1. Alan M. Nathan University of Illinois a-nathan@uiuc.edu
Bat Performance and the NCAA Certification Protocol Does Aluminum Outperform Wood? Presentation made to the ASTM Subcommittee on Bats and Balls May 23, 2007
Alan M. Nathan
University of Illinois

2. REMINDER: Three parameters determine batted ball speed (BBS) in the field
BBS = (BESR-0.5)vpitch+(BESR+0.5)vbat
measure BESR in the lab
define “standard field conditions”
--vpitch
--vbat (depends on MOI)
use these to predict BBS in the field

3. Relation between swing speed and MOI
aluminum
wood

4. The NCAA Bat Certification Process
Each bat is characterized by two regulated numbers:
BESR: performance metric for fixed bat speed
MOI: metric related to field bat speed
Together, these determine BBS
Higher BESR, higher MOI
 same BBS
higher BBS
MOI
BESR
same BBS
Same BESR, lower MOI
 Higher BBS
lower BBS
Same MOI, lower BESR
 Lower BBS

5. Example: 34” Bats
102 mph
MOI limit
max vf
BESR limit
97 mph
typical wood
All bats below horizontal line and to right of vertical line are allowed

6. Conclusion
The NCAA certification protocol limits field performance of non-wood bats
Under “standard” conditions---
Wood = 97 mph
Non-wood < 102 mph
Difference < 5 mph, or about 5%

7. Does aluminum outperform wood?
Summary: The NCAA certification protocol limits field performance of non-wood bats
Does aluminum outperform wood?
YES, by about 5%
the 5% is an estimate based on the current state of the science
left unregulated, aluminum would outperform wood by a significantly greater margin