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See the Line Every Time! The EOB Putting System

Using the Putter to Plumb Bob a Green: theory, practice, and limitations

Dear Dr. Putt:
Is there anywhere I can find information, pictures, tutotials or advice on plum bobbing? I have seen many golfers use this technique and I have never had anyone really explain the technique. Could you please lead me in the right direction.

My Dear Larry:
With all due modesty, you have already come in the right direction, for Dr. Putt has had a number of questions recently on this issue. And given that Dr. Putt in one of his earlier reincarnations taught geometry, he is most prepared to address this issue. In fact, there are several related issues: how it works in theory, sources of error, and cost/benefit analysis in actual application.

First things first. In yet another reincarnation, Dr. Putt was a college professor, so he would be remiss not to point out that the term "plum" is properly spelled "plumb." Literally it means vertical. This gets to a necessary preliminary issue, how one can establish a vertical line with use of the putter. Few putters will be perfectly vertical in three dimensions unless they are perfectly balanced. However, one can establish a vertical line in two dimensions. (One really does not need the third dimension since one will be sighting from only one direction relative to the putter.) What one should do is hold the club with two fingers just below the grip and sight it to the edge of a door or some other opening that is perfectly vertical. Slowly rotate the putter until the shaft appears to be perfectly parallel to the known vertical edge. Then mark the top of the grip so that one can consistently hold the putter in this position when plumb bobbing quickly and accurately on the putting green. If the player fails to do this properly, then all the rest is an exercise in futility.

Now that we have established an instrument to measure a vertical or "plumb" line, of what use can it be in determining the coutour of the green? Here is where most players, including many professionals, become lost. In an article in a national golf publication a few years ago, some well-know tour players said that they did not understand how the technique worked. So you have some quite respectable company sharing your confusion.

The key to understanding the theory behind plumb bobbing to compare what one sees when the green is level with what one sees when the green is tilted up or down from left to right. To help us visualize what transpires, Dr. Putt has enlisted the aid of Mr. S.L. Green, known to his playing chums as "Slim" Green.

Let us look first at Slim standing and using the plum bobbing technique on a perfectly level green. (See the figure below. In this case the green is white so that Mr. Green and what he sees stands out for your viewing pleasure.) You will note that Slim stands with his dominant viewing eye over (or plumb with) the line that extends from the hole through the ball. The putter shaft is also plumb with that line. From his point of view, everything lines up. The shaft splits the ball and the center of the hole, telling him that the countour of this green (at least where he is standing--one of many problems that we will get to later) will create no break in the putt.

Now let us tilt the green so that the right side is higher than the left side, thereby creating a right to left break. (See the figure below.) Slim again stands on the line extending from the hole through the ball. Ideally, he would stand perfectly perpendicular to the surface of the green along a line that is perpendicular to the extended line between the ball and hole, as opposed to plumb. We will come back to that point--a major problem. But for now, let us assume that he can naturally remain perpendicular to the putting surface. This moves his head and the plumbed putter shaft to the left of an imaginary plumbed line from where he is standing. When Slim moves the putter back to the right (note how he has bent his arm to do this) so that the ball now lines up with the lower part of the shaft, the hole will appear to be to the left of the upper part of the shaft. This tells Slim that the putt breaks to the left.

This would work wonderfully if Slim could stand perpendicular to the putting surface. But he cannot without losing his balance. If he stands perfectly plumb with the line (see the figure below), then everything lines up again, and he cannot tell if any break exists.

In reality, Slim will probably stand somewhere between plumb and vertical to the surface. To the extent that he is able to stand vertical to the surface, he will have to move the putter to his right to line it up with the ball and then the upper shaft will again be to the right of the hole, though not as much as in the ideal situation (see the figure below). To better accomplish this, Slim should stand with his feet about shoulder width apart, not in the unnatural position with one in front of the other as he is doing in the figure.

In theory, one can use the technique to ascertain whether a putt is uphill or downhill by standing on a line that is at a right angle to the putting line. Using a blade of grass or some other distinctive object as an imaginary ball, one could then employ the technique. If one is standing to the right of the hole, then if the shaft lines up to the right of the hole, it is an uphill putt. To the left is a downhill putt. Few players ever extend the technique this way.

The reader will note that this procedure is frought with error. To the extent that Slim stands more in balance rather than perpendicular, he sees less break. To the extent that Slim does not stand on the extended line from the hole through the ball, he will see more or less break. Moving up the hill will subtract from the effect that standing perpendicular has on moving the point of view to the left and create the visual impression of less break. Standing off the line on the down hill side will add to the effect and create the visual impression of more break. Moreover, even if one gets all this right, the visual impression of break is created by slope where one is standing, NOT where the hole is. (However, one can get a reading closer to the hole by standing behind the hole and using the technique from the hole back to the ball.)

With all of this error, is it any wonder that few professionals employ the technique. Moreover, it takes a lot of time, and most of us already spend too much time in looking at putts. One would be better advised to watch closely as others putt and to watch closely how chips break as they approach or pass the hole. Observing these things also accounts for the effects of grain, which can have an equal or even greater effect than a subtle change in left or right slope. Incidentally, most of us fail to observe this because we are preoccupied with the fact that we missed the chip or putt. Dr. Putt would guess that the few professionals who do employ the technique do it as a confidence booster to try and reinforce what they probably already saw by careful visual examination of the putting surface relative to the surrounding ground.

The bottom line, dear reader, is that while one might have some fun experimenting with this technique in playing by oneself or in practice on the putting green, time expended far outweighs any benefits gained. Spend your time and your playing partners' collective patience on other less error-prone green reading techniques.

Dr. Putt

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Plumb Bob putting technique