Bird,
The options are:
Zimmerer's charts are way off./w3tcompact/icons/frown.gif
Your mower is really only has a 4 ft blade./w3tcompact/icons/frown.gif
Your speedometer(?)is fast. /w3tcompact/icons/smile.gif
You have more land than you thought. /w3tcompact/icons/smile.gif
You are mowing your neighbors yard, too. /w3tcompact/icons/smile.gif
It is a long way from the barn to the mowed area. /w3tcompact/icons/smile.gif
You are taking long breaks when your wife thinks you are working. /w3tcompact/icons/smile.gif
Seriously, I have just used their data to get in the ballpark. They have a lot of errors in the data, but you can usually figure it out.
If you figure you get a 4 ft cut with a 5 ft mower then 55 trips per acre and 220 ft per cut is 12,100 feet or 2.29 miles traveled per acre or 2 acres/hour at 4.6 mph. I suspect he doesn't allow as much overlap as we do.
Got a lot of rain this weekend. About 3 inches of it came down in a deluge and washed away about $200 of roadbase on the driveway. Also have a little coastal growning through the perimeter fence. /w3tcompact/icons/smile.gif Glad to see 4.5 inches of rain. That should hold things for about 3 weeks! /w3tcompact/icons/smile.gif