UKH

Eldrid ohm has a minimum weight for the belayer of 40kg. I can't work out why this would be. My son is 38 kgs and I'm 65 kgs. What difference would the extra 2kgs make ? I'm well within the envelope of acceptable weights for the lead climber (if my son were 2 kgs heavier). 

Can't for the life of me workout why there is a minimum weight. 

They have to put a limit somewhere, it wouldn't be suitable with a 10kg belayer. 

I don't imagine it's mandatory, just what they've tested. How practiced and alert your son is at belaying will be more important than those two kg.

My daughter weighs about 25kg and seems to get on ok with the ohm, though I do make sure she's anchored to a tree to prevent her being pulled around if I were to fall.

Potentially not heavy enough to ensure the rope is tugged into the groove before they fly up I guess?

2kg is pretty marginal, though.  And if anchored they are in effect infinitely heavy.

Just in case anybody chances upon this discussion in the future the ohm worked fine in practice. I'm 65kgs and my son is 38kgs. He was able to lower me safely and to take a fall comfortably. I would not hesitate to use it again. 

My nephew belayed me when I was 92kg and he was 50. He was able to lower me easily. The weight difference is the important bit...