Found this,,,,the link gives a table for ground effect percentages,,,and effort required,,,,,


Calculating Winch Loads

Total Weight = Vehicle Weight + Load weight

Winch Pull = ( <Slope degrees> * Total Weight /60)

Ground Factor Weight = Winch Pull * Ground Effect Percentage

Winch Load = Winch Pull + Ground Factor Weight

Example. Given:

* Vehicle weight = 4,400 pounds
* 300 pounds of total load weight
* winch up a 50 degree slope consisting of shallow mud

Total Weight - 4400 + 300 = 4700

Winch Pull - (50*4700/60) = 3917

Ground Factor Weight - 4,700 * 35% = 1645

Winch Load - 3917 + 1645 = 5562

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