Acres per hour to bush hog?

[scott_vt]

Over the years I have studied and done all the calculations and the only certainty is that it always took longer than I figured.

Good Evenin Sixdogs,
Yeah and especially when the wife waves to you from the front porch, and its time for lunch !

 

[sixdogs]

Good Evenin Sixdogs,
Yeah and especially when the wife waves to you from the front porch, and its time for lunch !

In Maine we used to try to bale and store a lot of hay a day (1200-1500) and with a high-capacity baler and thrower and wagons and two-speed hi-lo transmissions, it's hard to get started and stopped. My time and distance calculations were precise and not a moment could be wasted. Even less depending on the weather because of the chain of events like wagons and hay crew and such.

My dear wife would often drive the half-mile through the field from the house (I could see her coming) and then, rather than use sign language over the roar of everything, motioned she couldn't hear. OK. By the time I lurched forward to clear the bale chamber, the thrower stopped spinning and the flywheel on the baler stopped turning, in was maybe five minutes before you could hear.
Then she would ask something like "Are you thirsty?" Of course not, it's 90 degrees, I'm under severe time pressure to keep the pace up and I've been out here for five hours. "Why would you think that"?

So, budding mathematicians, forget what the book says. I use the lumber method that says add 15% for waste. While at it also add 15% for the law of unintended consequence. That was a number I could hit.

 

[thatguy]

With my 2005 Kubota B7510HST (21 hp engine, 17 hp pto) and a 4-ft King Kutter medium duty hog, I could cut about 0.5 acre/hr in 3-4 ft tall pasture and about 1 acre/hr in 1-2 ft tall stuff. Every few hours I'd have to stop and clean the trash off the screen in front of the radiator.

I would agree with this and my 2320 is very similar in HP...

Last spring I waited until the fields were in that 4' range before I mowed them the first time and it took for e-v-e-r.. I could go a tad faster than I was (which was almost a crawl it seemed), but i would leave a lot of uncut stuff..

Later on I would mow them when they got in that 2' range and I could go much faster..

Brian

 

[Farmwithjunk]

Interesting, the excel sheet I made a while back says 1.69 acres/hour for a 4' cutter. It's nice to get confirmation from an expert!

jb

I snatched that fast and simple formula from "PRARIE FARMER" magazine back in the '70's. They even have more to the formula. You can reverse the steps to calculate inefficiency. the "100" is based on 100% efficiency. If the reversed formula (based on acreage actually worked in one hour) turns out as let's say, 85, you're 85% efficient, or 15% inefficiency. When calculating tillage work, that can also include things like wheel spin. Most commonly, it includes time lost making turns, reduced working width because of over-lap, and time spent taking breaks.

I've used this formula to estimate large acreage mowing in my business. It's EXTREMELY accurate, not to mention simple and quick.

 

[LoneCowboy]

All due respect to farmwithjunk who knows mowing, there is NO WAY you get 1.5 acres per hour with a 4' cutter
You'll be hard pressed to get 1 acre per hour.
I'd figure on 3/4 of an acre per hour.

5280 feet in a mile, figure 3mph (fair guess with a 19hp scut), that's 15840 feet covered in an hour

figure 3 feet of coverage (you lose 2" on the outside minimum either side and really you have to overcut more than that, we'll do the calculation with 3.5 feet in a minute)
that's 47520 square feet covered in an hour, just over an acre (44,000 m/l)

at 3.5 feet 55440 square feet covered

WITHOUT TURNING
that's one 3 mile long row, total efficiency, no bumps, no turns nothing.

.75 to 1 acre an hour in real world.

 

[Redneck in training]

All due respect to farmwithjunk who knows mowing, there is NO WAY you get 1.5 acres per hour with a 4' cutter
You'll be hard pressed to get 1 acre per hour.
I'd figure on 3/4 of an acre per hour.

5280 feet in a mile, figure 3mph (fair guess with a 19hp scut), that's 15840 feet covered in an hour

figure 3 feet of coverage (you lose 2" on the outside minimum either side and really you have to overcut more than that, we'll do the calculation with 3.5 feet in a minute)
that's 47520 square feet covered in an hour, just over an acre (44,000 m/l)

at 3.5 feet 55440 square feet covered

WITHOUT TURNING
that's one 3 mile long row, total efficiency, no bumps, no turns nothing.

.75 to 1 acre an hour in real world.

My wife is an expert with Grasshopper mower. It has 25 HP, 6ft deck, turns on a dime and is significantly faster than any tractor with a bush hog. She is able to mow about 8 acres of hilly pasture with trees in about 8 hours.
What I am saying is that the time lost turning and going around obstacles is usually way underestimated. Especially for tractors. We have both mower and tractor with bush hog so I can compare.

 

[greenmule]

This time next year,he'll know.

Another thing,an acre is a big piece of ground,its about 70 yards by 70 yards.

 

[flusher]

With my 2005 Kubota B7510HST (21 hp engine, 17 hp pto) and a 4-ft King Kutter medium duty hog, I could cut about 0.5 acre/hr in 3-4 ft tall pasture and about 1 acre/hr in 1-2 ft tall stuff. Every few hours I'd have to stop and clean the trash off the screen in front of the radiator.

A little clarification: in tall weeds with only 20hp and a 4-ft mower, I found it difficult to make full-width cuts without lugging the engine severely. I had to make about 2 to 3 ft wide cuts in order to get decent ground speed in that situation.

 

[Farmwithjunk]

All due respect to farmwithjunk who knows mowing, there is NO WAY you get 1.5 acres per hour with a 4' cutter
You'll be hard pressed to get 1 acre per hour.
I'd figure on 3/4 of an acre per hour.

5280 feet in a mile, figure 3mph (fair guess with a 19hp scut), that's 15840 feet covered in an hour

figure 3 feet of coverage (you lose 2" on the outside minimum either side and really you have to overcut more than that, we'll do the calculation with 3.5 feet in a minute)
that's 47520 square feet covered in an hour, just over an acre (44,000 m/l)

at 3.5 feet 55440 square feet covered

WITHOUT TURNING
that's one 3 mile long row, total efficiency, no bumps, no turns nothing.

.75 to 1 acre an hour in real world.

Well, I hate to shoot holes in your theory, but I'm gonna. My son-in-law has a Kubota 7510 (???) and a 4' KK mower he uses to mow a 7-1/2 acre piece of ground behind his house. He ROUTINELY averages better than 1.5 acres per hour.

Go back and look at my estimate and formula. I used 4mph as average speed, NOT 3mph as you used. Using my formula and YOUR speed (of 3mph,) it still equates to 1.2 acres per hour. It's conceivable that condition would require even slower speeds, or , conditions may allow HIGHER speeds. My answer was based on conditions, shape of field, and operator ability allowing a moderate speed and not a lot of wasted motion. Read CAREFULLY my original reply and it states details on estimating efficiency/lost efficiency, as well as how to estimate rate of cut at VARIOUS speeds.

And, I'll take BTDT over theory any day of the week. I've seen a 4' cutter mow more than 1-1/2 acres per hour enough to know it's more than just a possibility.

 

[kebo]

Interesting, the excel sheet I made a while back says 1.69 acres/hour for a 4' cutter. It's nice to get confirmation from an expert!

jb

That's pretty close there. For several years I bush hogged just over 2 acres for a neighbor (where my parents live) with a JD 750 (21hp) and 4ft Landpride bush hog and it usually took about 1 and 15 minutes. Sold that set up and now have the JD 790 with a 5ft hog, I expect it take right at 1 hour this year once the green up starts, which is not very far off here in SC.