Dear Frank:
With The Masters coming up this week I was wondering about green speed and how this is determined for this championship. The greens are always so slick and scary looking!! I read that you were involved with the Stimpmeter and thought that maybe you could answer my question.
Thank you,
Marge
Marge,
Yes, I was involved with the Stimpmeter. In 1976 I re-designed a device that had been developed in 1935 by Eddie Stimpson but rejected by the USGA at that time. The original was not very consistent in its readings. I first tried out two very elaborate designs of my own, which turned out to be good but clumsy, and dependent on the skill of the operator. I then took Eddie’s concept and redesigned it, and since the conception was his I called it the Stimpmeter, which was what he had called his.
A ball is positioned in a slot at the top end of a ‘V'- grooved aluminum beam. The beam is slowly raised until gravity pulls the ball out of the slot and it runs down the groove onto the green. The distance it rolls from the end of the Stimpmeter on a flat portion of the green is the speed of the green, measured in feet. It is very consistent, simple, and now used around the world.
In 1977, I asked our agronomists at the USGA to measure greens during their visits to various clubs. They returned data that I analyzed to try to develop some standards for green speeds. This proved to be 66 for everyday play at golf courses, and 8' 6'’ for average competition play. For championship play in 1977, 10' 6' was considered fast. To reach that speed, we had to double or even triple cut the greens; we made sure that if the greens were undulating we would keep the speed somewhat slower.
In 1998, at the Olympic Club in San Francisco during the US Open the fairways were running at 6' 6'. Not only had significant agronomic changes taken place, but mowers designed for greens were being used on the fairways. Today, if you want to roll the greens and really shave them down, you can get them as fast as 15 feet, as was the case at Bethpage Black on the Sunday of the Open in 2002.
The green speed at Augusta National is a secret, but whatever it is it should be fair and very much dependent on the undulations of the green. You never want to have the ball accelerating past the hole from any direction; if it does, then either the hole location is inappropriate or the speed is too fast. A ball should be able to stop close to the hole when putted from almost any location on the green. This does not mean it should be easy to do, but it should be possible. With the above in mind, there is quite a responsibility on the shoulders of the individual in charge of dictating green speed and hole locations. I suspect the greens for the Masters will be close to 12 feet.
For more on the Stimpmeter please click here.
Hope this helps,
Frank
Frank,
Thank you for sharing your experience in a weekly column. I look forward to reading it every week.
I have a question regarding moment of inertia and I haven’t been able to find the answer. What, if any, effect does the length of the club and the loft of the club head have on MOI?
Thanks, Frank,
Bobby
Bobby,
The MOI (Moment of Inertia) is a measure of the resistance to angular acceleration -- in other words, twisting. (Click here for an easy explanation of MOI).
You can experience this by holding two weights (20 lbs) close to your body, one in each hand, and twist your torso quickly through about 180 degrees. Now stretch your arms out and try to twist again. This time it will be more difficult to twist quickly, and, once you get started twisting it will be more difficult to slow down. What you have done by moving the weights away from your body (the axis of rotation), is to increase the MOI.
This is why cavity back clubs have a higher MOI than blades and are more forgiving of mis-hits -- because they dont twist as easily. The weight has been moved to the outside perimeter of the head. Similarly, in hollow metal wood clubs, all the weight is distributed into the shell, so they also have a high MOI. The result is that the club head doesnt twist easily on off-center impacts, and so imperfect shots fly straighter.
Only now can I answer your specific question. If you are talking about the MOI of the head itself, then changing the length of the club or the loft will have no effect on the MOI of the head.
You should, however, also understand that the measurement of MOI is based on the axis of rotation, which in the case of the club head alone is its center of gravity. If we try to measure the MOI of the club as a whole -- the shaft, grip and head -- and the axis of rotation is at the grip end, then the length of the club makes a big difference.
Try to hold a club at the head end and swing the grip. Now reverse this and hold it at the grip end and swing the head. It will be much easier to swing the grip than to swing the head. This is because the head is heavier than the grip and at some distance away from the axis of rotation (your hands). The MOI is different. Thus, by changing the length of the club you are also changing the MOI of the club as a whole -- but not changing the MOI of the head itself.
I hope this helps you better understand MOI, which every body talks about but now you understand.
Frank
Frank:
Your following comment really got my attention:
DON’T add weight to the butt end of the club to achieve a certain swingweight. This is done sometimes in club fitting to make the customer happy, but it does absolutely nothing for you.
I have been reading a lot about MOI fitting, and each article seems to indicate adding weight to the butt is the magic fix. Grip manufacturers are even selling grips with a special feature for adding weight. Whats the real story on MOI fitting?
--Gerald
Gerald,
Matching by MOI of the club is normally done by making a measurement about a specific axis somewhere close to the grip end of the club. If this is based on the last foot or so before impact, the point would be about 4 inches above the grip end, as this is the instant center of rotation in this segment of the swing.
Adding weight to the grip to change the MOI of a club is not very effective. This should be done by changing the weight of the head or lengthening the club.
Adding weight to the grip end is the equivalent of wearing a heavier glove or even a wrist watch. This does change the MOI of the first lever -- i.e. the arms, with the attached hands -- but does nothing for the MOI of the club if we are placing the axis of rotation in the vicinity of the hands.
If adding weight to the grip really worked wonders, dont you think after 400 years of trial and error we would have discovered this before now?
My position is, if it feels good, try it. Adding weight to the grip end will certainly increase the hand mass and the MOI of the first lever. But since the club head path changes its radius of rotation throughout the downswing, I dont know the value of this particular form of balancing for MOI, since it is wholly dependent upon what axis of rotation you are using as a basis for measurement.
In general, I do not see how butt weighting can be the magic fix, or how it is going to have a significant effect on performance.
Frank
Frank Thomas, inventor of the graphite shaft, is founder of Frankly Golf, a company dedicated to Helping Golfers. Frank is Chief Technical Advisor to The Golf Channel and Golf Digest. He served as Technical Director of the USGA for 26 years and directed the development of the GHIN System and introduced the Stimpmeter to the world of golf. To email a question for possible use in an upcoming Let’s Be Frank column, please email letsbefrank@franklygolf.com
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