Plumb Bobbing is Plumb Crazy ... Mostly
by Geoff Mangum
Geoff Mangum's PuttingZone Instruction
Plumb bobbing only "works" (in a fashion) if you aim the hanging puttershaft down your impression of the startline, so it only confirms what you already sense, and doesn't make you a better reader of the break or make your sensing of the startline any sharper.
No one seems to recall exactly when golfers started "plumb bobbing" their putts. Employed to "read the break" of a putt, the technique is poorly understood, improperly performed, ineffective, misused, and misleading ... except when employed within its very narrow limits as a reference guide to the true vertical. Still, many golfers swear by it. Even though I think they are crazy to rely on plumb bobbing, there must be something helpful about it that is not fully appreciated. So, what is it?
What's Wrong with the Accepted Technique.
The way plumb bobbing is taught and used makes no sense at all. Common sense and geometry simply refute the technique. The accepted method is to stand some vague distance behind the ball, face the "line of the putt," suspend the putter out in front of your face so the shaft hangs vertically to gravity (usually have to point the toe down the line towards the hole or else the shaft hangs askew), use only your dominant eye, visually align the bottom of the putter shaft with your ball, and then "read" the break from whether the hole appears to the left or right of the upper section of the shaft. But the devil's in the details. Once you start asking specific hard questions about precisely how plumb bobbing should work and be performed, you get goo.
Does plumb bobbing reveal "break" or merely "slope"? These two are entirely separate perceptions. Break depends only partially on slope, and also depends upon grain, uphill-downhill tilt, grass type and height, moisture of the green, green maintenance practices, and other factors. And "break" is not quite the same as the shape of the total putt path, either, which depends on all these factors and the CHANGES in slope or contour along the way. At its best, plumb bobbing indicates "slope," and little else.
Why doesn't the shaft align with both the ball and the hole, regardless of the slope? Well, the short answer is that it does! Every single time. It's not possible to construct a scenario of ball, green contour, and hole in which one cannot position the head and eye so that the ball and hole align along a vertically suspended putter shaft. It's just a matter of the direction you aim your dominant eye's gaze. If you actually aim the gaze along the true line from ball to hole, the shaft will always align both the ball and the hole, regardless of slope and regardless of posture.
If you don't believe this, then the next time you plumb bob a putt with obvious slope and get your standard hole-to-the-side alignment, glide your head laterally a bit behind the shaft until the ball and hole are perfectly aligned. Where'd the break go? The shaft is vertical, your head and eye position relative to the shaft are the same, but the plumb bobbing's "apparent" slope has disappeared. The only difference is the direction of your gaze. In other words, if your body-head-eye axis is vertical to gravity, sighting along a shaft that is also vertical to gravity ALWAYS aligns the ball and hole UNLESS YOUR DIRECTION OF GAZE IS OFF TO START WITH.
If you drew a chalk line between the ball and hole, this "no break" look perfectly aligns the shaft with the chalk line all the way to the hole. This means the usual plumb bobbing technique DEPENDS on sighting along some line other than a straight line from the ball to the hole in order to see any so-called "break" at all.
How do you set the original gaze or line of sight that produces the "apparent" slope in plumb bobbing? In a word, thoughtlessly. To me, the term "thoughtlessly" is bi-valent in golf -- sometimes good, sometimes bad. If you really want to look straight along a straight line between the ball and hole, you suspend the putter shaft and then adjust your stance and gaze until the ball and hole align. What appears to be going on instead in plumb bobbing is that golfers are pointing their gaze along their IMPRESSION of the putt's startline, given a general holistic understanding of the slope, break, and total putt path implied. The impression is gained subconsciously, without thought or (much if any) analysis. That's the good news, since such impressions are often not bad at all and shouldn't be formulated with analysis anyway. The bad news is practically no golfers appreciate the role of this impression in biasing the technique of plumb bobbing, so plumb bobbing can actually lead you away from the fairly good impression into something dumb and supplant other more accurate reading techniques.
This is one of the reasons why no one tries to plumb bob putts with gigantic breaks -- unless this tentative startline impression is fairly close to a straight ball-to-hole line, plumb bobbing shows its silliness openly. This is also the reason why some gurus, more careful than others, caution that plumb bobbing cannot be used for more than a "general" indication of break direction, and should not be relied upon for the precise extent of break. So, the better your prejudged "impression" of the slope and break to begin with, the better the plumb bobbing will serve as an indicator. Hence, this sort of prejudged plumb bobbing simply confirms your impression of the break because it could not possibly do anything else.
If break depends on speed, how can plumb bobbing indicate break? For the reasons above, plumb bobbing doesn't indicate the extent of break, ever. There is no way to use plumb bobbing, for example, to see the maximum break with the slowest speed or the minimum break with the fastest speed. And of course, plumb bobbing has nothing to do with uphill-dowhill issues or with grain and other conditions affecting break and the total putt path.
How does your posture affect plumb bobbing? The usual lore teaches the golfer to "stand" behind the ball but those who carefully analyze plumb bobbing state that you need to stand "orthogonal" to the surface beneath your feet, rather than upright to gravity and the center of the earth. Almost everyone, though, ignores this and instinctively adjusts the posture so that the head and body are "upright" with respect to gravity, not the slope. Intuitively, this is similar to a surveyor "setting" his instrument to vertical with bubble levels at the base of the scope.
But careful analyst say this is wrong -- you should stand with the tilt of the surface. With this body and head orientation -- if there is any slope -- a tilted head looking across a putter shaft that hangs vertical to the earth, with the bottom aligned with the ball, is supposed to reveal the slope-created discrepancy and show the hole "apparently" off to the side of the shaft.
Does it? No, it doesn't. Even if your posture is tilted, so long as your gaze is directed down the baseline to the hole, you're only using one eye to sight, so the putter shaft will STILL align the ball and hole without indicating slope. The tilting of the eye doesn't affect the direction of gaze -- tilt only rotates the eyeball without affecting the direction of gaze. The tilt does shift the eyeball laterally, but once you realign the shaft on the ball, with the same gaze direction, you still see the ball and hole align, revealing nothing about slope.
To get anything that seems to work at all, you have to stand upright to begin with and align the gaze straight at the hole, setting the ball and hole on the shaft, and THEN change your posture to tilt with the surface. The gaze now sees the hole to the side of the upper shaft because the tilt shifted the gaze off to the side of the shaft.
There are more problems, though -- no one ever does it this way to begin with and in any event it is very difficult to orient the head and body to a surface rather than to gravity because eveything useful opposes this. The biggest problem, however, is that so-called "correct" plumb bobbing indicates slope, allright, but the only slope it actually indicates is the slope beneath your feet -- not the slope AT the hole and not the slope BETWEEN the ball and hole. The slope beneath your feet is essentially insignificant as it does not affect the breaking of the ball during it's roll to the hole. For this reason, some experts suggest that plumb bobbing has to be done from several points between the ball and hole in order to get a true "read" of the contour -- and no one wants to get into that!
Even so, in many cases, the slope between the ball and the hole is pretty much the same. In this one case, plump bobbing can be useful -- when you correctly orient the line of sighting with the dominant eye along the baseline, when you adjust your posture properly to shift your gaze, and when you are careful to check that the slope is pretty much the same from ball to hole. In this case, you get a fairly convincing confirmation of your subconscious read of the slope. Then you still have to factor in grain, uphill-downhill, and other factors affecting actual putt speed and break. But why go to all this trouble, since you have to know the slope to shift your posture accurately to begin with?
What about plumb bobbing while squatting, or standing off the green? This is really nuts. Off the green, plumb bobbing gives you zip for reliable information about the contour the ball must roll over. Squatting, it is much more difficult to orient the head and eyes to the contour beneath your feet, and you end up with the head and eyes vertical to gravity.
What Plumb Bobbing is Good For.
So, what if anything is useful and accurate from plumb bobbing? Plumb bobbing strikes people as effective because it confirms the subconscious read of slope (not break), which depends upon posture and sighting-alignment biases, and because in these cases it seems seldom to hurt the putt. The ball almost always breaks in the direction one expects. In any case, putts that are off the mark are much more readily blamed upon some misjudgment or misexecution in speed, the stroke, or the setup rather than in the technique of plumb bobbing. After all, anyone who uses plumb bobbing assumes they are doing it correctly -- otherwise they wouldn't try it at all.
As plumb bobbing is actually used, with upright posture and biased sighting alignment, the technique nonetheless provides a reference of true vertical. The brain is doubtless thankful for small favors. The visual system and the balance system in effect get calibrated by the true vertical shaft. The golfer is then more accurately able to assess slope and break just using his eyes, feet, and sense of balance -- so this limited sort of plumb bobbing helps here.
And if you want to know where the baseline runs along a straight line from the ball to the hole, plumb bobbing helps, but it is just as well to use the shaft as a "ruler" in visually aligning the two targets (ball and hole). This sense of the actual location of the baseline can then be used in judging the SHAPE and LOCATION of the breaking path of the putt all along its route, as this the total putt combines the read of slope and contour with the envisioned speed or energy pattern of the putt. And this is what you really need to get down to.
Make This Part of Your Game.
For plumb bobbing to be useful and reasonably accurate, you have to know the slope you're standing on with some fair degree of accuracy. Rely on your sense of balance, vision of the general scene, and feet to get this right. Even then, all you get is a general indication of the slope. And don't forget uphill-downhill, grain, wetness, and other conditions affecting "break" and the ultimate shape and location of the putt path. The dangers of taking plumb bobbing too seriously as an accurate indicator of slope considerably outweigh the gains you get in apprehending the slope, break, and the optimal path for the putt more dirrectly. Use plumb bobbing whenever you want to get a reference for true vertical -- it helps quite a bit. But forget plumb bobbing to "read the break." It's plumb crazy.
© 2001 Geoff Mangum. All rights reserved. Reproduction for non-commercial purposes in unaltered form, with accompanying source credit and URL, is expressly granted. For more tips and information on putting, including a free 10,000+ database of putting lore and the Web's only newsletter on putting (also free), visit Geoff's website at http://www.puttingzone.com, or email him directly at email@example.com.