Horse Power Questions

[58RudeBigTwin]

Forgive me if this question has already been brought up, but I've never understood horse power ratings. Here's what I don't understand...

I have a 35 HP outboard, and I also have a 45 HP John Deere Tractor, but I don't expect my outboard would pull a 2 bottom plow. My understanding is that horse power is basically the speed at which an engine will do work (work/time) and torque is the amount of work (force*distance) an engine will do. So is the only reason the tractor will pull a plow and the outboard won't is the torque output of the engine or in theory with the proper transmission could you get an outboard to pull a plow?

Anyway it is raining today so I'm not out fishing and my daughter is monopolizing the TV!

 

[JimS123]

Re: Horse Power Questions

Forgive me if this question has already been brought up, but I've never understood horse power ratings. Here's what I don't understand...

I have a 35 HP outboard, and I also have a 45 HP John Deere Tractor, but I don't expect my outboard would pull a 2 bottom plow. My understanding is that horse power is basically the speed at which an engine will do work (work/time) and torque is the amount of work (force*distance) an engine will do. So is the only reason the tractor will pull a plow and the outboard won't is the torque output of the engine or in theory with the proper transmission could you get an outboard to pull a plow?

Anyway it is raining today so I'm not out fishing and my daughter is monopolizing the TV!

I think you are confusing apples and oranges. "Horsepower" is defined as a unit for measuring power. Specifically, 1 HP is equal to a rate of 33,000 foot-pounds of work per minute.

Your OB motor won't pull a plow because the propeller would get stuck in the mud. And your tractor / plow won't push a boat because it has wheels and no propeller.

HP is HP. Either your boat motor or plow would satisfy the opposite task if it were properly geared and set up accordingly.

 

[bassman284]

Re: Horse Power Questions

Like Jim says. Your 35 could pull a semi trailer if it was geared for it. Not sure how long but it could be done.

 

[5150abf]

Re: Horse Power Questions

I would imagine the tractor engine makes a boat load more torque than the outboard too, you can have engines with equal HP but have torque numbers be vastly different but I do agree with proper gearing any engine could do almost any job.

 

[mudslinging79]

Re: Horse Power Questions

look at semi trucks and dragsters, both have gobs of torque, but you dont see a dragster hauling trailers, its in the gearing. your outboard could feasably plow the bottom of the river if you could gear it low enough. be a pain keeping the fish out of your crops....

 

[seahorse5]

Re: Horse Power Questions

Horsepower is only a mathmatical formula. It is simply the engine's measured torque in ft.-lbs. at a certain rpm multiplied together and divided by 5252.

an engine turning 20,000 rpm can have the same "hp rating" as an outboard running at 3500 rpm.