The charge varies with helicopter size and ambient conditions. When there is lots of dust in the air, rain or high humidity the chances of being shocked are much higher due to the increased friction. But operating with a mid sized helicopter like a S76 the average shock rarely exceeds something you may get off a car door. Being paranoid about the shock off a wire is not smart if you are in the water awaiting rescue as you may only get one chance to grab the strop in bad weather, and waiting for it to be earthed nicely alongside you may take a while.
The technique of ‘stomping’ the hook into the ground with your foot will certainly remove a charge, but is not the best practice for a very thin piece of live saving wire that is about to haul you to safety.
Watching three crew members in a submarine conning tower back away from my out stretched hand one day would have been amusing had I not known how hard the boys were working to get me onboard in the reasonable swell and fading light. After about the fourth swing past and one smash into the side of the conning tower, I pulled a shot-bag from my leg pocket that was connected to 15’ of H.I. line. I hurled this at the occupants and when it bounced off one of their heads and into the tower I yelled, “its Fu@ki@g well earthed now!” The bloke we were going to get was then recovered with just a few more heartbeats depleted.