> I've seen 12V boat winches for sale locally at NZ$99 and would
> like to know what HP the motors actually are,

> 1.8m (6ft) / minute
> 900kg capacity, pulling with load (presumably this means dragging ?)

> How would I work backwards to get the HP of the motor?

I'll assume the 900 kg is dead load capacity - that may not be what 
they mean. If not it'll be lower and following figures will be reduced 
accordingly.

Work = force x distance.
Power = work/time

Force in Newton = kg x g

Work = 1.8m x 900 kg x 9.8 (=g) =~~  16,000 Nm (or Watt-seconds)

Power = 16,000/60s = 267 Watt

About 1/3 HP.

Expected current drain at 12 V would be > 267/12 = 22 amps at above
load. Probably 25 - 30 amps, maybe more.



        R "E&OE" M



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