Drilling a hole in shaft after new prop install

[Stefanojo]

So I got myself a new Campbell Sailor prop (love it).  The diver I hired to install it has been trying to drill a hole through the shaft in order to put a pin through it to secure the second nut. He told me this is SOP. The problem is is he hasn't been able to drill a hole through the shaft. He's broken multiple bits and supposedly has the correct gear. He's been in consultation with our local prop shop. It just seems odd. He thinks the shaft is made out of something other than stainless. I have no idea. Figured I'd check in with the brain trust

[waughoo]

Stainless can be pretty problematic to drill.  I can only imaging the added challenges of doing it under water.