Tuning Up: Macy on Rig and Trim Settings
reprinted from the Pre Season 1995 Tank Talk
Tuning the 505 rig has always been a mystery to me. Ten years ago or so
we had great speed in the breeze with an Epsilon (stiff mast, short
spreader) and a main that was three inches too short on the luff.
Five or six years ago we had some speed in fifteen to eighteen knots with
a Stratos (stiff sideways; bendy fore and aft; short spreader). Now we
have some speed in eight to fifteen knots with a D (bendy sideways; long
spreader). At almost all times in between, it seems, we didn't have any speed
in any condition. Every time I begin to understand a mainsail/mast
combination in one condition I learn about another variable that I either
never thought about or had just forgotten. I quickly realized that, for
me at least, the 505 is one large imponderable.
Why, for example, can the same North jib work equally well on a bag or a
launcher boat? Why does there seem to be no appreciable difference between
a long and short luff jib? Why do you depower a Stratos with just rake
when it appears that you should depower a D with rake and bend? Why did
Taylor/Penfield, Bixby/Lewis and Knapp/Lewis win World Championships in
relatively heavy air regattas sheeting inboard and now we think you must
sheet outboard in the breeze? Does a boat spin around a gybing board or
does the board rotate 2.2 degrees within the hull? Does it matter that
the wall thickness in some Ds vary sufficiently so you need spreaders of
unequal length to make the mast stand up straight? I simply don't know. I
can only think that there are more variables than most of us can see and master.
I have spent ten years trying to achieve good speed in moderate conditions
on the theory that most races are sailed in those conditions. Here is our basic
set up in moderate conditions for Ethan Bixby sails on a D in a launcher
Rake: 25 feet, eight inches
Tension: about 400 pounds
Mast bend: about 2 inches (measured by eye from gooseneck to hounds)
Main leech tension: tell tale stalled approximately 40% of the time.
Jib leech tension: tell tale stalled approximately 40% of time.
Jib sheet position: 11.5 inches from the intersection of the tank and the
floor of a Tuttle to the bearing point of the sheave; 86.5 inches from the
aft edge of the transom bar to the bearing point of the sheave.
Spreader height: 3150 mm above the deck.
Spreader angle: about 4.5 inches from aft edge of mast.
Spreader length: 17 inches from wall of mast to bearing point at outboard end of
Headstay: 4750 mm above deck.
Hounds: 4990 mm above deck.
On the water we primarily adjust rake and tension to keep the boat balanced.
Some of our competitors have suggested that we should start adjusting the
mast bend more often.
I started using my current rig in 1990 and by the time we sailed in Santa Cruz
in 1992 had adequate, but not good, speed in the breeze. We typically
depowered by raking first (and dropping the mast ram to maintain relatively
constant mast bend). The following numbers approximate the settings we have
used as we depowered:
25'8" 400 lb.
Unlike Howard Hamlin we usually move the jib leads aft about two inches. Although
we have not raced in any velocity since the Santa Cruz Worlds, I am beginning
to think that we have been sailing with a mast that is straighter than most
of our competitors. Several of our knowledgeable competitors with virtually
identical rigs mentioned that they could always tell our rig from a distance
because we had no mast bend. That fact is interesting when one considers
that we are among the quickest in the moderate air and are struggling to
stay with the leaders in the breeze. Perhaps the others are too bendy in the
moderate air and we're too straight in the breeze.
The author, Macy Nelson, is a three time 505 North American Champion, most
recently winning in '93 and '94.