Spec,
To add to John's comments, the fill and release is usually a gentle manouevre particularly with a belly tank. For example, . You might go from an empty hover power setting of say 45% to a full power setting of say 95% to leave you a bit of margin to get off the water. In other words, when you fill over the 40 seconds, you are applying say 50% of your torque progressively over the 40 seconds as you get heavier. During a lift off from the ground to the hover, you might apply 50% torque in just a few seconds to get airborne.
You can be accidently rough with the bucket filling though. (Of course I never have
) If you pull up too quickly, you can snatch the load by jerking it from a slack line to taught. This "shock loading" can be quite rough, but is not as severe as doing the same thing during a normal load. That is because a normal load is either weight on or off the hook, but the water supports the bucket as it is pulled out, and can bob up and down in a bit thereby lessening the shock loading.
Releasing takes a finite time from both bucket and bellty tank and causes little abrupt change. If you accidently punch the whole bucket off rather than release the water (of course I never have
) then you do get quite a jerk.