We keep chickens, ducks and geese and wet pluck them all by hand. They are dunked into water that is @ 65-70 C (we estimate rather than thermometer check) until we can pull out the wing feathers with no problem. For the ducks and geese we add a dash of washing up liquid. Tried dry plucking but could not get on with it and it seemed to take forever so the birds got dunked!!
I have read somewhere in the past that hanging a duck/goose for 5/7 days before plucking and butchering makes it easy to pluck and improves it flavour, not sure is that is true or not as I have never tried it.