Acres cut per hour

[Builder]

Anyone ever see a chart that combines ground speed with deck width to calculate how much acreage can be cut in an hour?
Got a finish mowing contract-about 20 acres. I usually do larger rough areas with bush hog. Would like to calculate time it will take to cut. Have to buy a flail or finish mower for the job. Would like to see what width & speed would be needed to finish it in 8 hours.

 

[Farmwithjunk]

Width of cut (as opposed to width of mower)in inches X mph divided by 100 = acres per hour (at maximum efficiency)

Deduct for time spent turning, mowing around obstructions, ect...

"Width of cut" has to reflect overlap to be anything like accurate...

This is a quick, easy way to get a close estimate.

 

[Will_C]

I remember seeing a chart like that on a website...either Scag or Exmark, or perhaps both.

Will

 

[jenkinsph]

Farmwithjunk,
That works out to be very accurate, certainly close enough to make me remember it. Thanks for the heads up.:thumbsup:

 

[Builder]

Thanks FWJ. Anyone think 4MPH is a reasonable speed mowing 12-18" tall pasture grass with a 8' finish mower behind my M-7040?

I usually only do bush hogging. When I bush hog, I go ~3MPH with an 8' bush hog through 5' tall weeds, but it leaves some sticking up here & there.

According to my calculations. I should be able to cut 3.8 acres/hour at 4MPH w/ 8' finish mower. I would reduce that to 3 acres per hour to account for turns. So I should be able to mow 20 acres of light pasture in under 8 hours with a 8' finish mower if I run at 4MPH.

Sound plauseable?
I pretty much got the mowing contract, now I gotta find a big finish mower. Flail or finish is the next step.

 

[dkjbama]

TractorData.com - Mowing with tractors
It doesn't output in acres/hr, but I've found the mowing-time calculator at this link to be useful. The HP/width graph is informative as well.

 

[Verticaltrx]

Here's another formula that I use:

(Width of cut in feet x MPH x % efficiency)/8.25

The % efficiency in this equation reflects overlap, time for turns, etc. 100% efficiency would be like mowing full width no turning, stopping, etc.

For example:

(8' x 4mph x .75)/8.25 = 2.91 ac/hr

 

[jenkinsph]

Thanks FWJ. Anyone think 4MPH is a reasonable speed mowing 12-18" tall pasture grass with a 8' finish mower behind my M-7040?

I usually only do bush hogging. When I bush hog, I go ~3MPH with an 8' bush hog through 5' tall weeds, but it leaves some sticking up here & there.

According to my calculations. I should be able to cut 3.8 acres/hour at 4MPH w/ 8' finish mower. I would reduce that to 3 acres per hour to account for turns. So I should be able to mow 20 acres of light pasture in under 8 hours with a 8' finish mower if I run at 4MPH.

Sound plauseable?
I pretty much got the mowing contract, now I gotta find a big finish mower. Flail or finish is the next step.

Reminds me of docking a boat, "Never approach the dock faster than you are willing to hit it."

I might consider going a little slower if the ground is hard to see the first cut. I am sure you can easily choose the right speed within a short time in the seat, just make sure you STAY in the seat.

 

[Builder]

Steve,

Ground is easily seen, so all is well there. I just bush hogged on Tuesday. Did about 40 acres and I'm pretty sure I was running about 2.9MPH. I'm pretty sure I could mow in 4th gear low range.
Seat belt will be buckled! :thumbsup:

 

[kco]

Here's another formula that I use:

(Width of cut in feet x MPH x % efficiency)/8.25

The % efficiency in this equation reflects overlap, time for turns, etc. 100% efficiency would be like mowing full width no turning, stopping, etc.

For example:

(8' x 4mph x .75)/8.25 = 2.91 ac/hr

That's the EXACT formula. Gotta love the English measurement system. :confused2: An acre is 1 rod (16.5 feet) by 1/2 mile or 1/2 rod (8.25 feet) by 1 mile or 43,560 sq. ft. And of course there are four rods in a chain (66') which are the width of prairie road allowances (except they are 1.5 chains in some places).

The money system used to be as much fun. I visited the UK in 1965/66 when the common coins were 1/4 pence (farthing), 1/2 pence, 1 pence, 6 pence, 1 shilling, 1/2 crown (2 shillings, 6 pence), 1 crown (five shillings), and the pound.

There were 12 pence per shilling and 20 shillings per pound.

It was a challenge figuring the value of a pocket full of change. And to make it worse, the 1 pence coin was about the largest, a copper coin about the size of a 50 cent piece or silver dollar!

To confuse things further shops sometimes priced goods in guineas, which I believe was an unofficial value of 21 shillings (i.e. 1 more shilling than a pound).:confused2:

They converted to a decimal system in 1971.

 

[LD1]

I dont use charts. I always just calculate it exact X's whatever % efficency you think you can run. For me, remembering 43,560 sq ft per acre is easy.

That is the only # I need to remember.

8' mower x 4 MPH x 5280ft in a mile = 168,960 sq ft per hour

168,960/43,560=3.8 Acres per hour MAX @ 100% efficency.

Allthough I think 4 MPH may be a tad fast for 12-18" tall grass

 

[NativeSon]

This is really good info and gives a better perspective of seat time when mowing.

Charlie

 

[KTurner]

Thanks FWJ. Anyone think 4MPH is a reasonable speed mowing 12-18" tall pasture grass with a 8' finish mower behind my M-7040?

I use a Ford/NH 3230 (32hp 2wd) with a 6' Caroni side discharge RFM to cut ours (just personal, no business). I'll normally mow in 4th gear, which is about 5 mph. Grass can't be too wet or thick or things start clogging and the belts start slipping. Normally it doesn't get real thick, but thicker means it has to be shorter. About 12" or so seems about right. If I wait a little too long, I'll switch to 3rd gear, about 3.5 mph. If I wait more than a little too long, I pull out the rotary cutter and switch back to the RFM next time. It's very flat here and the sections with obstacles are cut with a riding mower.

I've only been using this a couple years and this is the approach I ended up with after some trial and error. Haven't used any other equipment, so I don't know how it would change with a rear discharge RFM or a flail.

Keith

 

[Builder]

I dont use charts. I always just calculate it exact X's whatever % efficency you think you can run. For me, remembering 43,560 sq ft per acre is easy.

That is the only # I need to remember.

8' mower x 4 MPH x 5280ft in a mile = 168,960 sq ft per hour

168,960/43,560=3.8 Acres per hour MAX @ 100% efficency.

Allthough I think 4 MPH may be a tad fast for 12-18" tall grass

I think that's where the problem is. How do you calculate overlap, turn time, breaks to empty bladder, etc. I just needed a rough calculation so I know how long it'll take to get job done. Thanks to all contributors.

 

[jenkinsph]

Builder,
If you are using a 96" mower I suspect you will loose about 10% on overlaps. For turns if you have a regular shape with long passes you will loose another 5%, if it is more irregular in shape you mal loose 10% in turns. without seeing the pasture this is my best guesstimate. I will stick my neck out and say 80 to 85% efficientcy. Pee, take breaks and talk on your cellphone on your own time.

What height do you have in mind to cut this? If it is tall enough I would try the bushhog first as there is a big difference between cutting 5' tall stuff and 18" stuff. Your MX8 may do a good job for you as 18" grass is easier for the hog to handle than it is for the finish mower.

Using the first formula in the thread (width of cut in inches x ground speed) /100 was very accurate(98 to 99%) compared to working it out the long way.

 

[tornadowatchranch]

builder

I haven't ever had one but it seems as if the woods 990 might be a good match for your needs. It is a finish mower but has free swinging blades like a hog. They are pricey though

Woods Equipment Company - RM990 series 90?

good luck

the wind

 

[Builder]

That is a great mower, but it won't handle my M7040's power output. The 990 is maxed-out at 50HP. I'm 70 engine and 61 PTO.
I'm gonna try either my MX-8 with really sharpened blades or I have access to a 15' finish batwing.

 

[TripleR]

We couldn't do 4 mph on our 8' Caroni in tall grass without smoking belts or getting poor quality cut. It has the swinging blades like the Woods and have been a very tough mower. We pulled it with a 72 and 80 hp tractor.

 

[Builder]

TripleR, How is the quality of cut with that mower?

 

[Farmwithjunk]

That is a great mower, but it won't handle my M7040's power output. The 990 is maxed-out at 50HP. I'm 70 engine and 61 PTO.
I'm gonna try either my MX-8 with really sharpened blades or I have access to a 15' finish batwing.

SOME bush hog style cutters do really well as a "lawn mower" once the blades are sharpened a bit. Some don't.... More often than not, they'll "winrow" clippings more than a finish mower would typically. If there's an option for "high lift" blades, they make a big difference.

One "brush mower" I've seen cutting grass toa nice finish, and was particularly impressed with is the Bush Hog brand model 3008. 8'-2" width, dual spindle, so it's not nearly as long as a dual spindle 8'er. They ride nice and stable, even at moderate speeds. That helps the consistency of cut height. It seemed to spread clippings quite well. It was being used to groom pastures at a horse farm near Lexington Ky. The place looked like a golf course!