An additional acronym: MOI
Golf acronyms are getting out of control.
For years the only abbreviations you needed to know were USGA, R&A and GIR. But with thin-faced drivers came COR (coefficient of restitution). And just as folks were getting comfy with that one, another came along -- MOI or moment of inertia.
Simply put, moment of inertia is the term used to describe a clubhead's resistance to twisting when the ball is struck. For example, your swing is a little off and you hit the ball on the toe of the clubhead or you strike a putt off-center. A clubhead with a higher MOI will twist less, reducing the effect on the shot.
Like COR, the MOI of a club can be expressed as a numerical measurement. And although the MOI number normally is not found on clubs, some companies, such as MacGregor with its Bobby Grace MOI putters, are stamping clubs with the measurement. In addition, others, such as Ping with its Doc 17, now tout a "high MOI" benefit.
Ralph Maltby, a club designer for The Golfworks, conducted several tests that showed that changes in the moment of inertia had a substantial impact on the overall playability of a club. Maltby believed so strongly in the premise he invented the Maltby Playability Factor -- a system that rates a club's forgiveness based on its moment of inertia.
"The tests proved conclusively that moment of inertia was the design element with the most impact," said Maltby. And although some club designers may dispute that claim, few would challenge the importance of MOI, particularly on putters.
| In The Winner's Bag |
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Vijay Singh Ball: Titleist Pro V1x Driver: TaylorMade R510, 10.5 degrees 3-wood: Cleveland Launcher, 13 degrees 9-wood: Callaway Steelhead Irons (3-9): Cleveland TA1 Form Forged; (PW): Cleveland 588 Gunmetal Wedges: Cleveland 900 Gunmetal (54, 60 degrees) Putter: MacGregor Bobby Grace MOI Hale Irwin Ball: Titleist Pro V1 Driver: TaylorMade R500, 8.5 degrees 3-wood: TaylorMade 200 Tour, 13 degrees 4-wood: TaylorMade 200 Tour, 17 degrees Irons (2-PW): TaylorMade rac LT Wedges: TaylorMade rac (56 degrees) Putter: TaylorMade Rossa Modina |
According to conventional wisdom, putts struck off-center result in the putterhead twisting, thus imparting a sideways roll and consuming energy that otherwise would be transferred to the ball. The result: short, off-line putts. This was especially true of blades such as the original Bulls Eye or Cash-In putters. Now, like game-improvement irons before them, many putters boast weight in the heel and toe, resulting in a higher MOI and greater stability at impact. In short, a putter with a high MOI should help your putting -- and that's an abbreviation everyone can appreciate.
Equipment scoop from the tours:
The number of putter brands used by the 156 PGA Tour players at last week's Shell Houston Open. Titleist's Scotty Cameron line was the top brand with 68 putters in play. The next seven brands combined had 69.
E. Michael Johnson is the Equipment Editor of Golf World magazine
