What is the maximum force one person can apply to a hand crank winch as a percentage of body weight.?

Question

I remember reading that a person can apply around 75% of body weight to pulling a rope.

What I'm looking at is hypothetical output on a 12:1 yacht winch adapted for tree work (Called a GRCS).

My searches result in hits selling electric winches.

>>You weigh W = 200 pounds (after Christmas >>dinner) and can lean on the crank with about half >>your weight. Thus, effective weight is = W X .5 = >>100 pounds.

This is the direction I'm going, is .5 a hard rule of thumb, or is that SWAG.

I guess I should say I'm looking for a rule as to the value of efficiency (W * E)= winch input.

Answer 1

Frankly I don't think your question is at all arbitrary. You have a 12:1 winch and want to know how much force you can generate when leaning on it with all your weight. The answer is straightforward: 12 X your effective weight. Your effective weight = W X efficiency; where W is your measured weight and efficiency is the percentage of that W you can bring to bear on the winch handle.

EXAMPLE: You weigh W = 200 pounds (after Christmas dinner) and can lean on the crank with about half your weight. Thus, effective weight is = W X .5 = 100 pounds. Therefore, the force on the working end of the winch is 12 X 100 pounds = 1,200 pounds. Now understand, you don't get nothin' for nothin'. So you'll need to do a lot of cranking to get the working end (attached to that tree) to move just a small distance.

If you want to work out how much of your weight you can put onto the crank, try putting a bathroom scale on the floor and then leaning over to push down on it. Whatever you can get the scale to read would be about your effective weight.

NOTE: The number I gave above are just examples. To do this right, you need to know what your own effective weight will be when leaning on that crank. There is no rule of thumb that I know of. However, if you do the bathroom scale experiment and place the scale at the same distance, height, reach, etc. of the crank on your winch, you should be able to measure your effective weight.

Answer 2

That is an arbitrary question, you really need to define your question more, with a long enough lever you can move a mountain.