Some divers will do it. The diver who changes our zincs also keeps spare max-prop parts (the special screws and cotter pins, etc). He has re-pitched our 3 blade classic
in the water
without a problem. And, we are in cold PNW waters, and he does it while wearing gloves.
When looking for a diver for this, be sure and find someone you know has done it before (personal references
, etc.). Don't just pick a diver who says "Sure, I can do it. Can't be that hard" ;-)