Actually, in timing it, I don't think there is much difference between hydro planes and blowing balasts while keeping shaft RPM at 100.
So, realism aside, it's about 15 minutes to come up and shoot.
I know that I will never meet the high standards of the GRP (GWX Realism Police). Not even if I get a waterproof laptop and play in the shower with subwoofers shaking the bathroom!
* Above said in the spirit of jest ... no real insults implied or intended.