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Virginia golfer | September/OctOber 2013
Master_VSGA_Sept13_MASTER2.indd 32
grooves for conformance to
the stipulations governing
groove angles, spacing, depth
and volume.
Ball Approval: The minimum
diameter of a golf ball must be 1.68
inches. There is no maximum. So
could a manufacturer make a ball, say,
two and a half inches in diameter?
“Sure,” Spitzer says. “But I wouldn’t
make one more than four and a half inches
wide. It wouldn’t fit in the hole.”
On arrival at the lab, submitted balls are
cooled to 23 degrees Celsius (75 degrees
Fahrenheit). This assures that difference in
heat will not affect launch speed, trajectory
or distance during the testing. They are
labeled and inspected to ensure symmetry
(the Titleist Pro V1 had a bit of an issue
with this originally). At the indoor test range,
the USGA measures distance trajectory and
roll via a 70-yard-long tunnel lined with
15 sensors. Balls—some 20,000 per year
from roughly 1,000 submissions—are hit by
a mechanical robot swinging at 112 mph,
deemed the average swing speed for a
professional golfer.
STIMP SOLUTION
The USGA makes a lot of its testing
equipment itself, mainly because,
truth be told, it doesn’t exist
A USGAelsewhere. They conceived
developed clubhead
and built their own Plinker.
size measurement tool
What looks like a heavyis used to determine
conformance to
duty bilge pump actually
maximum length and
measures ground comheight of the
pactness. This “Tru-Firm”
clubhead.
simply comprises a plunger
released down a tube, whereupon they measure how much the
plunger rebounds back up the tube. The
idea is to keep green compactness consistent
throughout a course during a championship.
In a similar vein, the USGA has developed
“Stimpmeter 2.0.” For the uninitiated, the
Stimpmeter was invented in 1935 by an
amateur golfer named Edward Stimpson to
measure the speed of greens. It comprises
a three-foot-long piece of metal with a
V-shaped groove down the middle which,
when laid on a green and then raised to
a gradient of 20 degrees, creates a slope
down which a ball is rolled. How far the
ball subsequently rolls on a putting surface
determines the speed of that particular area.
You will read of greens running at 10 or 11—
the ball rolled 10 or 11 feet.
The USGA started using it at the 1976 U.S.
w w w. v s g a . o r g
8/30/13 8:38 AM
TOP: JOHN MUMMERT/USGA PHOTO ARCHIVES (2); SPITZER: MATT RAINEY/USGA PHOTO ARCHIVES
Below are just a few of the technical items on the USGA Research
and Test Center’s agenda.
Characteristic Time: This
replaces what the geeks among us
may recall as COR or coefficient of
restitution. The goal is to prevent
a club from having so much spring
that it would hit a ball too far,
therefore removing skill and its intrinsic
challenge. Instead of gauging this by
Grooved
firing a golf ball at a golf club,
test plates are
the USGA now uses a fixed club
used to get
and a small, swinging pendulum
a gauge
with a ball-shaped lump on its end.
on spin.
How much the pendulum rebounds
determines the spring of the clubface.
Officially it’s called the “Pendulum Test.”
Invented by Pringle, the USGA staff tried
it a few times and christened it “The
Plinker.”
Clubhead Measurement: Long gone are
the days of holding a clubhead in one hand
and a ruler in the other. Now they use lasers.
Clubhead Shape: The Rules of Golf decree
that a clubhead must be “traditional
and plain” in shape, which clearly is
a subjective determination. It’s caseby-case.
Moment of Inertia: If a golf club
strikes a ball with an off-center part
of its clubface, the club will rotate
around its center of gravity (think of
pushing someone’s shoulder instead
of his or her chest). The challenge
is to avoid that, as it usually means
“fore” left or right. Manufacturers
are allowed to be forgiving, but
not to the extent that the skill and
challenge is reduced too severely.
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