Hydro - turbine, how is my math?

How is my Math? Did I get the right answer?

http://www.oksolar.com/pdfiles/Catalog-Hydro.pdf :
in watts
dynamic head, amt. flow, efficiency
(head in feet)(gallons per minute)(.18)(efficiency)
efficiency = .35 to .70

ex: (1')(1)(.18)(.40) = .072
ex 2: (2)(n)(.18)(.4) = 6000
n = (6000)(1/2)(1/.072) = (3000)(1/.072) = (3000)*(1000)/72 = 41666
ex 3: (5)(10)(.18)(.6) = 5.4
ex 4: (10)(1000)(.18)(.6) = 1080
ex 5: (100)(100)(.18)(.6) = 1080
ex 6: (20)(100)(.18)(.6) = ( 20)(100)(.108) = 216
ex 7: (10)(10)(.108) = 108
ex 8: (2)(10)(.108) = 2.16
ex 9: (5)(10)(.108) = 54
ex 10: (5)(5)(.108) = 27
ex 11: (5)(1)(.108) = .54
ex 12: (10)(1)(.108) = .108

For a 10 hour period
#6 = (216)(60)(10) = 129600
#7: (108)(60)(10) = 64800
#8: 1296

1000 gallons / minute = 16.667 gallons / second
100 gallons / minute = 1.667 gallons / second
10 gallons / minute = .1667 gallons / second