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All the Same CoR to Me

Nov. 27, 2007     By     Comments (2)

Just how hot is that driver in your bag?

Bag DropAnd now all is right in the world. The R&A reminded golfers on November 11, 2007 that a new rule would go into effect on January 1, 2008 that would align themselves with the USGA to have a limit to the "spring-like" effect of drivers and establish a world-wide coefficient of restitution (COR) limit of 0.83 for all drivers, down from their previous limit of 0.86.

While this ruling doesn't mean much to most golfers (especially those under the rules of the USGA) it will have an effect on the rest of the world as some previously legal drivers will now need to be replaced in order to fall under the new limit.

Physics
I could go into detail about the various types of collisions and "spring-like" effects on drivers, but I don't have a degree in physics and Ralph Maltby already has a good explanation and some examples to better understand the coefficient of restitution and what it means to distance and drivers.

Ruling Bodies
In 2002, the USGA and R&A were ready to go towards establishing a coefficient of restitution (CoR) limit for drivers. The prevailing thought was that the USGA would up their CoR limit from 0.83 to 0.86 over a five-year period beginning in 2003 ("highly skilled golfers" would be limited to 0.83). Manufacturers were ramping up efforts to get "hot" drivers out in the U.S. market in anticipation of the new ruling. The few companies that already had non-conforming drivers out on the market were getting ready to market this change. Golfers of all levels had visions of hitting longer drives dancing through their heads.

What happened? Well, the R&A never really went along with the 0.86 limit (or any number for that matter) and there was mass confusion over the non-definition (or lack thereof) of what a "highly skilled golfer" was and who could only use a driver with a CoR of 0.83. In the end, the USGA went with a CoR of 0.83 limit for where their ruling would govern and the R&A would not have a CoR limit at all. One addition mandated that a 0.83 CoR would go into effect for all golfers around the world effective on January 1, 2008.

Guess what date is right around the corner?

The R&A has established a list of conforming and non-conforming driver heads for you to peruse to ensure the driver currently in your bag will be good to go on January 1, 2008. If anything, the new ruling gives you a great excuse to go out and get a new conforming driver for the holidays.

Conclusion
In the end, what does January 1, 2008 mean to you besides sleeping off too much champagne and watching bowl games? If you've been living in the U.S., it means relatively nothing. If you follow the USGA's Rules of Golf, you should have banished your non-conforming driver to the garage or to online auction a few years ago.

The rest of the world is about to lose a meter or two on their drives, however, and there may be some increases in driver sales as golfers who may have been playing with a driver with a higher CoR will now have to replaced with a conforming one, if they follow the rules of the R&A.

One final thought on this issue. Now that an universal CoR is officially established, is this the end of the discussion or could the USGA revisit this at a later date in an attempt to "roll-back" distance? It wouldn't be the first time they've looked at rolling back the clock on golf equipment.

Discussion

  1. Slice says:

    :grin: I already have a conforming club, but the wife doesn't know...look who's getting a new Titleist this December!

  2. Omar Rocha says:

    They should go a lot lower with this one, anyway its a good step forward.

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