Patrick,
I heard they were running 19.....
and their cups were smaller...
or maybe their balls were just bigger
Jeff,
Truth be told, on windy day's they were running at 24.
Just to show you what nonsense this is, I'm going to try to post the article about green speeds and slope, which deals with balls that won't stop.[/color]
GREEN SPEED PHYSICS
The laws of physics applied to golf course maintenance practices.
by ARTHUR R WEBER
GREEN SPEED PHYSICS
The laws of physics applied to golf course maintenance practices.
by ARTHUR R WEBER
MOST ALL putting greens are neither level nor plane,
some being more or less severely contoured and
sloped than others. Consequently, Stimpmeter
readings, taken over such dissimilar surface profiles, correlate
differently as a linear measure of green speed. That is to say,
green speed ratings, popularized as they have been by
averaging Stimpmeter measurements taken on reasonably
level greens, do not fairly and accurately serve as speed
indices common to all putting greens. Rather, by preparing
an "as built" green to Stimpmeter readings adjusted for its
inherent angularities, uniformity of speed can prevail from
green to green, stabilizing the composures of golfers and
green superintendents in the process.
By mathematically interpreting the physics fundamental to
a golf ball rolling over a putting green upon release from a
Stimpmeter, indices are derived, as angularity-consistent
measures of speed rating characteristic of "as-built" slow-tofast
greens. These indices are graphically plotted to facilitate
their use by golf course superintendents, golf committees,
tournament officials, and the like.
Modeling Golf Ball Roll
The coefficient of friction between a golf ball and the
putting green surface over which it rolls can be quantified by
using a Conservation of Energy model as the computational
basis for analysis. Stimpmeter measurements, supplemented
by green slope measurements over which the Stimpmeter
readings are made, are fundamental to the applicability of
such an analysis to all putting greens, no matter their
angularities or undulations, however severe.
When coefficient of friction values result from Stimpmeter
measurements either taken on or normalized to level greens,
the measurements range from a low of about 6 feet for what
are categorized to be slow greens to a high of about 12 feet
for fast greens. But therein lies a rub, because all greens
are not level; rather, they are architecturally contoured with
slopes, if not marginally, for drainage. Moreover, few putting
green slopes are unidirectional; most are compound contoured.
Notwithstanding, golf course putting green speeds
can be equalized and controlled, over the full range of slowto-
fast, by correlating Stimpmeter and putting green slope
readings to coefficient of friction values. Said another way,
using Stimpmeter measurements made on level greens as
numerical benchmarks to characterize slow-to-fast greens,
Stimpmeter readings can be indexed for all 18 golf course
greens, having first surveyed their angularities, to
comparatively measure up to a desired benchmark speed.
Coefficient of Friction
For the purpose of the analysis, the coefficient of friction
can be generalized to encompass, without distinction, the
static, dynamic, and rolling coefficients of friction that prevail
during the putt of a golf ball starting at rest and rolling to a
stop. It can be normalized to an all-inclusive parameter
because of its dependence on many variables. Among them,
the most influential of which would be the height of cut, are
the morphological and growing characteristics of the turfgrass
species, the turf density and uniformity, the thatch layer, the
dimpling pattern and the construction of the golf ball, the
season, the wetness, even the time of day.
Despite the influence of these variables and others, the
green speeds of "as built" undulating greens can, with
reasonable accuracy, be articulated and prepared analogous
to the benchmark green speed indices from Stimpmeter
measurements taken on level greens.
Level Putting Surfaces
The mathematical parameters and variables affecting the
energy conservation relationships, when making Stimpmeter
measurements on a reasonably level putting surface, are
depicted in Fig. 1, where:
W= weight of golf ball, 1.62 oz.
H = height of Stimpmeter notch above horizontal upon
golf ball release, in.
0 = angularity of Stimpmeter notch above horizontal
upon golf ball release, 20.5 deg.
L = Stimpmeter length, 36 in.
V,: = initial golf ball velocity across the putting surface
from the foot of the Stimpmeter, ft./sec.
V0 = final velocity of golf ball after rolling across the
putting surface to a stop, zero
S = Stimpmeter reading, ft.
f = coefficient of friction between rolling balls and the
putting surface, dimensionless
g = gravitational acceleration constant, 32.2 ft./sec.
Only S and f, as a function of S, are variable; the other
parameters, in addition to W, 0, L, and g, remain constant,
to wit:
H = Lsin0 (1)
= (36)(sin 20.5) = (36)(0.350) = 12.6 in.
and subsequently, the total Potential Energy, PE, stored in
the golf ball prior to release down the Stimpmeter is:
PE = WH (2)
= (1.62)(12.6)=20.4in.-oz.
Figure 1
.Golf Ball
L ^ Stimpmeter Putting Green
Vn
12 USGA GREEN SECTION RECORD