Ok, so there's a video series by Thomas Zajac – shot in Montevideo – which has elements I don't enjoy (Thomas appears rather blase about people's safety) but has a ton of onboard headcam footage, showing Thomas' setup up-close.

https://www.youtube.com/watch?v=PF6tSn_t2aw

At 9:26 you can see a good clear shot of the rake gauge setup. Cunningham line goes to the crew's trapeze. Jibsheet goes to shouds. 

 

[F18 Sailor]

Congrats on the new boat!

Not sure how much is out there regarding rigging for these boats if you don’t talk to the owners first hand. The DNA A-Cat has similar board markings rigged as part of their system. I believe it is simply a knot tied into the board control line. 
 

This video just came across my desk and may help: 

 

[martin 'hoff]

In https://www.youtube.com/watch?v=0PqIy26s7K8 at 1:18 a good shot of cunningham trim markers on the mast, as well as the foil rake marks.

You can also see +/- signage on the trampoline to make it clear which rope to pull to increase/decrease foil rake.

 

[martin 'hoff]

10 minutes ago, samc99us said:

Congrats on the new boat!

Not sure how much is out there regarding rigging for these boats if you don’t talk to the owners first hand. The DNA A-Cat has similar board markings rigged as part of their system. I believe it is simply a knot tied into the board control line. 
 

This video just came across my desk and may help: 

Thank you @samc99us! - so this is a bit more complicated! interesting. Instead of running takeups under the tramp, or inside the rear crossbeam, they go alongside the rear crossbeam -- that's... unexpected. 

I'm intrigued by the markings and numbers on the boom. Can't see what they are measuring there. Also, the cunningham trim markers have a much narrower band than Zajac's. 

The foil rake trim markers are doubled up -- both foils are visible on both sides of the crossbeam. 

Foil rake lines offering a single line but having it bi-directional is definitely an improvement. 

 

[F18 Sailor]

The boom markings are outhaul, almost guaranteed. The back set is for the skipper to quickly visualize, front set are for the crew to fine tune as they have a 2:1 lead. 

I am also surprised that everything is pretty much above the tramp with a few exceptions. The aero drag delta for that is minuscule compared with the penalty for tripping over a line!

Do take note of the heavy use of ceramics and stainless blocks. I have a great ceramic mainsheet option that isn’t nearly as pricey as the Harken; the downside is the ratchet setup relies on an external block, easily managed on an A with center sheeting, a bit more trouble for rear sheeted boats but doable.

 

[F18 Sailor]

Turns out the forward boom markings are mainsheet trim indicators.

 

[martin 'hoff]

Turns out the forward boom markings are mainsheet trim indicators.

How does that work?...

The loads on N15 seem to be lower. More run-of-the-mill blocks. Also, other N17s in videos have shockblocks/sheaves and less sophisticated stuff. That's a Harken promo video, so every chance to use a cool block has been taken

 

[martin 'hoff]

Sneaked a short outing today. Smooth sailing with Alessandro at the helm. 10kt gusting 14kt. 

Our short outings are on a narrow spot so no chance for a good deep spinnaker run. The kite power on a reach is hard to handle (at least now, for us) and I don't think we had that situation under control. We're using to having a footstrap for the helm; without it we felt vulnerable. 

Rake 2-3. Main started out depowered, but as we found our stride I powered it up. In these winds upwind foiling vs non-foiling difference was 30 degrees. On our first outing with more wind, it looked like we could do pretty nicely foiling upwind -- footing perhaps 10 degrees.

 

[martin 'hoff]

Gear -- aiming to get

• footstraps -- 1 pair initially, perhaps a second pair later
  
• helmets
  
• kevlar gloves (as per the WS report from Bora's accident)
  
• kevlar wetsuit
  

(I recently took an acquaintance out sailing on a different foiler, and in a moment of distraction he got cut. This boat's foils are "inboard" which is really good, but they are sharp...)

 

[martin 'hoff]

https://nacra17.org/on-hyperspeed-woman-overboard-and-the-meaning-of-steep-learning-curve/

 

[Phat Buoy]

Do take note of the heavy use of ceramics and stainless blocks. I have a great ceramic mainsheet option that isn’t nearly as pricey as the Harken; the downside is the ratchet setup relies on an external block, easily managed on an A with center sheeting, a bit more trouble for rear sheeted boats but doable.

Apologies for the thread hijack, but I'm in the process of going DS on my A.  What is this ceramic mainsheet option of which you speak?

 

[martin 'hoff]

Apologies for the thread hijack, but I'm in the process of going DS on my A.  What is this ceramic mainsheet option of which you speak?

High end blocks for 10:1 and higher purchases, used on N17. The mainsheet itself is dyneema core...

 

[F18 Sailor]

Martin,

  Yes and no. Harken have their GP mainsheet system, specifically designed for the Nacra 17 and to some extent the F18. It is a nice solution with integrated auto ratchet. I am working with another company on a simpler, less expensive system. The cascade is more like the 8:1 and 10:1 systems of old, and the ratchet is external. We have it on one A-Cat here and it is working great! Phat Buoy, PM sent.

 

[NacramanUK]

Harken video about the GP mainsheet system.

 https://www.youtube.com/watch?v=h3nxd4ftUWg

 

[SimonN]

Martin

Congrats on the new boat. Settings are one thing, but as you have discovered and implied, sailing technique is where it is at and there are some things that aren't so obvious. What is obvious is that there is no wand, which used to help by managing flight height changes with a given set of settings, so that for any crew weight position and sail time, it make adjustments to the ride height when it changed so you didn't need to. Now, everything is up to you. This means you are constantly moving, constantly sheeting and constantly steering.

The key to this game is to stop thinking about trimming your sails in a conventional way. The sails are your height control. Load the sails (pull in) and this loads the foils and the boat reduces ride height. Ease the sails and the foils unload and ride height increases. That's the basics. So consider sailing with the kite up. Should you be sheeting for proper airflow and power, or should you be sheeting to control the amount of load on the foils and therefore the ride height. The simple answer is the latter, while the long answer is that it is the latter combined with walking the gunwale and steering. But that's getting into advanced territory. To start with, practice ride height control through sail loading (assuming you are standing in about the right place). Once you get the hang of that, combine it with walking the side so that you can reduce the amount of sheeting a bit and maintain as good flow over all the sails as possible and finally, combine it with steering.

 

[martin 'hoff]

@SimonN - spot on. Yes, this is a bit more like an a-cat that we should actively use pressure on the rig to control ride height. We were already doing some of that on the Whisper, so not entirely new. It's also fairly different in particular in the downwinds – you can't play the kite as you play the main, and the heat up/soak dynamic also plays into the ride height. 

It's a strange game I'm still wrapping my head around. When you bear away with speed, that pushes the boat down (more pressure from the rig, down on the foils), and the bow a bit down (more leverage forward top of mast) and depending where you are on the wave sequence, if you walk astern on the boat you might punch through the next wave top, or dig the bows and go for a spectacular flight.

If you're about to plant it in a trough, what's the maneuver? Here's my current thinking: head up (heat up) will increase speed, reduce pressure down and leverage from top of mast will move from forward - bow down - to heeling. So the boat will pop up, point bow up, and heel. Uncontrolled/abrupt, this will result in the typical "rearing horse" moment followed by stalling the foils and splashdown. But if the helm heads up subtly and the crew walks forward and stretches out (for leverage on the wire)... well, you gotta get the timing and dynamics right but it should: increase speed, reduce downward pressure (boat rides a bit higher), crew forward drives counterbalances nose up-tendency, crew out (and ease of main?) counteracts heeling, and finally (assuming waves aligned with the wind) the hotter angle means a longer wave length so better chance to save it from a nosedive.

Is this reasonable? Other takes on the downwind sequence?

We took part in a long distance race yesterday (mixed fleet). We did really well while mast-up ;-) -- on handicap time, roughly speaking we lost by the time spent capsized. Footing slightly, we'd do stretches of ~10-12kt upwind. We only did about half of the downwind leg with good speed – we're still figuring this puppy out – but when we did, we we smoking. Big swells and long distance so limited foiling.