6.0 NORTH AMERICAN
Special Report
Approved by Performance Catamarans
Tuning The 6.0 N.A.
by Jim Downs 6.0 NA Champion & Mark Biggers
StartingPoint:Hull Alignment
Since all NA’s are brand new (out of the box), start with
the front crossbeam and set the hulls at the stops. Set the rear
beam in the saddle & adjust the the movable stops to allow
the hulls to be aligned. The NA tramp is designed to tension only
from the rear beam by shimming the stops at the front beam. Set
the alignment so there is no toe in or out. Since the NA has a
front foil instead of the bridle wire, alignment does not change
with the rig up.
Rudder Alignment
Rudder alignment should be set to 0 or 1/32” toe in to
compensate for lash in the rudder system. Set the rudders after
the tramp is installed and tensioned to make sure the hulls are
in final position. With the sleek hull shape of the NA rudder
alignment becomes even more critical than on other boats.
Daggerboard Tuning
NA Daggerboards and rudders are the same as those of the 5.8 so
careful tuning is important to prevent cavitation. Rounding of
the leading edge seems to be more important than getting the
trailing edge sharp. For the trailing edge, thinning of the foil
from about 1”-2” forward to an edge about 1/16”
thick seems to work best.
Mast Set-up
Set the spreader rake to about a minimum of 2”.(Place a
straight edge across the tips of the spreaders and measure to the
back edge of the mast) With the double diamond wire system of the
NA mast, it is important to use a wire tension gage to set the
tension of the diamond wires. Start with the outer diamonds and
set tension to about 500 lb. this should result in the mast being
pre-bent about 13/4”. Then set the inner diamonds to be just
tight but not enough to increase pre-bend.
Bridle Foil
The front foil should be tensioned to pre bend about 1-1/2”
new and not allowed to relax to less than 1” of pre bend
after the rigging has settled. This has no effect on speed and is
strictly a strength or durabilty requirement.
Rig Set-up
We tried several positions of mast rake and found that about 15”to18”
of rake seems to be fast upwind without creating excessive rudder
load or de-powering the boat. We measure rake by pulling the
trapese harness hook down and moving it to the point where it
just touches the top of the deck forward and aft of the front
beam. Then measure the distance from the center of these two
points to the front of the front beam. Shroud tension shouldn’t
be too tight to allow full rotation of the mast downwind.
Downhaul System
The stock downhaul system [8 to 1] is adequate for the stronger
crews. The leach of the main will open up readily with the
application of downhaul. Because it works so well it becomes the
sole method of controlling the main on wind gusts.
In Conclusion
The 6.0 NA is a high tech around the
buoys racer that must be properly tuned to be competitive (with
other NA’s). I believe we have only begun to tap the speed
potential of this great new boat. If you have any questions or
comments please feel free to contact Mark Biggers 517-692-9430
[evenings] Note: Performance Catamaran, Inc has ask us to
condense the original tuning guide to this abbreviated form.
Names & serial
numbers of the boats are bring forward to P.C to update their
class
mailing list.
Mast Setup for the Big Guys
Spreaders should be set to 11/2” of rake. tighten outer
diamonds for 11/4” of pre-bend. tighten inter-diamond wire
just short of inducing anymore pre-bend.Note: under no
circumstance let pre-bend to go under 1”
Please note; Final measurement of the pre-bend, should be made
with mast lying on its side!
mast rake— (most accurate) level beams fore-aft, hang a
weight from the main halyard weight should hit the tramp appx. 15
to 18” aft of the inside ( tramp side ) of main beam.
Do not over-rotate mast down wind in heavy air!
Carbon mast, so far this seem to be
what works. The tube has all the same fittings in the same place
as the aluminum section. Follow the same guide lines.
Update Carbon spreader rake to 2.75”
with prebend approaching 2.0” with inter-wires loose.
Heavy Air: do’s & don’ts
Don’t over-tighten shrouds.. adds to mast compression
DO release jib in a puff before dumping main
Don’t remove spreader rake!
Don’t over-rotate mast.
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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.