Posted: Dec 20, 2012 - 11:52 PM
This may be some of the same.
Tuning the Nacra 6.0NA
By JAMIE DIAMOND
Where to start? We set up the boat according to Mark Biggers in the spring of
1994 when we bought the thing and essentially haven't changed any of the rigging
since then. We had a successful Nacra Mid-Winters this year, so Mary Wells asked
me to write an article on tuning the 6.0. Well, I'm way late, but here it is.
Setting up the boat
The platform: The hulls, the boards, the rudders are all perfectly parallel with
the mast down (no rig tension). The forward beam has about 1/2 inch of pre-bend.
The bridle foil has more.
We used self-stick Velcro to pad the daggerboard trunks so that the daggerboard
don't slop around in the trunks.
The mast
About 2 inches of pre-bend, with about 2 inches of spreader rake (distance
between a ruler placed across both spreaders and the luff track on the mast).
My outer diamonds on the mast are under about 700 lbs. tension. The inner
diamonds are just snugged up but not adding any more mast bend.
I copied my mast rake from Andy Zitkus at Bay Week a couple of years ago. I
don't know what it is; I only know I use the 2nd hole from the top of the
chainplate for the forestay and the 4th hole from the top of the chainplates on
the sides for the shrouds.
I believe having all your wet stuff lined up straight is important. I'm not so
sure about the pre-bend in the mast, tautness of the rig, and mast rake.
However, I do believe that to be successful, you must set this stuff, and then
leave it alone. Sailing a boat fast requires a lot of helm "feel." Unless you
are Randy Smyth, Kirk Newkirk, or Carlton Tucker, you won't get there very fast
if you keep changing the boat around. Set the boat up the same way each time and
start practicing, developing that helm-feel you need to be fast.
Sailing the boat
Mainsail
You've got more controls on the mainsail than I know what to do with --
downhaul, mainsheet, clew traveler, and main traveler.
The downhaul
Before you go out on the water, you need to find the "power-position." This is
the amount of downhaul where you have maximum pocket in your mainsail. Many
people think they get maximum pocket with the downhaul completely eased. Not
true!
Get the boat rigged up. Lie on your back on the center of the tramp with your
head near the base of the mast. Sheet the main until the boat is trimmed for
going to weather. Now start applying downhaul. As you tighten the downhaul, you
will see the pocket first increase, then decrease again as you pass the
"power-position." Go back and forth a few times past the point until you are
sure where it is. Then mark your mast where the pulley plate of your mainsail is
at the power-position. This is where you will downhaul for upwind until you are
overpowered. Once you are overpowered you will downhaul beyond this point. This
is also where you will set the downhaul for downwind. You will never want to
sail the boat with the downhaul looser than the power-position.
The clew traveler
Upwind I set my clew traveler with its center 1 to 2 inches behind the bolt in
the center of the clew traveler track. Downwind, if it's a long leg or light
air, I'll blow off the clew traveler letting it go all the way to the back. If
it's cranked up, or the legs of the course are short, I'll ignore this control
-- just set it for upwind and forget it.
The main traveler
Upwind I almost always center it. I deal with the big wind with the downhaul.
Off the wind I usually ease the main traveler to somewhere near the hiking
straps. This one is tough to call and varies a lot with wind conditions. Finding
the sweet spot where the main traveler and mainsheet are both set right for
wild-thinging downwind is tough. And it varies with the wind, the waves, and the
crew weight.
The mainsheet
I usually get to sail in flat water. So going to weather we sheet the main hard,
really hard. I want almost zero twist. If it's double-trapped or more, the main
is usually sheeted as hard as I physically can, both hands. If we're in waves, I
back off some. When the boat is pitching, you want some twist in the main. It
helps keep the top half of the main from stalling on the backward swing of the
pitch.
On the downwind leg, travel out, but probably sheet harder than you are. You
need some firmness in the leech to do the wild thing. Play with different sheet
and traveler combinations until the boat jumps. Then look around at the waves
and wind speed. Remember it for the next time.
Jib
Sheet it harder than you think. If there's any sizable breeze, I put the jib
cars all the way back, and fairly far out. The stronger my foredeck crew is, the
farther out they go. At MidWinters, with Mike Teets up front, we ran the jib
cars all the way back, and the jib block was about one hand width from the hull.
This lets the crew sheet really, really hard without closing up the slot. Give
it a fair bit of luff tension, too. The flatter the luff, the higher you can
point, but the less power you have, and the harder it is to keep the boat in the
groove. Find a happy medium.
On the downwind I set the barber haulers all the way out and sheet the jib
fairly firm but not hard, maybe a foot to foot and a half between the barber
hauler and the jib clew plate. If you've got the luff tension cranked up,
consider backing it off. Ignore the luff tension on the downwind if it's a short
course and things are busy.
Mast rotator
Sometimes I use it upwind, sometimes I don't. No real method to the madness.
Downwind, use it. Rotate the mast 90 degrees. If it's really windy, or you're on
a short course, this is another control to ignore. You'll gain more distance in
the time you're sailing the boat instead of pulling the strings than you will
lose in boat speed.
Daggerboards
All the way down upwind, halfway up downwind. If you're on a short course, put
them down and ignore them. Never sail the boat with them all the way up. And the
ligher the wind, the more daggerboard you need. Just the reverse of what a lot
of folks think.
Crew is key
The most overlooked key to winning is the crew. I believe this is true on any
boat. My key to speed at Mid-Winters was Mike Teets. He ran everything on the
boat from the daggerboards forward. And he called all the marks, laylines,
crosses, and ducks. My sole job on the back of the boat was to make it go fast.
I played the main, steered the boat, and got my head out of the boat, looking at
the wind and waves out in front. I never had to look over my shoulder for a
mark, or behind to see what the competition was doing. That was Mike's job. By
concentrating solely on boat speed, I had a boat-speed advantage. And a
boat-speed advantage made Mike's job of calling the tactics easier.
Try it next regatta -- when your crew says to tack, don't check their work, just
do it. When they realize that it's all up to them, they will quickly grow into
the task.
Good luck, and sail fast.
--
Ron
Nacra F18
Reservoir Sailing Assn.
Brandon, Mississippi
--